The Surprising Link Between Sleep and Weight Loss

Few lifestyle factors have a greater effect on health and well-being than sleep. The hours you spend snoozing touch every part of your body, from your brain to your heart to your metabolism. A lack of sleep throws a wrench in all these body systems, which can spell trouble if you’re trying to lose weight. 

“There’s a direct link between insufficient sleep and obesity,” says Joel Evans, MD, chief of medical affairs at The Institute for Functional Medicine. Studies show that people who consistently clock fewer hours than needed are more likely to gain weight, have a higher body mass index (BMI, a measure of body fat), and develop obesity than those who get plenty of rest. 

Why? And how can you tell if sleep is at the root of your weight struggles? Read on to find out.

How Is Sleep Connected to Weight Gain?

Sleep deprivation impacts weight in several ways. 

“A lack of sleep naturally provides more opportunities for eating due to the larger window of wakefulness,” explains Marissa Toussaint, MD, a board-certified obesity medicine physician. 

Beyond that, insufficient sleep wreaks havoc on your hormones. There are two in particular that affect hunger and weight: ghrelin and leptin. “Sleep deprivation causes a decrease in leptin, which is your satiety hormone, and an increase in ghrelin, which is your hunger hormone,” Dr. Evans says. With more ghrelin pumping through your body and less leptin on hand to dampen it, you’ll be more likely to overeat.

And once you do, you probably won’t reach for fruits and vegetables. In one study, sleep-deprived women ate 500 to 800 calories more per day than their well-rested counterparts, and most of those extra calories came from sugar and saturated fats. When you shortchange yourself on the sleep you need to function, your body craves more calories than usual because it assumes there’s an urgent reason you’re awake, Evans explains. While that may have helped people survive in the days before grocery stores and cars, these days eating excess calories more often only results in weight gain.

Sleep deprivation dulls your brain’s prefrontal cortex — an area that regulates your emotional response to food — and enhances the brain’s limbic system, which heightens your awareness of food reward. “In other words, sleep deprivation can increase emotional eating and make less healthy foods more appealing,” Dr. Toussaint says. 

Poor sleep is also stressful for your body, increasing levels of the stress hormone cortisol, “which also causes weight gain,” Evans says. Cortisol can contribute to weight gain in different ways, one of which is its disruption of insulin, a hormone that helps control blood sugar. Over time, this disruption can increase insulin resistance, a condition where your body stops responding well to insulin, per the National Institute of Diabetes and Digestive and Kidney Diseases. 

Ultimately, this affects blood sugar regulation and fat storage. “Chronically high levels of cortisol and insulin contribute to the buildup of excess fat, particularly in the midsection,” Toussaint explains.

How Do You Know if Sleep Is Affecting Your Weight? 

If you’ve gained or struggled to lose weight and you’re wondering if sleep has anything to do with it, consider whether you experience low energy levels, increased cravings for sugary or high-fat foods, or both, Toussaint says. These are potential signs that your sleep habits aren’t working in your favor.

Try tracking your sleep for a few weeks, Evans suggests. You can use your smartwatch or a sleep tracker like the Oura Ring or Whoop wristband, or go old-school with a Notes app or pen and paper. Jot down approximately how many hours of sleep you get per night, whether your sleep was solid or fragmented, and how often you got up (if at all).

If you see that you’re regularly clocking fewer than seven to nine hours per night, there’s a good chance that sleep — or lack thereof — is having an effect on your weight. Exactly how many hours of sleep you need depends on many factors, such as age, activity level, and health status, Toussaint says. Therefore, it may take some trial and error to find your optimal sleep duration.

Certain health conditions can also interfere with sleep. Evans advises speaking with your doctor if you’re up frequently at night to pee or if you wake up short of breath. You may have urinary tract issues or sleep apnea, a sleep disorder in which breathing repeatedly stops and starts. Treating these conditions can help you sleep better when paired with healthy sleep habits, which ultimately helps your weight loss efforts. 

How to Improve Sleep for Greater Weight Loss

The cheapest, most straightforward way to help your weight loss efforts is to get seven to nine hours of sleep per night, Evans stresses. Plus, you’ll lower your risk for heart disease, high blood pressure, and obesity, and improve your focus and thinking abilities, per the National Heart, Lung, and Blood Institute.

Focusing on your sleep hygiene (also known as good sleep habits) will help you score more precious hours. To improve sleep, prioritize checking the following boxes.

1. Stay Consistent

“Having a consistent bedtime schedule and routine can set the stage for restful sleep,” Toussaint says. That means sticking with the same evening rituals, bedtime, and wake time daily, whether you’re going to work or it’s a day off. 

2. Limit Screen Time at Night

Phones, televisions, tablets, and computers are chock-full of blue light. Research has found that this wavelength prevents your body from releasing melatonin, the hormone that makes you sleepy. For that reason, Toussaint recommends avoiding screens beginning at least one hour before bedtime.

3. Watch Your Alcohol and Caffeine Intake

Alcohol and caffeine also disrupt sleep — caffeine because it’s a stimulant, and alcohol because it interferes with optimal sleep rhythms. Steer clear of both when bedtime nears. One study found that people still felt the effects of caffeine consumed six hours earlier, resulting in a loss of more than one hour of sleep.

4. Calm Down

Encourage restfulness by practicing calming activities before bed. Listen to soothing music, meditate, perform deep breathing exercises, take a warm bath, or write in a journal. 

Once you start sleeping regularly, you’ll notice more energy during the day and hopefully a small weight loss effect after a couple of weeks as well, Evans says.

 

Editorial Sources and Fact-Checking

• Papatriantafyllou E et al. Sleep Deprivation: Effects on Weight Loss and Weight Loss Maintenance. Nutrients. April 2022.
• Zuraikat FM et al. Measures of Poor Sleep Quality Are Associated With Higher Energy Intake and Poor Diet Quality in a Diverse Sample of Women From the Go Red for Women Strategically Focused Research Network. Journal of the American Heart Association. February 17, 2020.
• Insulin Resistance and Prediabetes. National Institute of Diabetes and Digestive and Kidney Diseases. May 2018. 
• How Sleep Works: Why Is Sleep Important? National Heart, Lung, and Blood Institute. March 24, 2022.
• Lockley SW et al. High Sensitivity of the Human Circadian Melatonin Rhythm to Resetting by Short Wavelength Light. The Journal of Clinical Endocrinology & Metabolism. September 1, 2003.
• Drake C et al. Caffeine Effects on Sleep Taken 0, 3, or 6 Hours Before Going to Bed. Journal of Clinical Sleep Medicine. November 2013.