5 ways sleep affects your weight

More sleep may not melt pounds overnight, but research shows that good quality slumber can support weight management in other ways. Here’s the science on sleeping and the scale.
Published 21 April, 2021

Fluff the bed pillows and get ready for yet another reason to love a good night’s sleep. Those hours you spend conked out in dreamland? They could make a positive difference in your weight loss journey.

Growing scientific evidence suggests that sound sleep supports healthy weight management, both in the short term and over time. “Sleep ranks right up there with healthy eating and exercise when it comes to [attaining] healthy weight goals,” says Marie-Pierre St-Onge, PhD, director of the Sleep Centre of Excellence at Columbia University Irving Medical Center in New York City.

Does this mean you can lose weight simply by sleeping more? Not quite - experts aren’t suggesting that slumber automatically makes pounds disappear. But the amount and quality of shut-eye we get each night could potentially affect everything from our next-day snack choices to our mental capacity for following a meal plan. Read on for a nuanced look at how sleep can affect your weight.

1. Sleep influences appetite

If you feel ravenous after staying up too late, know that it’s not your imagination. “Reduced sleep dysregulates appetite hormones,” says Abhinav Singh, MD, a medical review panelist for and medical director of Indiana Sleep Center in Greenwood. Sleep deprivation is associated with increased levels of ghrelin, a hormone that helps signal hunger, as well as reduced levels of the hormone leptin, which is linked to feelings of satiety, Dr. Singh says. While there’s no “perfect” amount of sleep that suits everyone, a 2018 research review found that this hunger-stoking hormonal effect tends to kick in when sleep duration dips below seven hours.

2. Sleep may affect cravings

In addition to dialing up appetite in general, lack of quality zzz's may influence our food choices, and not in a way that makes us crave a plate of fresh veggies. “Sleep loss increases activity in brain areas associated with reward,” Dr. St-Onge explains. “These signals seem to increase motivation to seek foods that are high in [unhealthy] fat and calories.” Quality of sleep matters, too, she adds: in a small 2020 study of women published in the Journal of the American Heart Association, volunteers who reported sleeping poorly tended to consume more added sugars and fewer foods containing healthy unsaturated fats than those who snoozed more soundly.

3. Sleep can support workouts

It’s no secret that getting into an exercise groove can help people manage weight. The challenge is that being active takes mental and physical oomph - and being well rested is key to both. In a 2019 survey of 1,011 adults by the National Sleep Foundation, nearly half reported that sleepiness hampered their ability to exercise. Fortunately, there’s more to the story than that: previous research suggests a bidirectional association between sleep and activity levels. This means that sleep may encourage you to become more active, and becoming more active may support better sleep. If you’re feeling unmotivated to hit the gym, focusing on your zzz's may help workouts feel more doable.

4. Sleep can help you stick to a plan

There’s a reason you might feel like your whole world is in disarray after a few nights of tossing and turning: poor sleep can hamper executive functioning, the set of cognitive processes that help us organise our time and tasks, solve problems, and manage impulses, notes a 2017 report in the journal Nature and Science of Sleep. This can make a weight loss plan (or pretty much any plan) challenging to follow, Dr. Singh says. For example, a groggy brain may not have the bandwidth for healthy meal planning - leading you to grab a less-than-ideal lunch on the go - or for prioritising the yoga session you had hoped to fit into your hectic day.

5. Sleep is linked to metabolism

The stage of sleep characterised by dreams and rapid eye movement (REM) may be a factor in how many calories the body burns at rest. During REM sleep, heart rate increases and brain activity most closely resembles that of a wakeful state. All that action requires glucose as fuel, which leads to a higher resting metabolic rate, the energy a body needs for basic functioning, Dr. St-Onge says.

People cycle through REM and non-REM stages repeatedly during sleep, with REM periods getting gradually longer as the night goes on. That means if your sleep is cut short, you lose out on those extended REM stretches. A small study published in the journal Obesity found that volunteers who were roused after a mere four hours of slumber woke up with 2.6% lower resting metabolic rates compared with their baselines. “This could make weight loss or maintenance harder,” says Dr. St-Onge. More research is needed to determine actual effects on the scale.

Another metabolic note: compared with people who get adequate sleep, those who consistently get short sleep are more likely to exhibit decreased insulin sensitivity and increased concentrations of cortisol. This dual hormonal effect could raise a person’s risk of developing prediabetes or type 2 diabetes, an existing medical concern for many people living in larger bodies.

The upshot: can sleeping more help you lose weight?

Right now, there’s not enough evidence to state that sleeping unto itself can speed up weight loss. Growing scientific evidence does show, however, that falling short on sleep can affect your mood and mindset, as well as the hormones your body secretes and the foods you desire - all of which could lead to gaining pounds. Chat with your GP if tossing and turning persists: you deserve good-quality rest.