Adapted from BMJ 28 June 2025 Intermittent fasting as a nutritional tool by Semnani-Azad et al.
A study aimed to find out what effect intermittent fasting diets had on cardiometabolic factors compared to unrestricted diets or continuous energy restriction.
99 RCTs involving over six thousand people were examined. Compared to no restriction in food intake (no dieting), both continuous energy restriction and intermitting fasting led to reduced body weight.
The only type of intermittent fasting diet that produced more weight loss than continuous food restriction ( eg traditional calorie counting) was the alternate day fasting method. Otherwise, whatever method was adopted, the cardiometabolic improvements were similar for the other dietary types.
Some people find it easier and more simple to stop eating certain meals entirely rather than count calories or undertake other forms of food limitation. For caloric restriction, a deficit of 30% was usually able to be maintained in the first three months, when motivation was high, but fell below 10% after 12 months.
This study looked at differences between no dietary restriction, overall calorie restriction, fasting on alternate days, time restricted eating, and whole day fasting. Although alternate day fasting produced the most weight loss after 24 weeks, the amount was only 1.29kg more per participant. Fat lost from the viscera is particularly helpful for people who have fatty liver disease. People with type one and two diabetes, overweight, obesity, metabolic syndrome and metabolic dysfunction such as fatty liver, were included in this study.
This study does not establish any particular dietary strategy as being superior, but does suggest that alternate day fasting be considered as a worthwhile option. The best diet for an individual is one that they can stick to and so widening the options may be helpful.
Diabetes Diet 