Matt returns with Part 2 of his series on sleep and weight gain. This time around, he teaches us how a lack of sleep not only makes you eat more food, but changes what types of food you want to eat, and eat to excess.

First, Matt describes how underslept individuals that are limited to 4-5 hours of sleep for several nights will experience a 33% increase in the desire to eat obesogenic, sugary treats. In addition, they will suffer a 30% increase in craving for heavy-hitting carbohydrates, like pasta and pizza, and a 45% increased desire for salty snacks!

Matt goes on to explain that your brain plays a role in this sleep loss-weight gain equation. In one of his experiments, a group of normal, healthy-weight individuals went through the study twice: once when sleep-deprived and once after a full night of sleep. After each condition, the individuals were placed inside an MRI scanner and shown different food types, and asked to rate how much they wanted each food item.

What they found is that the sleep-deprived brain changed markedly, shifting to a pattern of activity associated with what is called hedonic eating, or impulsive eating. Specifically, the prefrontal cortex, which is responsible for impulse control, was shut down by lack of sleep. As a result, the very primitive deep brain regions that drive excessive appetite become hyperactive and hyper-responsive to highly desirable, unhealthy food items, such as ice cream and donuts, rather than nuts or leafy greens.

He also reveals that staying awake across the night doesn't burn vastly more calories. You only burn about an extra 140 calories by staying awake all night relative to being asleep, yet you will eat more than twice that amount more in calories when sleep-deprived. Plus, you are less active when sleep-deprived, so you don't burn off those calories.

Worse still, Matt tells us that dieting becomes ineffective without sleep: 60% of the pounds you will lose come from lean body mass (such as muscle), and not fat. Specifically, when you are sleep-deprived, the body becomes especially stingy with fat, stubbornly refusing to give it up. In other words, you end up losing what you want to keep, which is muscle, keep what you want to lose, which is fat. Also, inadequate sleep increases levels of cortisol, which also makes your body store food as fats.

Matt concludes with an optimistic note by highlighting the fact that getting enough sleep is a scientifically proven way to help you regulate your appetite and a healthy body composition (a little bit less painful than going to the gym!?)

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

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#16: Sleep & Weight Gain – Part 2

The Matt Walker Podcast