For mammals it’s not just what we eat, but when we eat is important, because our metabolism is tuned to daily sleep/wake cycle. It has previously been shown that mice fed high fat food within a restricted time period during the dark phase, when they are active, gain less weight than mice eating the same amount of food freely available.

New research finds that an eating schedule with “weekend cheating”, something that is applicable to humans, was just as affective at preventing weight gain. This and other benefits of time-restricted feeding in reversing obesity and metabolic disease are reported in in Cell Metabolism by a research group lead by Dr. Satchidananda Panda of the Salk Institute for Biological Studies in La Jolla, California. The authors suggest that in humans, a similar approach, confining eating to our active daytime period might combat obesity and metabolic disorders like diabetes, hepatic steatosis and hypercholesterolemia.



The research team tested in mice a variety of diets that are known to cause obesity in humans. Restricting eating to a 9 hour window during the dark phase diet reduced weight gain in mice fed high fat and high sucrose diets compared with ad libitum feeding of the same foods. When the feeding period was increased, the weight gain also increased, indicating that at least 12 hours of fasting is needed to protect from obesity. Weight loss was seen in previously obese mice switched to time-restricted feeding and these mice maintained their weight. Using MRI imaging the researchers showed that there was less fat in the time-restricted feeding groups.



For high fat diet the mice that “cheated” and were allowed ad libitum food on weekends, had 48% less fat than those allowed food all the time. That occasional changes in feeding pattern do not disrupt the benefits during the week was supported by the fact that the gene expression in mouse tissues obtained on the weekend, resembled the mice which were maintained on time-restricted feeding.

The earlier in life that mice were switched from ad libitum feeding to time-restricted feeding the better the body weight normalized. At a molecular level, the time-restricted mice showed differences in markers of fat storage, cholesterol, insulin resistance and the “satiety hormone” leptin.



In the United States more than one-third of people are obese, which contributes to diabetes, heart disease and cancer. Since time-restricted feeding does not focus on calorie counting, it may be easily adapted to the modern human lifestyle as a treatment for obesity.