#15: Sleep & Weight Gain – Part 1

02/14/22 • 12 min

2 Listeners

Matt kicks off a two-part series all about sleep, eating, and weight gain.
He starts by introducing two appetite-regulating hormones: leptin and ghrelin. Matt explains how leptin sends a signal of fullness, to your brain. When leptin levels are high, your appetite is reduced, and you feel satisfied by the food you eat. Ghrelin does the exact opposite. It revs up your hunger, so when your ghrelin levels are high, you don’t feel satisfied by the food you ate, so you want to eat more.

Matt tells us that when you’re not getting enough sleep, the levels of these two hormones are affected in unfortunate ways, causing you to feel less full and more hungry. Specifically, sleep loss decreases leptin levels by 18%, yet increases ghrelin levels by 28%!
So when you are not getting enough sleep, the body losses the fullness signal AND suffers an increase in hunger levels. The combined consequences? Your appetite rockets up!

It’s also been discovered that levels of endocannabinoids --a class of cannabinoids we naturally produce ourselves -- increase sharply in response to a lack of sleep. As a result, your hunger levels increase even more (as you may know, cannabinoids are part of the reasons that cannabis gives you the munchies).

Adding up all of these effects, Matt describes how this lack of sleep causes people to consistently overeat. Usually somewhere between 250 to 400 extra calories each and every day!

Snacking also becomes a problem. For example, if you present a group of people with a large meal of over 1,000 calories, then give them the option to keep snacking, under-slept individuals will continue to snack, consuming an additional 200 to 300 calories relative to those who’ve been getting a full eight hours of sleep.

This all begs the question: is there a reason why your hunger goes into overdrive when you are under-slept? Matt explains one plausible theory from an evolutionary perspective, based on the fact that when animals are in a starvation state, the brain keeps them awake longer so they can forage further. Therefore, when the brain doesn’t get enough sleep, it thinks we may be in a state of starvation and increases our desire for food.

Finally, notes what's coming in part two: that insufficient sleep not only increases how much you eat but changes your food preferences, and changes how your bodies deposit the extra calories we take on as our hunger increases, relevant to body fat accumulation.

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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Adding up all of these effects, Matt describes how this lack of sleep causes people to consistently overeat. Usually somewhere between 250 to 400 extra calories each and every day!

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.

So, make your way over to Athletic Greens, and take advantage of this incredible deal. And, as always, if you have thoughts you’d like to share, please reach out to Matt on

Previous Episode

#14: Temperature – Part 2

In the previous episode, Matt described the role of temperature in helping us fall asleep. In this episode, Matt teaches us all about the role of temperature in helping us stay asleep across the night, and then more effectively wake up the following morning.

First, Matt takes us back to the body temperature suit experiments that were able to warm or cool different parts of the body. Matt explains that, using this same method, when you continue to cool the body throughout the first and middle parts of the night, enhance the ability of individuals to stay asleep more soundly across the night, increase the amount of deep sleep, and boost the electrical quality of that deep sleep.

Matt explains why a warm bath or shower before bed helps you sleep, perhaps for the opposite reasons you think. It is not that you get warm and toasty ready for bed. Instead, when you get out of the bath or shower, all of the blood races to the surface of your skin. As a result, your core body temperature plummets, enabling you to fall asleep faster and stay asleep more easily.

Matt also discusses how external ambient room temperature impacts our sleep at night. He notes that the optimal temperature for sleep at night for the average adult is between 16-18 degrees Celsius, or 61-65 degrees Fahrenheit, although everyone will be a little bit different, of course.

Finally, Matt explores the effect of temperature on waking up. He notes that as you move into those late morning hours of sleep, particularly as you start to enter the REM sleep-rich phases of your sleep cycle later in the morning, your central brain temperature rises significantly.
Indeed, it is in the last 30 minutes before people would naturally wake up in the morning that their body temperature starts to increase markedly. Matt goes on to describe how this increase in temperature is a signal that triggers the beginning of the awakening process.

Related to this, Matt notes that waking up can be challenging for many people, especially if you're not sleeping in synchrony with your chronotype. However, Matt suggests that one way you can facilitate the process of waking up more effectively is by trying to warm up the ambient temperature of the bedroom in the last 30 minutes before your alarm goes off. So if you have a smart thermostat, try to program it to increase the temperature to around 21 degrees Celsius or approximately 70 degrees Fahrenheit in the last 30 minutes before your alarm goes off.

The bottom line is that many of us don’t realize how important temperature is to falling asleep, staying asleep, and enjoying an enlivened awakening the next morning.

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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Next Episode

#16: Sleep & Weight Gain – Part 2

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.