While exercise and diet are two popular weight-loss strategies, many people overlook one of the most important keys for weight management: sleep. The quality of your sleep plays a crucial role in how your body senses hunger, handles stress, and approaches exercise and movement. Sleep deprivation can disrupt hormones, elevate stress, and even slow your metabolism, all of which can sabotage your weight management efforts.

Meet the Hunger Hormones 

Sleep primarily affects weight management by impacting two key hormones that regulate appetite and metabolism: ghrelin and leptin. Ghrelin is your body’s “hunger hormone,” signaling when you need to eat. Leptin is your “satiety hormone,” telling your brain when you’re full, signaling it’s time to stop eating.

Under normal conditions, ghrelin levels spike before meals and drop about an hour after eating, while leptin is produced by fat cells to communicate how much energy is stored. When you’re well-rested, these hormones are in sync, keeping hunger in check. However, when you’re sleep-deprived, this delicate balance gets disrupted.

What Happens When You’re Sleep Deprived

We all know a bad night’s sleep can leave you feeling groggy and unfocused—but the effects don’t stop there. Sleep deprivation sets off a chain reaction in your body that goes way beyond feeling tired. From hunger hormones to stress levels, a lack of rest can disrupt your body’s natural rhythms in ways that make it harder to maintain a healthy weight. Here’s what happens when you skimp on sleep.

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Your body defaults to hunger.

Sleep deprivation triggers a significant drop in leptin levels and an increase in ghrelin production. In simple terms, this means you’re more likely to feel hungry, even when you’ve eaten enough.

You may eat more than usual the next day.

Studies show that people who are sleep-deprived tend to eat an extra 500+ calories the following day. Without enough rest, your body’s cravings for quick energy sources (calories) skyrocket, leading to overeating.

You crave junk food.

Sleepless nights are more likely to leave you snacking more frequently on low-quality food (pizza, cookies, and ice cream instead of protein, nuts, and leafy greens). 

And unfortunately, it’s a vicious cycle: Eating processed food before bed tends to lower your sleep quality.

READ MORE: 8 Foods and Drinks For Better Sleep (And 4 To Avoid!)

Your energy system malfunctions.

Sleep deprivation also affects insulin sensitivity. Insulin helps your cells absorb glucose from the bloodstream for energy, but inadequate sleep makes your cells resistant to insulin signals. This results in excess glucose remaining in the blood, which is often stored as fat. 

You feel more stressed.

Less sleep equals more stress, and more stress can lead to less sleep — it’s a vicious cycle. In fact, one survey found that 43 percent of people reported that stress caused them to lie awake at night.

Cortisol, the hormone your body produces when under stress, isn’t all bad: It helps wake you up in the morning, also helps to lower inflammation when in normal amounts. However, when there are chronically high levels of cortisol it can disrupt your sleep — as well as your overall health.

Plus, consistently elevated cortisol levels can lead to increased appetite and cravings for high-calorie, high-fat foods. Additionally, cortisol can promote the storage of fat in the abdominal area, which is associated with increased health risks such as cardiovascular disease and diabetes. Furthermore, cortisol can interfere with the production of thyroid hormones, which are important for regulating metabolism. This can lead to a sluggish metabolism and difficulty losing weight.

Member Tip: Monitor your stress levels with Oura’s Daytime Stress feature—see if your Sleep Score correlates with your stress levels.

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