It is impossible to overstate the importance of sleep. In my clinical practice, if a patient comes to me with a goal of weight loss or body recomposition and is sleeping fewer than seven full hours a night, I will say, in not so many words, that she is wasting her money if she’s not also committed to improving sleep duration and quality. Recent studies, since replicated, have confirmed that sleep deprivation (which means fewer than six hours of sleep) for a single night leads to an unintentional ingestion of an extra 400 to 500 calories the following day, and those additional calories almost always come from carbs.
Multiply this by a few nights, and you’ve got yourself a spare tire in a matter of weeks. Already overweight? Same rules apply: you are seriously hurting your chances of dropping extra weight when sleep deprived. Ghrelin: The Hunger Hormone Another hormone affected by sleep is ghrelin. Secreted by the stomach, ghrelin tells your brain when it’s time to be hungry. Your ghrelin level increases just before meals or when the stomach is empty and decreases after meals or when the stomach is stretched.
This hormone can also impact your behavior: when mice and humans are injected with ghrelin, the number of meals consumed increases. Ghrelin surges with just a single night of sleep debt. 13 This may be why one night of sleep deprivation will provoke, on average, an excess intake of 400 to 500 calories that day, mostly from carbohydrates, coinciding with increased inflammation, high blood pressure, and cognitive problems.
Aside from getting more sleep, how can we make ghrelin work for us? Eating fewer (but larger) meals throughout the day trains your body to produce less of the hormone. Science has now revealed that the advice to eat small, frequent meals to “stoke the metabolic flame” is bunk: metabolic chamber studies—when volunteers live in a room outfitted with instruments that measure how their bodies use air, food, and water under different conditions— show that whether you eat two meals a day or six your metabolic rate is exactly the same.
This is liberating because the approach of eating fewer and larger meals provides lifestyle flexibility, allows us to feel full, reduces decision fatigue, and helps keep the amount of time insulin is circulating to a minimum. Be aware, though, that as you adjust to fewer and larger meals, it may take at least a few days for your stomach to stop sending out signals saying “It’s time to eat!”