People who follow an intermittent fasting approach to lose weight may be cheating without realising it, researchers have discovered.
Teams from the School of Science and Technology at Nottingham Trent University and the National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University wanted to explore why fasting at set periods works well for some and not for others.
The most popular fasting approach is the 5:2 diet, which involves people reducing their food intake for two days a week and then eating normally for the remaining five days.
However, intermittent fasting works better with some people than others, but the study team have now determined why.
Their trial involved monitoring a group of men for three days and comparing a low-calorie diet with a low-calorie day to see if any differences occurred. On the first day the men were only allowed to consume 700 calories over the course of the whole day. The participants’ hunger bouts were recorded before and after they ate, as well as any exercise they carried out.
The second day involved them following a very low-calorie diet and once again, having their physical activity levels measures. On the third and final day the men were allowed to eat an unrestrictive breakfast.
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The researchers found the participants consumed 6 per cent more food on the first day, and 14 per cent more at the unrestricted breakfast during the three-day study.
They believe this pattern of behaviour occurred because the men knew their food intake would be limited the next day and that hunger had very little to do with it.
Exercise was also impacted with the researchers finding physical activity was 11 per cent lower the day before the men followed the low-calorie diet and 18 per cent lower on the low-calorie day.
The research team said: “Our study highlights what and when compensatory behaviours occur. This information can be used to improve the effectiveness of intermittent fasting diets.
One of the researchers Dr David Clayton, senior lecturer at Nottingham Trent University, said: “Being more mindful when eating before and after a period of calorie restriction and incorporating exercise into diet plans, could help increase the likelihood of intermittent fasting leading to weight loss.”