PUBLIC HEALTH COLLABORATION: WHAT TO LOOK OUT FOR WHEN STARTING A LOW CARBOHYDRATE DIET

 

FOR EVERYONE

As you start a low carbohydrate diet your kidneys get better at excreting salt thus you will usually find that you lose a lot of water from the tissues of the body.  This can make you instantly slimmer, particularly around the legs, but also can give some cramps in the muscles when you exert yourself.  Be aware of this and add extra salt to your food, and drink plenty of water.  When you are on a low carbohydrate natural foods diet you will be consuming considerably less sodium chloride, which is present in many processed foods including sweet ones.  Bread for instance has a lot of added salt that most people are completely unaware of, therefore feel free to be liberal with the salt cellar.

 

BLOOD PRESSURE

Blood pressure comes down, partly due to less water retention, but also due to lowered natural insulin levels in the body.  As the weight comes down as well, blood pressure tends to drop.  For most people who are not on any antihypertensive drugs they may feel slightly lightheaded from time-to-time.  This can be abolished by adding more salt to the diet.

For people who are on medication to reduce their blood pressure they should have their blood pressure measured by their general practitioner and cut back on medication on embarking on a low carbohydrate diet if their blood pressure is under 140/90.  After a few weeks on a low carbohydrate diet they will be adjusted to a lower level of blood pressure.  Thereafter blood pressure only requires to be checked on several occasions with each extra half stone of fat loss.

It is helpful to buy your own blood pressure monitor as measurements done when you are relaxed at home tend to be more accurate than those undertaken in a surgery.

As many blood pressure medications have more than one use, and different effects on the body, it is worth discussing with your general practitioner which ones would be better to cut out altogether or which ones could be reduced in dose.  This is because certain drugs such as ACE inhibitors and sartans have an extra protective effect on the kidney and this can be important for diabetic patients. They also help improve heart function in cardiac failure.

Beta-blockers are sometimes given to people with atrial fibrillation, or who have had a heart attack, or who suffer from angina, and continuing these may be a priority for some individuals.

BLOOD SUGAR REDUCTIONS

Blood sugar reductions happen rapidly with a low carbohydrate diet.  This is mainly due to the lack of sugar and starch being turned into blood glucose.  This has several effects.

The most pronounced and rapid effect could be on the eyesight.  The lens of the eye adjusts to a particular blood sugar and if the level goes suddenly up, or suddenly down, your vision can become blurry, particularly for reading print.  It is worthwhile avoiding getting new spectacles for about 6 months to give time for the lens of your eye to adjust otherwise you can end up having to get another pair of spectacles at a very short interval and this can be rather expensive.

 

INSULIN and ORAL HYPOGLYCAEMIC DRUG USERS NEED TO TAKE EXTRA PRECAUTIONS

Type 1 diabetics will have been using insulin from the time of diagnosis.  Increasing numbers of Type 2 patients are going on insulin as their pancreas needs more support as time goes on.  A rapid change in pattern of sugar and starch intake can give dangerously low levels of blood sugar unless the insulin dose is proportionately reduced from the outset of the diet.  The amount of reduction will depend on how high your blood sugars run normally, and how strict your low carbohydrate diet is.

For many people who are taking insulin, or sulphonylurea drugs which also have a marked blood sugar reduction effect, starting on a moderately low carb diet of 100g or so a day may cushion the effect somewhat.

Most diabetics will need to cut their insulin quite dramatically, particularly if they go on less than 50g of carbohydrate a day.  It is normal to have to cut insulin by a half or even two thirds in some individuals.

A close eye on blood sugar monitoring needs to be done and we would recommend that, for particularly people who are operating machinery or driving, they start a low carbohydrate diet over a period of holiday when there are other people around who can assist them should they have low blood sugars, and also people to undertake driving on their behalf.

 

Your own general practitioner or hospital endocrinologist is the best person with whom to discuss your planned reduction in insulin or sulphonylurea medications.

Many patients on sulphonylureas are able to stop these drugs completely prior to starting a low carbohydrate diet and thus remove the risk of low blood sugars completely.  People who use insulin however are not able to do this and must have a degree of background insulin to prevent them developing dangerously high blood sugars and ketoacidosis.

  The normal blood sugar ranges between 4 and 7 at most times.  Drivers must not drive unless their blood sugar is at least 5, and they should re-check their blood sugar after every 1-2 hours of driving.  To treat a hypo use 15-20g of glucose and do not drive till blood sugars are completely normal and you have fully recovered.

Setting an alarm to check blood sugars in the middle of the night, and taking blood sugars at 2½ hourly intervals through the day is advised in the first few days for insulin users.

The normal correction dose is one unit of rapid acting insulin for every 2.5 units of blood sugar elevation. This can be helpful to know if you have cut down your insulin doses a bit too much.

Aiming for blood sugars between 6 and 8 mmol can be a safe strategy in the first 2 weeks after starting a low carbohydrate diet.  Thereafter the blood sugars can be tightened up when insulin requirements are more predictable.  To prevent blood sugars going up and down unpredictably it is best to stick to 3 main meals a day and avoid snacking.

EDUCATIONAL COURSES

For insulin users and people on sulphonylureas it is best to fully understand the implications of a low carbohydrate diet and know how to control your blood sugars and insulin as well as having a good grasp of carb counting prior to undertaking a low carbohydrate diet.  There are many educational resources on the web to do this.  Some of these resources are Dr Bernstein’s Diabetes University on you tube, diabetes.co.uk website and Low Carbohydrate Course which is web based, and diabetesdietblog.com which has two written courses.

LONG TERM

Although it can be daunting to think about the initial difficulties that can occur with a low carbohydrate diet, the long term benefits of improved blood sugars, weight, blood pressure and lipids make the outlook for pre-diabetics, the overweight and people suffering from diabetes much brighter indeed.  It is worth educating yourself about your condition and how to effectively use a low carbohydrate diet to change your health destiny.  The extra planning that you need to do for meals, more frequent shopping for fresh ingredients and often increased expense are worth the long term health benefits.

ALCOHOL

Alcohol can be a pleasant part of life.  Many alcoholic drinks are high in sugar, such as beer and sweet wines, and also cocktails.  These need to be eliminated for success in a low carbohydrate diet.  Spirits such as whisky, gin and vodka have less impact on the blood sugar, and dry red and white wines are also suitable.

For insulin users, and particularly Type 1 insulin users however, alcohol can tip them into unexpected hypoglycaemia if they are consuming more than 1-2 units of alcohol without a corresponding increase in dietary carbohydrate.  This is because alcohol limits the ability of the liver to manufacture glucose, and also blood sugars tend to run much more towards the normal range, around 4.6, when diabetes undergoes an apparent reversal on a low carbohydrate diet.

EXERCISE

Exercise is a very beneficial and pleasant adjunct to a low carbohydrate diet for increased mood and health.  For insulin users and those on medication such as sulphonylureas, adding exercise into the regime early on in the stages of a low carbohydrate diet add an increasing layer of complexity to blood sugar management.  We therefore recommend that unaccustomed exercise is avoided for the first 2 weeks until blood sugar stability is achieved.

 

Dr Katharine Morrison