Is Sleep Better Than Exercise?

June 21, 2018
by Heather Huffman

Is Sleep Better Than Exercise?

There are few things more frustrating than trying to sift through mountains of conflicting weight loss advice, except perhaps putting the advice into action and seeing no results. Maybe it’s simply because I’m in my 40s now, but it’s a common complaint among too many people in my world: I’m watching what I eat, I’m exercising, and I still can’t lose those last 20 pounds.

Since becoming a sleep nerd, I’ve stumbled across a bit of information that was groundbreaking for me. On one level, it left me nearly weeping with relief. My limited success wasn’t solely because I suck. There was a legitimate reason I was hitting a brick wall with my health goals. On another level, I was incredibly frustrated the amount of research I’ve done to figure out how to correct my weight, and not one article had included this golden nugget of information: lack of sleep can make you fat.

From hormone imbalances, to insulin resistance, to the effectiveness of your workouts, sleep truly is the pivotal third pillar of health. Without it, the other two—diet and exercise—can’t properly do their job.

Our body systems are set in motion by an intricate balance of chemicals and hormones, each with a specific purpose. These hormones are regulated by a small portion of the brain known as the hypothalamus, which also plays a crucial role in the sleep/wake cycle and other important functions. A 2014 study showed that sleep deprivation was associated with hypothalamic disfunction in rats. Whenever you have an intricately balanced system, it’s never a good idea to take out the thing holding it all together.

One night of sleep deprivation also raises cortisol levels and reduces your immune system. That one definitely got my attention. I should say I cared because elevated cortisol levels are responsible for high blood pressure and increased stroke risk, but the truth is much shallower: cortisol is responsible for increased belly fat.

Cortisol, one of the main hormones we release when we’re in “fight or flight” mode, isn’t bad in and of itself. We need a certain amount of it to keep us awake, motivated, and responsive to our environment. When consistently elevated, though, it can have some pretty serious side effects, including:

  • Suppressed immunity
  • Hypertension
  • High blood sugar (hyperglycemia)
  • Insulin resistance
  • Carbohydrate cravings
  • Metabolic syndrome and type 2 diabetes
  • Fat deposits on the face, neck, and belly
  • Reduced libido
  • Bone loss

Cortisol levels are supposed to rise during the early morning hours then drop throughout the day, so they’re low at night before and during sleep. When cortisol gets unbalanced, it can leave you feeling the opposite: tired all day but wired and anxious at night.

Increased cortisol increases our appetite and enhances fat storage. So we’re hungrier, and our body is more likely to cling to fat. Once your cortisol levels get out of whack, it becomes a bit of a cycle: increased cortisol keeps you up at night, lack of sleep increases your cortisol. This article from Dr. Axe has some great tips for reducing your cortisol levels.

Also impacted by sleep is serotonin, a.k.a. nature's appetite suppressant. This powerful neurotransmitter curbs cravings and shuts off appetite, making you feel satisfied even if your stomach isn’t full. 

A study from the journal Sleep found that not getting enough sleep gradually desensitizes serotonin receptors. Our bodies need consistent sleep patterns to use serotonin. And when we feel like we’re low on serotonin, we tend to crave the foods that will quickly replace it: carbs. (Hello, comfort food.)

Leptin and ghrelin are the yin and yang of hunger hormones, with ghrelin stimulating hunger and leptin shutting your appetite off. Research shows that people who habitually don’t get enough sleep at night have reduced leptin, elevated ghrelin, and an increased body mass index (BMI).

It doesn’t help that when your body is sleep deprived, it suffers from “metabolic grogginess,” a term coined by University of Chicago researchers who analyzed what happened after just four days of poor sleep. (Something that’s really easy to do during the typical work week.) They found that during that time, our body’s ability to properly use insulin became completely disrupted, and insulin sensitivity of fat cells dropped by more than 30 percent.

To put it another way, lack of sleep alters our brain’s ability to use glucose, impacting our metabolism and causing weight gain.

Another, more disturbing, study showed that just ONE night of poor sleep had a greater impact on insulin resistance than six months of a high-fat diet.

As much as 75% of human growth hormone, or HGH, is released during sleep—that’s the hormone responsible for stimulating muscle growth and repair, bone building, and fat burning. When sleep is happening the way it’s supposed to, most of that HGH release happens during the first period of stage 3 sleep, which is about an hour after we go to sleep. This is the most restorative phase of sleep, when HGH sets to work restoring and rebuilding our body and muscles from the stresses of the day.

If we don’t get the necessary amount of sleep, our body doesn’t get the restoration it needs. Studies have also found that the timing of our sleep impacts our body’s ability to create hormones, so inconsistent or irregular sleep cycles can hurt our ability to repair ourselves. That matters when it comes to weight loss because exercise is what’s known as a hormetic stressor.

You see, not all stress is created equal. A little bit is good for us; it causes us to turn into something better. It’s when stress converts to chronic stress that it wreaks havoc on our bodies and minds. Hormetic stress is only good for you IF you give yourself a chance to recover. Under-recovery turns hormetic stress into chronic stress, the bad stuff.

When you exercise, you’re actually wearing your body down and creating microtears in the muscles. It’s the act of recovery from this process that builds the muscles up. Without recovery, you’re doing your body more harm than good, and proper recovery happens during sleep.

Sleeping less than seven hours per night can reduce or even undo the benefits of dieting, according to research published in the Annals of Internal Medicine. In the study, dieters were put on different sleep schedules. When their bodies received enough rest, half of the weight they lost was from fat. When they cut back on sleep, the amount of fat lost was cut in half—even though they were on the same diet. They also felt significantly hungrier, were less satisfied after meals, and lacked energy to exercise. Overall, those on a sleep-deprived diet experienced a 55 percent reduction in fat loss compared to their well-rested counterparts.

In fact, Stanford University performed a study where they followed a group of athletes for a time. They did nothing different for these athletes other than increase their sleep and they saw marked improvements in performance.

This could be due, at least in part, to the fact that when we’re sleep deprived, we’re more receptive to pain. So we not only don’t work out as hard, what little we do feels worse.

I remember reading somewhere that statistically, sleep is more effective than CrossFit when it comes to burning fat. I jokingly pointed this out to a CrossFit-loving friend, saying it was a great relief to me because I’m much more likely to sleep than I am to try CrossFit. He replied with, “I do both.” Not surprising, given his current physical shape.

I’d so dearly love to be able to sleep my way to being lean, but I know it’s not as simple as that.

As with anything that matters, there is no shortcut to being healthy. I can’t wave a magic wand and suddenly have the body and energy level I desire. Sure, it can be done in three steps; they’re just not simple ones.

  1. Eat healthy, whole foods
  2. Move your body, every day
  3. Get plenty of quality sleep

I know, that’s kind of a brat answer. Each one of those comes with a myriad of decisions and contingencies, but there is no skirting around any one of those pillars of health. I say this as I munch on a Twizzler, with my backside planted firmly in the same chair it’s been in for seven hours and my eyelids propped open with toothpicks.

It’s not an easy path, but it’s one we owe it to ourselves to try.