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This Can Make or Break Your Weight Loss Goals

The many ways sleep deprivation can derail your healthy lifestyle.

Key points

  • Sleep deprivation increases your appetite, as well as your cravings for unhealthy snacks.
  • Your body responds to exercise differently when you are sleep deprived.
  • Dieting while sleep deprived makes something challenging nearly impossible.

We have all faced the challenge of choosing healthy foods when faced with temptation. We may eye that piece of cake with longing, knowing fruit would be a better option. The isolation and stress of the past year has also affected our approach to food and exercise, and many may be re-entering social events with self-conscious concern about changes in their appearance.

Certainly the market for weight loss programs, instruction manuals, apps and other tools is on the rise, with billions spent each year in the diet and fitness arena. However, there is one key factor in your day-to-day health that either smooths the path to a healthy weight, or, if ignored, creates significant barriers to desired changes.

This factor is sleep.

How do we eat differently when we are sleep deprived?

Have you ever noticed a surprising increase in your appetite after a poor night’s rest? Perhaps you pulled an all-nighter to finish that term paper, worked the late shift, or were kept awake to care for an ill child. The next afternoon, despite eating your usual lunch, you find yourself in the pantry, searching for a bag of chips or cookies. If so, you are not alone. Sleep deprivation has been shown to significantly increase both our hunger as well as our calorie intake the next day.

For example, in a study of healthy individuals given free access to food while limited to the same amount of physical activity, those who slept only 4.5 hours per night for 4 nights reported much higher levels of hunger, even as early as day two, compared to their well-rested peers. Additionally, those sleeping only 4.5 hours consumed as many as 300 more calories per day compared to those sleeping 8.5 hours.

To put this in perspective, if this level of sleep deprivation were continued for a full calendar year, this could result in an excess of more than 70,000 calories, or 10-15 pounds of weight gain.

Sleep deprivation also significantly changes what type of food we crave, namely, high-calorie sweets, carbohydrate-rich foods and salty snacks. In one study, consumption of these types of foods in those with inadequate sleep was increased by 30-40% compared to well-rested peers (protein, dairy and fatty food intake was also increased by 10-15% after sleep loss).

But by sleeping less, I'm more active, right?

Unfortunately, in our current societal framework of “work hard, play hard,” we may negatively judge those who sleep 8 hours a night, suggesting they aren’t maximizing their daytime productivity, or are slothful in some way. However, rather than “wasting time,” we are actually in a highly metabolically-active state during the physical immobility of sleep.

To illustrate this, researchers designed a study asking participants to undergo a 24-hour period of total sleep deprivation. They found that after staying awake for an additional 8 hours, those who didn’t sleep at all burned up fewer than 200 extra calories compared to peers who slept for 8 hours. Couple this with the earlier study’s findings, you see that this difference is likely cancelled out by the increased high-calorie food intake the next day.

Additionally, if you are sleep deprived, the resulting daytime fatigue and decreased energy may mean your physical activity decreases over the next day.

The end result? Overeating, under-exercising, and, eventually, significant weight gain.

Why Sleep Deprivation = Poor Food Choices

The more we learn, the better we understand the extremely high cost of inadequate slumber.

After an inadequate night of sleep, typically described in studies as <6 hours per night, it feels harder to make that healthy choice. In fact, when sleep-deprived, our brain is approaching that take-out menu as if preparing for famine, rather than simply seeking the next meal.

When trying to make any decision, we recruit several areas of our brain, particularly the prefrontal cortex (PFC). Think of this as your junk food conscience. When we are well-rested, the PFC resembles our favorite trainer at the gym, motivating us toward healthy choices, and giving us the power to resist those sweet or salty snacks. But after a night of sleep deprivation? Let’s just say our inner trainer chills WAY out.

The activity in the PFC decreases in sleep-deprived states, reflecting a “Go ahead, what’s the harm?” attitude. This is then coupled by an increase in activity in the more primitive, deep-brain structures, particularly the amygdala, which starts shouting “Yes, that cake smells amazing! How fantastic would it be to eat the entire thing?” This increased amygdala activity leads to an amplification in desire for highly caloric food.

To sum it up—when you are sleep deprived, your brain activity changes in a way that makes you feel more hungry and crave higher calorie foods. In other words, resistance is futile.

We have also learned that in addition to the changes in the brain after sleep deprivation, differences in circulating hormones after a night of poor rest will also affect levels of hunger and the amount we consume before feeling “full.”

The two most important hormones in sleep are called Leptin and Ghrelin. Though perhaps not the most mellifluous names, understanding their actions can help us better capture the effects of sleep deprivation. Briefly, Ghrelin triggers a strong sensation of hunger, encouraging you to forage, whether out in the wilderness, or in your fridge. Leptin, on the other hand, signals satiety, or fullness.

These hormones were evaluated in a study comparing individuals with 8.5 hours of sleep opportunity each night for 5 nights to their matched peers allowed only 4-5 hours of sleep per night. Both groups ate the same number of calories and were allowed the same amount of physical activity.

The results—those with sleep deprivation had increased levels of circulating Ghrelin (“I’m hungry!”), and lower circulating levels of Leptin (“I’m full.”) which meant it took them longer to feel satisfied during a meal. Perhaps you’ve read about the benefits of eating more slowly so you can better notice when you are satiated. Sleep deprivation messes up this signaling, and you may only feel content after a much larger meal. Dr. Walker, in his excellent book “Why We Sleep” quoted a colleague summarizing this affect as, “A sleep deprived body will cry famine in the midst of plenty.”

A Quick Aside about the Munchies and Exercise

A common side effect of cannabis involves an increase in appetite, and not necessarily for a healthy salad. Interestingly, we have endocannabinoids naturally occurring in our system, and these, like marijuana, also stimulate our appetite.

What happens after sleep deprivation? You guessed it. The levels of these substances are increased in our body, stimulating our appetites and increasing our desire to reach for a quick snack. Yet again, a night of poor rest interferes with our best laid plans for a balanced diet.

As it turns out, inadequate sleep even changes the way our bodies respond to exercise. For example, instead of burning fat during your 30-minute workout, a sleep-deprived body will instead sacrifice lean body mass. This decision, made without our conscious input unfortunately, likely harkens back to a time when our ancestors needed to hang on to the fat out of an evolutionary desire to stave off starvation. Essentially, the more fat we have stored, the better our energy backup plan in times of scarcity.

To Sum it Up

Certainly there are many reasons individuals are not well-rested. Allowing yourself an 8-hour sleep opportunity only leaves 16-hours each day to care for your family, earn a living, progress in your education, and so forth. This is simply not possible for many. However, understanding how our bodies and minds are affected by poor sleep, and the health challenges this can create, will hopefully motivate us to value our rest, and consider it a key feature of a healthy lifestyle.

Happy slumber, everyone.


Hanlon et al. Sleep restriction enhances the daily rhythm of circulating levels of Endocannabinoid 2-Arachidonoylglycerol. 2016. SLEEP 39(3): 653-664.

Leproult R and Van Cauter E. Role of sleep and sleep loss in hormonal release and metabolism. Endocr Dev 2010;17:11-21.

Walker, M. Why We Sleep: Unlocking the Power of Sleep and Dreams. Scribner, 2017.