A traditional slimming diet, which you put a little less energy into your mouth every day than your body uses, works just as well as trendy hip 5: 2 fasting diet, where you reduce your energy intake to almost nothing for 2 days of the week, while you keep consuming just as much calories as you body needs for the the remaining 5 days. German researchers, affiliated with the German Cancer Research Center in Heidelberg, published this in the American Journal of Clinical Nutrition. Their study is the largest trial of the effect of the 5:2 form of intermittent fasting to date.
The researchers divided 150 subjects with a BMI of over 25 into 3 groups.
During the 50 weeks that the experiment lasted, a control group did not change its lifestyle [Control].
A first experimental group went for 12 weeks on a traditional slimming diet [Constant], where the intake of energy was 20 percent below the the amount of calories a body burns. After this, the subjects in this group switched to a weight maintenance diet for another 12 weeks, consuming just enough energy to maintain their new body weight. In the remaining weeks the subjects were allowed to eat what & how much they wanted.
A second experimental group followed the same protocol. For the first 12 weeks of the study, they went on a 5: 2 fasting diet [Intermittent]. This meant that the subjects consumed enough calories to stay on weight for 5 days, while reducing their calorie intake to 20 percent of their maintenance levels for the other 2 days.
When the 12 weeks had ended, the 5:2 fasting diet group seemed to have had lost significantly more weight than the Constant-group. The 5:2 group also seemed to have lost slightly more belly fat than the Constant group.
As far as subcutaneous fat and waist size are concerned, the differences between the two weight loss groups after 12 weeks were not significant.
And after 50 weeks, the differences between the two groups had disappeared completely.
“This study indicated that intermittent calorie restriction and continuous calorie restriction are alternative energy restriction regimens for weight loss with comparable improvements to obesity-associated metabolic profiles, at least over 50 weeks”, write the researchers.
“Both regimens were well tolerated by the majority of participants and may be equivalent weight management approaches.”
“Further investigations are needed on the effectiveness, practicability, and safety of intermittent calorie restriction for patients with chronic diseases, such as type 2 diabetes, cardiovascular diseases, or cancer.”
“In addition, for some people it seems to be easier to be very disciplined on two days instead of counting calories and limiting food every day”, says research leader Tilman Kuhn in a press release. [sciencedaily.com November 26, 2018]“The same is also suggested in a current study comparing low-carb and low-fat diets, that is, reducing carbohydrates versus reducing fat intake while otherwise having a balanced diet.”
Am J Clin Nutr 2018;108:933-45.