Are you among the 35% of Americans who don’t get enough sleep? If so, you’re doing yourself a huge disservice if you’re also hoping to lose fat or gain muscle. While you don’t necessarily lose weight while sleeping, a lack of sleep most definitely hampers both fat loss and muscle growth.

Why is this the case? Let’s take a look at why sleep is important for body comp.

Sleep and Appetite

Have you ever had a bad night’s sleep? Heck, I have! I have 3 young kids, 2 cats, a puppy, a business, and a cold brew addiction (see the part about 3 young kids). If you’ve ever slept poorly, you know how much it can throw off your routine the following day.

Sleep deprivation turns me into a crabby snack monster, and apparently this is not unique to me!

In one (very) small study of adults with BMI greater than 25, those who slept 8.5 hours per night lost 55% more fat than adults who slept 5.5 hours per night. While it’s difficult to draw conclusions from just one small study, a large body of research provides context for these results (1).

Whether you suffer from insomnia or are burning the midnight oil, sleep deprivation messes with your hormones. Specifically, it:

  • Increases levels of a hormone called ghrelin, which boosts hunger and cravings.
  • Decreases levels of a hormone called leptin, which promotes satiety and suppresses hunger.
  • Increases levels of a stress hormone called cortisol. Studies have linked higher cortisol levels with more food cravings, higher appetite, and increased likelihood of both insulin resistance and weight gain (2).

In other words, inadequate sleep throws the hormones that regulate your appetite out of whack. This increases the likelihood that you’ll eat more, give in to junk food cravings, and gain weight, especially over time.

Sleep Deprivation and Impulse Control

Are you thinking you’re out of the woods because you only sleep poorly sometimes? Think again.

Even one night of bad sleep alters activity in the frontal lobe of your brain–an area that plays a key role in decision-making. To add to that, sleep deprivation increases activity in the amygdala of the brain, which can make junk food feel suuuuuper rewarding. Super Size Big Mac value meal after a late night out? Don’t mind if I do.

Sleep Deprivation and Muscle Mass

As if an increased appetite paired with decreased self-control isn’t enough, sleep deprivation can mess with your gains.

Sleep feels relaxing and restful, but your body is actually hard at work while you snooze. Two important tasks that happen at nighttime? Muscle repair and growth.

Human growth hormone (HGH) is a chemical that speeds up muscle repair, promotes muscle growth, and burns fat. Production of HGH peaks during deep sleep, and there’s some evidence that suboptimal sleep hampers HGH production (3).

To add to that, our muscles receive more blood flow while we’re sleeping. Simply put, inadequate sleep limits your anabolic potential.

Can You Lose Weight While Sleeping?

Can you lose weight while sleeping? Perhaps. But you can certainly gain weight (and lose muscle) from not sleeping.

If you’re consistently sleep-deprived, try to work toward at least 8 hours per night. You’ll feel better, look better, and perform better at the gym.

We’ll provide some tips for promoting sleep in an upcoming post. In the meantime, we’d love to chat with you about the relationship between diet, sleep, and performance. Click here to schedule a free 15-minute nutrition intro, and to learn how we can help you implement some healthy lifestyle practices.