Part-time fasting works, nutritionists at the Hebrew University of Jerusalem conclude from an animal study. The researchers discovered that mice allowed to eat during a four-hour period per day were slimmer than mice that were allowed to eat whenever they wanted, even when both diets contained the same total number of calories.
The researchers’ experiment, the results of which were published recently in FASEB Journal, lasted 18 weeks. In this period the researchers gave half of their lab animals standard feed, containing little fat. [LF] The other half of the animals were given a high-fat diet. [HF] Mice put on weight quickly when given food that contains a lot of fat.
Half of animals in both groups were allowed to eat whenever they wanted. [AL] The other half of both groups were only allowed access to food during a four-hour period each day. [RF] During that interval the mice in the RF groups consumed as many calories as the mice in the AL groups, but they put on weight less quickly.
Animal study: slimmer and healthier with part-time fasting
The figures below show that the AL-LF mice became less fat than the AL-HF mice. That’s to be expected. But both the RF-LF mice and the FR-HF mice were much slimmer than the animals in the AL groups.
The RF mice moved a little more than the AL mice, but that small difference in exercise is not enough explain why the RF animals were so much lighter. The researchers think that part-time fasting reduces weight because it stimulates fat burning in the cells. The figure above, for example, shows that part-time fasting activates the AMPK enzyme. AMPK helps cells to go over to using fat as an energy source.
The mice in the RF groups were healthier, mainly because their insulin sensitivity increased.
“The timed HF diet leads to increased insulin sensitivity and fat oxidation and decreased body weight, fat profile, and inflammation contrary to HF-diet-fed mice but comparable to LF-diet-fed mice”, the researchers write. “Because an HF diet is difficult to abstain from, the timing of meals can be suggested for individuals seeking weight loss and better reset metabolism.”