An eating protocol called intermittent fasting is popular at the moment, primarily for reasons having to do with a biological process called autophagy and the (lack of) eating protocol’s supposed ability to improve health across a variety of categories. However, intermittent fasting has also become popular as a weightloss method, with past animal model research indicating that time-restricted eating may cause more fat loss than eating the same amount of calories spread throughout the day. A new study challenges this claim.
To understand the point of the new study, you first need to know about an intermittent study from Salk University, which found that two groups of mice fed the same quantity of calories experienced different degrees of weight loss — that the group put on a 16:8 intermittent fasting protocol lost more weight than the other group. The findings helped catapult intermittent fasting as a weight-loss trend.
This new study from UCSF builds upon that research, but focuses on humans instead of mice. A total of 116 people who had BMIs between 27 and 46 were randomly assigned to eat either consistently throughout the day or only during an 8-hour period daily, a protocol known as 16:8 fasting. After 12 weeks, the fasting group had an average weight loss of 2lbs and the non-fasting group had an average weight loss of 1.5lbs.
Ultimately, the weight loss difference between the two groups was nearly identical, with the researchers explaining that 16:8 intermittent fasting ‘is not effective on its own as a means of either losing weight or for improving key metabolic health markers.’ That latter point refers to things like HbA1C levels, lean mass, fasting insulin, fat mass, and similar markers.
The difference between the health markers in these two groups wasn’t significant, according to the study, ultimately indicating that calorie restriction throughout the day or in the form of intermittent fasting is unlikely to have any special metabolic benefits. The weight loss observed in those who stick to a 16:8 fasting protocol is simply the result of eating fewer calories overall, the study indicates.