The best diet for optimal blood sugar control & health
Author: kaitiscotland
I am a Scottish doctor who is working to improve the outcomes for people who have diabetes using a low carb diet, and advanced insulin techniques when necessary. Professionally I provide expert witness reports in the clinical forensic and family medicine areas and I also provide complementary therapies. I enjoy cooking, cinema, reading, travel and cats.
BMJ 20 May 2023 Adapted from Effectiveness of spironolactone for women with acne vulgaris in England and Wales by Santer M et al.
Women over the age of 18 living in England and Wales whose acne was bad enough to merit antibiotic treatment, were randomised to use either Spironolactone or placebo. They were allowed to continue the topical treatments that they were already using for their acne. Their scores on their acne specific quality of life were assessed by themselves and a clinical assessor evaluated their acne.
200 women were recruited to each group. The findings showed a small but statistically significant improvement after 24 weeks of spironolactone use at 100mg a day. Their average age was 29 years.
One fifth of those taking Spironolactone reported headaches.
The assessors thought that 19% of the women had noticeable skin improvement compared to 6% of the placebo group. The women themselves reported a quality of life improvement of 17 points in the placebo group and 21 in the Spironolactone group.
The authors think that this improvement is good enough to be a useful alternative to long term antibiotics.
My comment: Having suffered from acne since the age of 11 I am pleased to see another treatment being offered for this condition. Almost all teenagers of both genders get acne. In boys it tends to be more severe than in girls but it tends to resolve completely. For some women it never resolves and they have it persistently throughout their lives. If a woman still has it by the age of 24 the acne is likely the persistent type. Acne, even with the best treatment is very slow to respond, and at best will improve at 10% a month. This is for Roaccutane. I wonder what the effects would be over a longer length of time for the other women in the study. The results, though promising are not stunning, and diligent use of topical treatments and consideration of using anti-biotics and Roaccutane will also need to be considered to resolve symptoms.
Spironolactone is a diuretic that can be also used to control facial hair growth in women. It is sometimes used if someone has high blood pressure that does not respond to other drugs.
3 tablespoons butter, divided 1 garlic clove, minced 1 cup chopped onion 1 cup chopped celery 1/2 cup chopped carrot 1/2 cup diced red bell pepper 2 cups seafood stock or clam juice 1 teaspoon seafood (Old Bay) seasoning 1 tablespoon fresh thyme leaves 1/4 teaspoon freshly ground black pepper 1/2 teaspoon salt 1/2 teaspoon crushed red pepper flakes (chili) 1 cup cherry or grape tomatoes, halved 1 lb firm boneless fish fillets (such as halibut, cod, red snapper, sea bass, grouper), cut into small cubes 8 oz medium shrimp, shelled, deveined, tails removed and cut in half 8 oz sea scallops, halved 1 cup heavy cream 1/4 cup minced fresh parsley, plus extra for garnish
Directions
In a large saucepan over medium heat, melt 2 tablespoons of butter. Add the onion, celery, carrot and bell pepper. Cook until the vegetables are tender, 3-4 minutes. Add the garlic and stir into the vegetables. Pour in the chicken broth and bring to a simmer. Cover the pan and cook the vegetables until tender. Remove the cover and the salt, pepper, chili flakes, seafood seasoning, thyme, and tomatoes. Sir well.
Add the fish cubes, Cook stirring the mixture gently for 2 minutes. Add the shrimp and scallops and cook for 2 minutes more or until the seafood is cooked. Add the cream, parsley, and remaining tablespoon butter, heating gently until the butter is incorporated. Garnish with chopped parsley. Serve in bowls immediately. A salad is a good accompaniment.
2 hothouse cucumbers, halved and seeded, but not peeled 3 red bell peppers, cored and seeded 8 plum tomatoes 2 red onions 6 garlic cloves, minced 46 ounces tomato juice (6 cups) 1/2 cup white wine vinegar 1/2 cup extra virgin olive oil 1 tablespoon kosher salt or to taste 1 1/2 teaspoons freshly ground black pepper
Roughly chop the cucumbers, bell peppers, tomatoes, and red onions into 1-inch cubes. Put each vegetable separately into a food processor fitted with a steel blade and pulse until it is coarsely chopped. Do not overprocess!
After each vegetable is processed, combine them in a large bowl and add the garlic, tomato juice, vinegar, olive oil, salt, and pepper. Mix well and chill before serving. The longer gazpacho sits, the more the flavors develop.
Adapted from a pie recipe kindly offered by Commememuchos.
Up to 25 grammes of wheat or wheat free flour
900g of veal or beef cut into inch squares
25 grammes of butter (about an ounce for the oldies like me)
1 tablespoon olive oil or coconut oil
2 large onions thinly sliced
2 large carrots cut in 1 to 1.5 cm slices
2 teaspoons of Worcester sauce or sherry vinegar or red wine
2 teaspoons tomato puree
500mls Guinness or other strong dark beer
300mls meat stock ( or use stock cubes. The Italian make Star do particularly good ones available from Amazon for about double the price from getting them in Italy. Thanks Alexandra for the tip!)
2 teaspoons sugar
2 tablespoons water
salt and pepper to taste
Method
You will need a large stove top casserole dish eg Le Creuset or similar. A sturdy large saucepan will do.
In a large bowl put in the flour and salt and pepper. Mix.
Coat the meat cubes in this.
In your casserole dish or large saucepan heat the butter and oil over a low heat till the butter has melted and then turn up the heat and sear the meat in batches. Once done set aside. This stage always takes rather a long time. It is good to listen to podcasts or music doing this.
Now fry the onion and carrots gently for about two minutes.
Add back the meat to the casserole dish and season with Worcester sauce, tomato puree, Guinness, hot meat broth and sugar. Add black pepper and salt. Bring to a boil.
Now cover the casserole and turn down the heat to a simmer for about 2 hours.
Casseroles are always tastier the next day but can be eaten immediately.
Adapted from BMJ 20 May 2023 Risk of diabetes with statins by Ishak A Mansi et al.
Statin medications lower cholesterol and have an anti-inflammatory effect that shows benefits in cardiovascular morbidity and mortality, particularly for secondary prevention, when a heart attack or stroke has already occurred. Yet studies have shown a 46% relative risk increase for diabetes, possibly due to a direct toxic effect on mitochondrial pancreatic beta cells.
Based on some randomised controlled trials it is thought that for every 100 to 250 people who take statins for 2 to 5 years, on additional person will develop diabetes due to taking the statin. Studies also indicate that the risk is higher if the statin dose is higher. The risk is greatest in the first four months of treatment. People who already have diabetes may find that their blood sugar control worsens. If you already have impaired fasting blood glucose, metabolic syndrome, fatty liver, are over 65 in age, or have obesity, this can tip you into a diabetes diagnosis.
It is still thought that despite these problems, statin use is still more beneficial overall compared to not prescribing them, particularly for if you have already had a stroke or heart attack.
What can you do?
Exercise and adopt a low glycaemic diet. This will also reduce your cardiovascular risk independent of its beneficial effect on improving insulin resistance and lowering blood sugars.
What can your doctor do?
Consider prescribing Metformin or a glitazone if you are starting a statin and already have pre-diabetes.
Check blood glucose levels before starting a statin and at three months afterwards and then yearly.
Check Thyroid function as low thyroid levels can raise cholesterol levels.
Think twice about high intensity statins. Are they really necessary?
Change medications that already raise the risk of diabetes such as thiazide diuretics and beta blockers, particularly if there are no strong indications for these particular drugs.
Minimise drug interactions from other medications that raise the effects of statins in the body. These include: amiodarone, clarithromycin, diltiazem, grapefruit juice, itraconazole, ketoconazole, protease inhibitors as these increase the potency of simvastatin, atorvastatin and lovastatin.
Cyclosporin affects transport proteins and also raises the potency of statins.
My comment: I usually pan fry salmon or put it in tin foil with some butter and white wine and cook it in the oven for 15 minutes. This recipe from the New York Times by Ali Slagle invites us to slather the fish in copious amounts of olive oil, lemon rind and juice and add whatever flavourings we fancy and to cook it in the oven. Having eaten a large amount of salmon cooked in various ways over the years. I can say that I was very impressed and will probably keep to Ali’s method from now on. It does produce a silky succulent salmon that is difficult to beat.I added rosemary to the fish.
For four servings:
1/4 cup extra virgin olive oil
4 x 6 oz salmon fillets or one 1/2 pound salmon fillet
these can have the skin on or be skinless and patted dry
salt and pepper
2 lemons
Suggested flavourings:
rosemary, thyme or oregano
garlic
fresh or dried chili
olives
anchovies
bay leaves
crushed fennel or coriander seeds
Method
Heat the oven to 350 degrees (180 degrees C)
Drizzle olive oil in the base of an oven proof dish that will fit the salmon
put the salmon skin side down
season with salt and pepper
Then peel thick strips of zest from one lemon and add to the baking dish
Juice the lemon and squeeze it over the salmon
Add any additional flavourings
Bake for 13 to 20 minutes depending on the thickness of the salmon and baste half way through
Transfer to a warm serving plate to rest for 5 minutes. Take off the skin if it is still on.
Remove the lemon peels.
Squeeze the juice of the other lemon into the olive oil sauce mixture
Adapted from: Ultra processed foods and binge eating: a retrospective observational study by Agnes Ayton MD et al. Nutrition 84 (2021) 111023 and Treating binge eating and food addiction symptoms with low-carbohydrate Ketogenic diets: a case series by Matthew Carmen et al. Journal of Eating Disorders (2020) 8:2.
In general ultra processed foods are high in sugars and fats and low in natural protein. They are considered to be not modified foods but formulations made mostly from substances derived from foods, many of them not normally used in culinary preparations, as well as additives. A series of processes are used to create the final product. Many ingredients including sugars are metabolically active and may have an addictive potential. Such foods include soft drinks, sweet or savoury packaged snacks, reconstituted meat products, pre-prepared frozen dishes and diet products.
Ultra processed foods have been gradually displacing unprocessed or minimally processed foods and freshly prepared meals. In the UK the percentage of foods eaten in this category ranges from 30-80% and the average is 56.8%. This has led to an increase in the amount of starches, sugars and fats, and a decrease in the amount of protein consumed. Increases in the amount of these foods consumed is linked to increasing rates of obesity and metabolic disorders. They seem to reduce satiety and stimulate overeating. People who are allowed to eat what they want end up eating more carbohydrate and fat but not protein. This results in widespread endocrine changes. Animal and human experiments show that ultra processed foods interact with various hormonal and neurobiological systems that affect food intake.
Responses to common foods vary from person to person and are influenced by such factors as insulin resistance, sleep, stress, exercise and the microbiome. These differences affect glucose tolerance and insulin sensitivity.
The detailed records of 73 people who had attended an eating disorders clinic in Oxford between 2017 and 2019 were examined retrospectively. Only 3 were men, the majority of patients being women.
Eating patterns showed that while breakfast and snacks were commonly missed, most people ate lunch and dinner, and binge eating tended to occur more towards the evening. During the day most people chose foods low in fat and protein.
The foods consumed during binge eating were 100% ultra-processed such as chocolate, ice cream, crisps, sandwiches, biscuits, cakes, pizza, smoothies and doughnuts.
Meals were often missed during the day indicating that dietary restriction is shared between people with eating disorders regardless of the actual precise type.
A separate cross over study reported that patients did not notice a difference in palatability between normal and ultra processed foods, yet ate 500 k cals more a day on the ultra processed foods. The hunger hormone ghrelin, fasting glucose and insulin are all raised with ultra processed foods and the appetite suppressing hormone peptide tyrosine is reduced. Although fat and carbohydrate were increased in amount, protein intake remained the same suggesting that excess intake is driven by dilution of dietary protein.
Anorexia Nervosa is associated with increased insulin sensitivity while Bulimia Nervosa and Binge Eating Disorder are associated with insulin resistance. Indeed 30% of patients with BED had impaired glucose tolerance. It is possible that metabolic factors contribute to binge eating.
Overconsumption of food may also be driven by combinations of sugar and fat not found in nature and also non-nutritive sweeteners.
The nutrient sensing system plays a critical role in regulating striatal dopamine and reward. This is subconscious. The second conscious system influences food choices based on beliefs of healthfulness, cost and so on, which are heavily targeted by advertising and the food environment.
Patients with eating disorders choose diet products, which are actually often ultra processed, having the belief that these are healthier options, unaware of the metabolic and neurobiological effects that impair accurate sensing of nutrient content by the brain and result in uncontrollable eating during a binge episode.
The cavalry coming over the hill in all this could be the good old ketogenic diet.
Carmen et al from Stanford University reported on three patients aged 34, 54 and 63 whose average BMI was 43.5. They undertook a ketogenic diet consisting of 10% carbohydrate, 30% protein and 60% fat for 6 to 7 months. They all had binge eating and food addiction symptoms.
They were all pleased to report no major adverse effects on the diet and a significant reduction in binge eating episodes and food addiction symptoms such as cravings and lack of control. They also lost between 10 -24% of their body weight.
After the study finished, they all continued on the diet for 9-17 months and continued to have no recurrence of their original binge eating and cravings. In one patient with a pervasive low mood this also substantially improved.
Food addiction symptoms have been described as an addictive response to foods such as sweets and starches. These include much time spent obtaining food, feelings of withdrawal when off food, continued use despite adverse consequences, important activities reduced or given up, repeated unsuccessful attempts to stop, and eating more than intended.
Rates for food addiction are up to 42% for patients who are waiting on bariatric surgery. In people who have obesity the rates are 15 to 20%.
The ketogenic diet produces appetite suppression, lower hunger, greater satiety, greater fat burning, lower fat formation, more glucose being made in the liver and the increased thermic effect of proteins.
The patients were asked to keep to 20-30g of carbohydrate a day or less and to eat whole foods, not processed, including meat, seafood, nuts and eggs, 4 oz of hard cheese a day, 2 cups of assorted salad vegetables, cup of non starchy vegetables and low carb fruit. They were asked to not count calories and to eat till they felt full and then stop.
This small case series supports the feasibility of using a low carb ketogenic diet for patients presenting with obesity and self reported binge eating and food addiction symptoms.
Ketogenic diets can also be used for paediatric epilepsy, gastro oesophageal reflux, irritable bowel syndrome, and Crohn’s disease. Mental disorders such as bipolar disorder, psychosis and schizophrenia.
The “carnivore diet,” based on animal foods and excluding most or all plant foods, has attracted recent popular attention. However, little is known about the health effects and tolerability of this diet, and concerns for nutrient deficiencies and cardiovascular disease risk have been raised.
We obtained descriptive data on the nutritional practices and health status of a large group of carnivore diet consumers.
A social media survey was conducted 30 March–24 June, 2020 among adults self-identifying as consuming a carnivore diet for ≥6 mo. Survey questions interrogated motivation, dietary intake patterns, symptoms suggestive of nutritional deficiencies or other adverse effects, satisfaction, prior and current health conditions, anthropometrics, and laboratory data.
A total of 2029 respondents (median age: 44 y, 67% male) reported consuming a carnivore diet for 14 mo (IQR: 9–20 mo), motivated primarily by health reasons (93%). Red meat consumption was reported as daily or more often by 85%. Under 10% reported consuming vegetables, fruits, or grains more often than monthly, and 37% denied vitamin supplement use.Prevalence of adverse symptoms was low (<1% to 5.5%). Symptoms included gastrointestinal (3.1%–5.5%), muscular (0.3%–4.0%), and dermatologic (0.1%–1.9%). Participants reported high levels of satisfaction and improvements in overall health (95%), well-being (66%–91%), various medical conditions (48%–98%), and median [IQR] BMI (in kg/m2) (from 27.2 [23.5–31.9] to 24.3 [22.1–27.0]). Among a subset reporting current lipids, LDL-cholesterol was markedly elevated (172 mg/dL), whereas HDL-cholesterol (68 mg/dL) and triglycerides (68 mg/dL) were optimal. Participants with diabetes reported benefits including reductions in median [IQR] BMI (4.3 [1.4–7.2]), glycated hemoglobin (0.4% [0%–1.7%]), and diabetes medication use (84%–100%).
Contrary to common expectations, adults consuming a carnivore diet experienced few adverse effects and instead reported health benefits and high satisfaction. Cardiovascular disease risk factors were variably affected. The generalizability of these findings and the long-term effects of this dietary pattern require further study.
My comment: I have summarised the full articleand have removed most of the tables.You will be able to find the full article online should you wish to examine these in more depth.
Introduction
Dietary variety is near-universally recommended in National Guidelines to satisfy human nutritional needs (1, 2). Consumption of a variety of food groups from both plant and animal food sources has been linked to favorable health outcomes in epidemiologic studies (3) and clinical trials (4–6) and is expected to satisfy the recommended DRIs of macronutrients (i.e., protein, carbohydrates, and fats), micronutrients (i.e., vitamins and minerals), and food components (e.g., dietary fiber).
Nevertheless, restrictive diets have long been promoted for various health and philosophical reasons. One notable eating pattern, a vegan diet, that eliminates animal foods has been promoted for ethical (7), environmental (8), and health (9) benefits—including reduction in BMI, improvement in serum lipids, and cancer prevention (9). However, these reported benefits may be confounded by dietary and nondietary health behaviors, and negative effects have also been reported (10). Vegan diet consumers may not meet DRIs for vitamin B-12, calcium, and protein, and adverse events, such as an increased incidence of bone fractures (11), have been observed.
Recently, popular interest has grown in an opposite eating pattern, a carnivore diet, which aims to eliminate most or all plant-based foods. Numerous social media groups (e.g., https://www.facebook.com/groups/worldcarnivoretribe/) have been formed, with membership of many thousands in the United States and other nations, to promote this diet for health and other benefits. Whereas diets high in animal foods have been commonly discouraged owing to high saturated fats content and low density of essential nutrients and bioactive compounds (e.g., fiber, phytonutrients) (12), little is known about the health status of people habitually following a carnivore eating pattern. According to a common view, long-term consumption of a strictly animal-based diet would be associated with significant nutritional deficiencies (13) and confer negative health effects compared with a plant-based diet (14, 15), including poor gut and gut-microbiota health (16–19), an adverse cardiovascular disease risk pattern (20, 21), and other chronic health complications (22).
What little evidence exists for the sustainability of carnivore diets derives from historic reports on Arctic or nomadic societies, clinical case studies, and accounts on nutrition therapy for diabetes mellitus in the preinsulin era c.1920. Early reports by Arctic researchers and population surveys provide evidence that animal-based diets with little to no plant matter were consumed by traditional populations at high latitude during most of the year (23–25), and were associated with good health and longevity (26, 27). Inspired by their experiences, 2 Arctic explorers participated in a study, partly conducted under strict inpatient observation, of a diet containing only meat (27). After 1 y, they reported good health and displayed no clinical evidence of any vitamin deficiency, although a negative calcium balance was reported (28). Of note, the animal-based diets consumed in this study incorporated both lean and fatty meats, including a variety of organ meats; these were frequently boiled, and sometimes consumed raw, with potential implications for the availability of low-concentration or labile nutrients. Likewise inspired by observations on an indigenous diet in St. Lucia, Dr. John Rollo in 1797 successfully treated 2 patients with diabetes with a diet consisting only of meat and fat. Rollo recommended near-complete elimination of plant foods (29), a prescription that was widely adopted and empirically optimized to prolong the life of people with diabetes in the 19th century. Recognizing the link between carbohydrate intake and glucosuria, some physicians allowed intake of low-carbohydrate vegetables (30), whereas others promoted a strictly meat- and fat-based approach for diabetes management [e.g., Cantani, Primavera (31)]. With the discovery of insulin, these dietary approaches were abandoned in favor of less restrictive mixed diets (32), and modern research on an animal-based diet is sparse.
Although several contemporary treatments of obesity or type 2 diabetes promote high intake of meat and fat (e.g., the Atkins diet) (33), these diets typically include, or reintroduce after short periods, consumption of low-carbohydrate vegetables and low-sugar fruits. Whereas a recent perspective suggests that all essential nutrients can be obtained from a carnivore diet (34), few empirical data are available. Therefore, the aim of this study was to characterize the motivation, dietary behaviors, self-perceived health status, and satisfaction of a large group of adults habitually consuming a carnivore diet, and thereby to provide insights into this poorly characterized dietary approach.
Methods
Design
Using an online survey, we collected self-reported data from respondents who self-identified as following a carnivore diet for a minimum of 6 mo. Our aims were to 1) characterize the diet consumed by parti-cipants, 2) describe perceived health status and changes in health since starting the diet, 3) assess perceived symptoms of nutritional deficiencies or other adverse effects, and 4) evaluate the satisfaction and acceptance of consuming a carnivore diet.
Participants and enrollment
Respondents were recruited from open social media communities Inclusion criteria were age ≥ 18 y and consumption of a carnivore diet for ≥6 mo by self-report. Data collection occurred during the period of the COVID-19 pandemic when most people were in lockdown.
Of an initial 3883 respondents, a total of 2029 (52%) respondents were eligible and willing to participate and provided sufficient information to be included in the study.
Data collection and treatment
Survey instruments
Survey questions were developed in consultation with members of the carnivore diet community and addressed several domains: 1) current intake frequency of main food groups and relevant food items, as well as food preparation and related considerations; 2) chronic medical conditions and medication use, anthropometric and laboratory data, perceived health and well-being, and perceived symptoms of nutritional deficiencies or other adverse effects—including in the present and before starting the diet; 3) diet satisfaction and social support; and 4) sociodemographic data. Multiple-choice questions were used to solicit specific habits, reasons for choosing the diet, medical conditions, and medication intake. Modified Likert scales were used to estimate the frequency of intake of prespecified food categories; satisfaction; and changes in health, well-being, chronic conditions, and symptoms. Highest educational attainment was categorized as primary (primary school or less), secondary (secondary school, including high school), postsecondary [intermediate between secondary and university (e.g., some college and technical training)], or tertiary (completed college, university, graduate school, or equivalent). Participants were asked to specify their income category as lower, middle, or upper. Race and ethnicity were self-reported with multiple-choice and free-text options. Self-reported anthropometric and laboratory data were collected for the following timeframes: Prior: within 1 and 5 y before starting the diet, respectively; Present: within a year of taking the survey and ≥3 mo after starting the carnivore diet. Participants were asked to specify source of anthropometrics as clinician or self-measured, and data were prioritized in that order.
Units of measure
To account for the international background of people within the social media communities, respondents were able to select among unit systems (metric, imperial, international system of units, conventional); data were collected accordingly and converted to metric and conventional units.
Calculated variables
Time on the diet and timing of anthropometric and laboratory data were calculated with reported dates and the survey date. Respondents were designated as having diabetes if they reported using the carnivore diet as a way to manage or reverse diabetes, if they had ever been prescribed any oral or injectable diabetes medications, or if they reported an HbA1c ≥6.5%.
Results
Participants
Most respondents were from the United States, Canada, Europe, or Australia; 67% were male; 83% were white and non-Hispanic; and 64% completed college or the equivalent. Income spanned all classes with 14% reporting low, 66% middle, and 20% high income. Seven women were pregnant and 10 were breastfeeding at median 12 mo [IQR: 9–18 mo] postpartum. The median [IQR] time following a carnivore diet was 14 mo [9–20 mo]; 93% of participants stated health reasons as their motivation for beginning the diet.
Red meat other than pork (e.g., beef, lamb, venison, buffalo, goat) was the most commonly consumed food, followed by eggs and non-milk dairy, whereas pork, poultry, and seafood were less frequently eaten. Weekly or more frequent consumption was reported for organ meat by 42%, and for non-milk dairy by 72%. Less than 10% of respondents consumed starchy vegetables, nonstarchy vegetables, fruits, or grains more often than once monthly, and 37% reported no use of any vitamin supplements. Use of other over-the-counter supplements (e.g., dietary, herbal, digestive enzymes, antioxidants) was denied by 75%. Alcohol was rarely consumed, with 63% reporting frequency of less than once a month or never. More than 50% of participants drank coffee at least daily. In contrast to the typical Western/Standard American diets, few individuals following the carnivore diet reported consuming fast foods.
Frequency of making exceptions from the carnivore diet.
Most participants reported eating 1–3 times daily (differentiation between meals and snacks was not queried), including 16% three times per day, 64% twice per day, and 17% once per day. Generally, more participants reported choosing cuts of meat with high (61%) or moderate (37%) fat content as opposed to lean cuts (2%). Seventy-six percent reported a preference for consuming meat at raw, rare, or medium-rare doneness. Intention to achieve nutritional ketosis was reported by 41%, among whom 41% monitored ketone concentrations; 56% intended to achieve a medium or high amount of salt intake, as commonly recommended in the setting of low-carbohydrate diets that are associated with increased natriuresis (36). Additional dietary data are available in Supplemental Table 3.
Perceived health-related outcomes
Participants reported improvements in chronic medical conditions, general health, and aspects of well-being such as energy, sleep, strength, endurance, mental clarity, memory, and focus (Figure 1). Table 3 lists the prevalence of specific medical conditions and changes in their severity. Although most queried medical conditions improved with the diet, lipid abnormalities were variably affected: 56% of participants reported resolution or improvement, 18% stability, and 27% new occurrence or worsening. Ophthalmologic conditions were improved or unchanged with equal frequency.
Reported changes in health status. Participants were asked to rate their current overall health and well-being on a 3-point scale as better (light gray bars), unchanged (dark gray), or worse (black) compared with the time before starting the carnivore diet. Percentage of respondents is given.
TABLE 3
Self-reported prevalence of and changes in chronic conditions and medication usage1
Table 4 and Supplemental Figure 1 summarize changes in anthropometrics and laboratory studies. Median [IQR] BMI decreased from 27.2 [23.5–31.9] to 24.3 [22.1–27.0]. As observed with other diets low in carbohydrate, TC and LDL-cholesterol were markedly elevated, whereas HDL-cholesterol and TG were in an optimal range. The Present ratio of TG to HDL-cholesterol was 1.0 [IQR: 0.7–1.5]. CRP and GGT decreased, and other liver enzymes, Cr, and HbA1c were unchanged from pre-diet to current. Coronary artery calcium score was low at Prior (2; IQR: 0–132) and Present (0; IQR: 0–27) among the few respondents reporting this value.
TABLE 4
Self-reported current and prediet anthropometrics and laboratory studies1
Among the 262 respondents with type 1 diabetes mellitus or type 2 diabetes mellitus (T2DM), prior BMI, HbA1c, and TG were higher than among those without diabetes.Respondents with diabetes experienced relatively large median [IQR] reductions in BMI (4.3 [1.4–7.2]) and HbA1c (−0.4% [0% to 1.7%]) (Supplemental Table 4). Diabetes medication use was significantly reduced. All respondents with diabetes discontinued noninsulin injection agents, 84% discontinued oral medications, and 92% of participants with T2DM discontinued insulin (Table 3).
Reported prevalence of adverse effects or symptoms consistent with nutritional deficiency was generally low, as shown in Supplemental Table 1, and commonly preceded the diet. New or worsened diarrhea occurred in 5.5%, constipation in 3.1%, weight gain in 2.3%, muscle cramps in 4.0%, hair loss or thinning in 1.9%, insomnia in 1.7%, dry skin in 1.4%, itchiness in 1.1%, heart rate changes in 1.1%, brittle fingernails in 1.0%, and menstrual irregularity in 1.0%. Worsening or incidence of any of the other assessed symptoms occurred in <1% of participants. Prevalence and incidence of symptoms were not increased compared with the overall group in participants who denied intake of vitamin supplements or denied consuming organ meat or dairy.
Satisfaction and support
Participants reported high levels of overall satisfaction with the diet (Supplemental Table 5). The majority perceived no impact on their social life, and neutral or positive supportiveness from social contacts. Medical providers were perceived as neutral, supportive, and unsupportive by generally similar proportions.
Discussion
In this social media–based survey, a self-selected group of adults consuming a carnivore diet for ≥6 mo reported perceived good health status, perceived absence of symptoms of nutritional deficiencies, and high satisfaction with this eating pattern. To our knowledge, this is the first modern report on a large group of people habitually consuming few plant foods, a dietary pattern broadly considered incompatible with good health.
Weight loss and other health benefits were most frequently indicated as the motivation for adoption of a carnivore diet. In accordance with this possibility, respondents reported substantial BMI reduction and improvements in physical and mental well-being, overall health, and numerous chronic medical conditions.Respondents with diabetes reported special benefit, including greater weight loss than the overall group, and marked reductions in diabetes medication usage and HbA1c—notable findings in view of the generally low success of lifestyle interventions for obesity and diabetes (37, 38). Although we did not formally assess macronutrient intake, carbohydrate content in meat and other animal-based foods is minimal, and inherent limits to protein intake exist. Both ancestral data (39) and self-reported preference of fatty cuts of meat in our survey suggest high fat intake with the carnivore diet. As such, the macronutrient composition of a carnivore diet would likely correspond to other very-low-carbohydrate diets (e.g., ketogenic, Atkins). For this reason, studies of these diets may provide relevant comparisons. In meta-analyses of trials for T2DM, low- compared with high-carbohydrate diets produced greater weight loss (40–42), lower HbA1c (40–46), and reduction in usage of glucose-lowering medications (41, 43, 45, 46), consistent with our observations. Although general dietary adherence and glycemic effects diminish over time (47), the findings of 1 recent nonrandomized trial suggest that a very-low-carbohydrate diet may be sustainable and efficacious when combined with high-intensity individual support (48).
Consistent with other low-carbohydrate diet studies (40–45), respondents reported a mixed blood lipid pattern: LDL-cholesterol, a major conventional cardiovascular disease risk factor, was markedly elevated whereas HDL-cholesterol and TG were favorable. However, LDL-cholesterol elevation, when associated with low TG, may reflect large, buoyant lipoprotein particles, possibly comprising a relatively low-risk subtype (49). Indeed, the low ratio of TG to HDL-cholesterol is suggestive of high insulin sensitivity and good cardiometabolic health (50). However, it is unclear whether this apparent benefit of the diet, together with the reported weight reduction and improved glycemic control (in the subset with diabetes), would counterbalance or outweigh any increased risk from LDL-cholesterol elevation. For individuals with a more extreme LDL-cholesterol response, drug treatment could be considered—an option that is generally more effective and better tolerated than drug treatment of insulin-resistance dyslipidemia.
Beyond macronutrient composition, elimination of allergenic, inflammatory, or other food components may provide potential health benefits to individuals following a carnivore diet. Food allergies and sensitivities are common, and predominantly related to plant foods (51). Some plant chemicals may produce adverse effects through other mechanisms, such as lecithin in beans, cyanogenic glycosides in certain seeds, and glycoalkaloids in potatoes. Indeed, >50% of survey participants started the carnivore diet to improve allergic, skin, or autoimmune conditions, or digestive health, and many reported improvements in inflammatory conditions and related symptoms. Conversely, dietary intake may be low for vitamins that are typically derived from plant foods (e.g., fruits, vegetables, nuts, seeds, and grains) or from nutritional fortification of staple foods (e.g., milk, juices, cereals, pastas, and other grain products) (52, 53). In addition, often unquantified phytochemicals (e.g., polyphenols, alkylresorcinols, phytosterols) are largely absent from the diet. Although these phytochemicals do not have DRIs, they have been linked to cardiometabolic benefits (54, 55). In people who eat meat only with exclusion of dairy (∼30% in this survey), calcium intake might also be low, as illustrated by the low intake and negative calcium balance in 2 Arctic explorers (28). Although essential nutrients can presumably be derived in sufficient amounts from animal foods (34), they are present in less commonly consumed parts of the animal, such as fat and organ meats (vitamins A and D), or bone (calcium), or may be reduced during food preparation (vitamin C) (34). Vitamin C is of particular interest, because meats are not formally considered a good source of vitamin C (i.e., they contain <10% of the DRI per serving) (56). Typical symptoms of deficiencies in these vitamins would include dermatological, cognitive, or neurological symptoms, as listed in Supplemental Table 1. A worsening or new presentation of these symptoms was reported in <2% of survey participants, whereas the majority of participants reported improvements, resolution, or no change—regardless of intake of vitamins, organ meat, or dairy. Given the self-reported nature of these findings, it remains unclear whether clinical or subclinical symptoms of nutrient deficiency are present. Research is needed to clarify the absence of perceived symptoms of nutrient deficiencies and the underlying biochemical processes that govern nutrient needs with the long-term consumption of a carnivore diet. It is possible that requirements for some micronutrients may be lower than those established in DRIs for the general population (57), related to remodeling of the gut microbiome, whole-body metabolism, and nutrient utilization in the setting of a low-carbohydrate carnivore diet, analogous to observations with a vegan diet (58).
Respondents reported high levels of satisfaction, and little social impact, from following a carnivore diet. Notably, medical providers were perceived as supportive, neutral, or unsupportive at generally similar proportions despite the discrepancy of the carnivore diets from dietary guidelines. Whereas meat is more expensive than grains and starchy foods, it may be less expensive on a caloric basis, depending on location and specific comparisons, than fresh fruits and nonstarchy vegetables (59), and cost may be in addition offset by decreased expenditure for diabetes and other medications. Our respondents spanned low to high income classes, suggesting against major financial barriers to the diet.
Our study does not address several important concerns related to consumption of an animal-based diet. Intensive animal production, typically with use of commodity grains and soy for feed, causes significant environmental harms and raises ethical issues about animal treatment. These concerns may be mitigated, to some degree, with integrated, pasture-based agricultural systems (60) and other interventions, such as the use of algal feed additives to reduce greenhouse gas production (61, 62). For context, industrial-scale, commodity grain monoculture may also cause substantial environmental impacts and loss of wildlife.
These findings must be interpreted cautiously in view of several major design limitations. Our survey assessed the perception of individuals following a carnivore diet and did not objectively assess diet, nutrient status, health-related outcomes, or confounding health-associated behaviors; and no physiological or biochemical measurements were obtained. These self-reported data are prone to recall and reporting bias, especially for the prediet information. Specifically, participants may have started the diet during a time of poor health and perceived subsequent regression to the mean as a benefit of the diet and being online community members may have resulted in over-reporting of adherence and perceived beneficial effects. Because no validated instruments are available to assess food intake frequency in a carnivore population, we used modified Likert scales. We did not assess portion size or other quantitative intake characteristics, nor did we use other dietary instruments for a more detailed characterization of the diet; these comprise topics of future investigations. Finally, the generalizability of the findings is unknown owing to the existence of selection bias, because individuals who experienced adverse effects or lack of health benefits are likely to have abandoned the diet and would therefore not have been captured in this survey. Adults adhering to a carnivore diet and responding to this online survey represent a special subpopulation with high levels of motivation and other health-related behaviors (e.g., physical activity, consumption of relatively whole, unprocessed foods). Therefore, respondents likely differ from the general population in ways that could influence the effectiveness, practicality, and safety of a carnivore diet. Related to this point, we did not obtain detailed information on diet and lifestyle habits before beginning a carnivore diet.
Our study reports on a large group of participants following a carnivore diet, with perceived health benefits and absence of symptoms consistent with nutritional deficiencies, providing insights into a poorly characterized dietary approach. However, the data are limited by several major design limitations inherent to the survey design. A clearer understanding of the long-term safety and benefits of a carnivore diet, exact dietary habits of people following this diet, and the generalizability of our findings, must await additional research.
Part 2 of this Q&A with our diabetes exercise expert covers pre-exercise glucose checks, exercise-induced hypoglycemia, and more.
Q: Please mention blood sugar level before as well as fluid and hydration intake before ANY exercise is crucial to predict glycemic response…. regular blood glucose checks are essential until you know how they respond.
A: The guidelines are that you should not begin the exercise with blood glucose >250 mg/dL (13.9 mmol/L) with moderate or high levels of blood or urinary ketones. If you don’t usually test for ketones, make sure you have enough insulin “on board” to counterbalance the glucose-raising hormones that get released during physical activity. The more complex the exercise is, the more of these hormones get released.
The guidelines also suggest that people should use caution during activities when starting with a blood glucose >300 mg/ dL (16.7 mmol/L) without excessive ketones, stay hydrated, and only begin if feeling well. For instance, if you take insulin and just ate a big meal, exercising right after when you may be experiencing a spike is usually okay because you have enough insulin in your body to bring the glucose levels down with activity.
As for hydration, drink adequate fluids before, during, and after exercise and avoid exercising during the peak heat of the day or in direct sunlight to prevent overheating. These precautions are essential when experiencing hyperglycemia (elevated blood glucose levels), leading to dehydration or autonomic (central) nerve damage that can impair normal heat dissipation during exercise.
Q: What are your recommendations for glucose testing before, after, or during exercise?
A: It depends on the individual. Adults with type 2 diabetes not taking insulin or oral sulfonylurea medications may not need to check because their blood glucose is unlikely to drop too low during activities—but they may want to check to be motivated by its ability to lower blood glucose, especially during post-meal spikes.
If you use insulin, it is essential to check before, occasionally during, and even at varying intervals after activities to prevent lows and highs and treat them more quickly. Frequent monitoring also helps establish usual patterns, trends, and responses that make it easier to predict what insulin regimen or food changes may be needed to balance blood glucose levels, especially if you are prone to developing late-onset hypoglycemia following an activity that is particularly long or intense.
Q: To avoid exercise-induced hypoglycemia, what are the normal glucose monitoring values before starting exercise? Is there a target glycemic range that you would recommend for those with Type 1 diabetes to begin exercise to prevent hypo during activity? Also, how can people recognize and respond to hypoglycemic reactions?
A: A good starting blood glucose level can vary with the activity, time of day, and expected responses. Most people like to start in the range of 70 to 180 mg/dL (3.9 to 10.0 mmol/L), but it depends. For example, if you’re going to do early morning exercise (before insulin or food), your blood glucose may rise due to the higher levels of insulin resistance at that time of day. Many people choose to exercise then so that their risk of going low is minimal. However, others prefer to exercise with slightly more insulin on board (but not too much) later in the day to avoid exercise-related highs, especially when doing more intense workouts. Some people give small amounts of insulin before doing intense early morning workouts to prevent going too high.
As for hypoglycemia, it can have various symptoms, including shakiness, visual spots, lethargy, extreme fatigue, and more. The symptoms can vary by person and the activity or time of day to make it more challenging. Learn to recognize your symptoms by confirming your blood glucose levels whenever any symptoms arise. Anything with glucose works fastest to treat a low, but you can use various carbohydrate sources and follow up with snacks with a balance of carbs, protein, and fat if lows tend to persist or recur over time.
Q: What resources would you recommend for additional information regarding clinical exercise programming concerning common diabetes medications?
A: There are two position/consensus statements with compiled information about being physically active with diabetes that would be particularly useful for diabetes medications and their impact on physical activity. One is an American Diabetes Association position statement from 2016 (PMID: 27926890), and the other is a consensus statement on type 1 diabetes from 2017 (PMID: 28126459).
Particularly for anyone using insulin or taking sulfonylureas (and possibly meglitinides within 2-3 hours of physical activity), it is essential to carry rapid-acting carbohydrate sources during activities to treat hypoglycemia and have glucagon available to treat severe hypoglycemia (if you are prone to developing it).
Q: Diabetes type 2 has been related to intramyocellular lipid accumulation. As fat oxidation is optimized at a low exercise intensity, would you recommend low exercise intensity over high-intensity exercise for patients with diabetes?
A: No. Any intensity of exercise that someone with type 2 diabetes can do is acceptable. While it is true that slightly more fat is used during lower intensities compared to higher ones, the primary fuel used by the body during most moderate or higher-intensity work is carbohydrates. Fat is the primary fuel during all recovery periods. Intramyocellular lipids, therefore, are the primary fuel used during rest periods, which is most of the time. Just try to maximize your total calorie expenditure from the physical activity without worrying about exercise intensity. (In other words, completely ignore anything that tells you that you are in a “fat-burning range” as it is incorrect and irrelevant.)
Q: What precautions need to be taken if there is peripheral neuropathy?
A: It is generally recommended that people with moderate to severe peripheral neuropathy (loss of sensation in the feet) limit or avoid activities that may cause foot trauma, such as prolonged hiking, jogging, or walking on uneven surfaces. It may be more appropriate for them to engage in non-weight-bearing exercises (e.g., cycling, chair exercises, swimming); however, they should avoid aquatic exercise with unhealed plantar surface (bottom of the foot) ulcers. It is also important to check feet daily for signs of trauma and redness. Other precautions include choosing shoes and socks carefully for proper fit and wearing socks that keep feet dry, such as some of the newer athletic socks that are polyester-cotton blends. Finally, neuropathy can affect both gait and balance, so they should avoid activities requiring excessive balance ability.
Q: I work with many folks who have kidney failure due to diabetes. Are there any precautions even though the client has been medically cleared?
A: Yes, the main precautions for these individuals revolve around avoiding exercise that causes excessive increases in blood pressure, such as heavy weight lifting, high-intensity aerobic exercise, and anything that causes breath-holding. For most, high blood pressure is common, and lower intensity exercise may be necessary to manage blood pressure responses and fatigue. The good news is that light to moderate exercise is possible during dialysis treatments if electrolytes are managed properly. A recent study showed that people on dialysis could safely engage in aerobic, resistance, or combined training with good outcomes on fitness, blood pressure, and metabolic function (PMID: 31865607).
Q: One of the complications you mentioned was peripheral arterial disease. The exercise pattern is less in these individuals. What do you think in that aspect when we can’t do higher intensity exercise? What pattern should we focus on?
A: Peripheral artery disease occurs when significant amounts of plaque are present in the blood vessels supplying the legs and feet. This blockage can cause pain and leg cramps, particularly during more strenuous exercise, due to reduced circulation and supply of blood and oxygen to those peripheral areas. While exercise may make things worse, the opposite is true, given the pain often associated with it. In addition, it can improve circulation with the formation of new, collateral blood vessels.
In general, the intensity of activity mainly impacts the recruitment of additional muscle fibers, specifically faster twitch fibers that are more anaerobic in nature than aerobic. Although fitness gains may be lesser with lower-intensity activities, doing anything at a low or moderate intensity still confers many health benefits, including increasing blood flow to areas with some artery blockage and enhancing oxygen consumption in engaged muscles (PMID: 28385410). Therefore, doing activities at any possible intensity should be encouraged, and walking is fine for most people to engage. People should be encouraged to try alternate activities when pain in their legs is more severe or intolerable during a given activity.
Q: Which fitness trackers monitor blood glucose levels, and how does this work?
A: If discussing only FDA-approved glucose monitors, at the current time, a person has to wear a separate continuous glucose monitoring (CGM) device like the latest ones from Dexcom that can transmit its readings to a fitness monitor, such as select Apple or Fitbit smartwatches, or apps like the one associated with Fitbit or other trackers. A compatible smartphone is required to display data on an Apple Watch, and the Freestyle Libre CGMs work through a linked phone app as well. This connectivity is currently being updated and enhanced, so check the latest devices for specifics on which ones connect and how to set them up.
Q: Do you have any apps you recommend to track exercise?
A: There are so many different apps, and most of the latest smartphones have accelerometers that can track steps or distances traveled. I use one called “Map My Walk” that tracks most types of activity (not just walks) and gives distance, time, and more. Many others also estimate calorie use. So it depends on what data sets are most important to you.
Sheri R. Colberg, PhD, is the author of The Athlete’s Guide to Diabetes: Expert Advice for 165 Sports and Activities (the newest edition of Diabetic Athlete’s Handbook). She is also the author of Diabetes & Keeping Fit for Dummies, co-published by Wiley and the ADA. A professor emerita of exercise science from Old Dominion University and an internationally recognized diabetes motion expert, she is the author of 12 books, 30 book chapters, and over 420 articles. She was honored with the 2016 American Diabetes Association Outstanding Educator in Diabetes Award. Contact her via her websites (SheriColberg.com and DiabetesMotion.com).
Diabetes Diet 
