According to the latest study, giving your body enoough time to digest food is critical for optimal health and a good sleep. It is the case even if you eat all fat diet, versus have access to food at all times.

Scientists at the Salk Institute for Biological Studies in California recently published a study in the journal Cell Metabolism that investigated one important aspect of this problem. Their question: which is more important—what you eat or when you eat? For example, what would happen if you could only eat between the hours of 9 am and 4 pm? Would you gain less weight and be healthier overall even if you ate a high fat diet? Their answer was “yes.”

Mice were given free access to either a standard, nutritionally-balanced chow or a chow that was high (61% of calories) in fat. Some mice were allowed total access to the food at all times. Some mice were only allowed access to their assigned diet for an eight hour window during the early phase of their normal active period. As anyone would have predicted, the mice given total all-day access to a high fat diet (the standard American diet) developed obesity, diabetes, and metabolic syndrome and altered sleep-wake rhythms.