Eating twice a day, without restricting calories, may prevent metabolic syndrome.

Metabolic syndrome is a constellation of medical conditions that includes high blood pressure, high blood glucose, unhealthy cholesterol levels, and excess abdominal fat. Having metabolic syndrome increases a person’s risk of heart disease, stroke, and diabetes. Findings from a 2017 study suggest that eating two meals per day, without caloric restriction, induces inter-meal autophagy, potentially preventing metabolic syndrome.

Calorie restriction is the practice of long-term reduced dietary intake, typically characterized by a 20 to 50 percent decrease in caloric intake below habitual levels, without malnutrition or deprivation of essential nutrients. Evidence indicates that calorie restriction induces autophagy; however, adherence to the practice is challenging and often not sustainable.

Autophagy is a highly conserved adaptive response to stress that involves the sequestration and subsequent destruction of protein aggregates, pathogens, and damaged or dysfunctional cellular components. The primary goal of autophagy is to allow cells to adapt to changing conditions and external stressors, including nutrient scarcity.

The investigators examined the effects of different dietary patterns on autophagy in mice. They fed one group of mice two distinct meals per day (morning and evening), with each meal providing an equal number of calories. They fed another group of mice the same number of calories, but the mice were allowed to eat anytime during a 24-hour period. They monitored the animals' bodyweight and body composition and measured markers of autophagy and metabolic function.

They found that the two groups of mice weighed about the same at the end of the 16-month intervention, but mice that ate two distinct meals per day had less bodyfat and more muscle mass than those that ate freely all day. Mice that ate twice daily also exhibited increased expression of autophagy-related genes; browning of white adipose tissue (a phenomenon associated with improved metabolic function in mice); increased the expression of M2 macrophages, which exert anti-inflammatory properties; and improved aspects of metabolism.

These findings suggest that eating just two meals per day, without restricting total calories, induces autophagy between meals and improves aspects of metabolism. Watch this episode in which Dr. Guido Kroemer describe the effects of calorie restriction on autophagy.

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• Read our overview articles on autophagy and calorie restriction to learn more.