If you’re trying to lose weight, the amount of sleep you get may be just as important as your diet and exercise.
Unfortunately, many people aren’t getting enough sleep.
About 35% of US adults are sleeping fewer than 7 hours most nights, according to the Centers for Disease Control and Prevention (CDC). Getting fewer than 7 hours of sleep at night is considered short sleep.
Interestingly, mounting evidence shows that sleep may be the missing factor for many people who are having difficulty losing weight.
Here are 6 reasons why getting enough sleep may help you lose weight.
1. It may help you avoid weight gain associated with short sleep
Short sleep — usually defined as fewer than 6–7 hours — has been repeatedly linked to a higher body mass index (BMI) and weight gain.
One analysis of 20 studies including 300,000 people found a 41% increased obesity risk among adults who slept fewer than 7 hours per night. In contrast, sleep was not a factor in the development of obesity in adults who slept longer (7–9 hours per night).
Another study found short sleep duration to be significantly associated with greater waist circumference, which is an indicator of the accumulation of belly fat.
Other studies have found similar results.
Studies have also found similar associations in children and adolescents.
In a recent review of 33 observational and intervention studies, short sleep duration was associated with an increased risk of obesity. Interestingly, for every additional hour of sleep, BMI scores decreased.
Another review of many observational studies found short sleep duration was associated with a significantly higher risk of obesity in these different age groups:
- Infancy: 40% increased risk
- Early childhood: 57% increased risk
- Middle childhood: 123% increased risk
- Adolescence: 30% increased risk
One major review found that short sleep duration increased the likelihood of obesity in children by 30–45%.
Though lack of sleep is only one factor in the development of obesity, research suggests it negatively affects hunger levels, influencing a person to consume more calories from high fat and high sugar foods.
It may do this by affecting hunger hormone levels, increasing ghrelin, which makes you feel hungry, and decreasing leptin, which makes you feel full.
Ghrelin is a hormone released in the stomach that signals hunger in the brain. Levels are high before you eat, which is when the stomach is empty, and low after you eat. Leptin is a hormone released from fat cells. It suppresses hunger and signals fullness in the brain.
Poor sleep may also negatively affect the sympathetic nervous system, resulting in increased levels of cortisol — a hormone related to stress.
It may also suppress various hormones, such as levels of insulin-like growth factor 1 (IGF-1). IGF-1 is linked to greater fat storage.
Additionally, many sleep disorders, such as sleep apnea, may get worse with weight gain. Unfortunately, this can lead to a cycle of poor sleep leading to weight gain and weight gain leading to poor sleep.
Summary: Studies have found that poor sleep is associated with weight gain and a higher likelihood of obesity in both adults and children.
2. Quality sleep may help moderate your appetite
Getting enough sleep may help prevent increases in calorie intake and appetite that can happen when you’re sleep-deprived.
Many studies have found that people who are sleep deprived report having an increased appetite and a higher daily calorie intake.
One review of studies found that those who experienced sleep deprivation consumed an additional 385 calories per day, with a greater than usual proportion of calories coming from fat.
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Another study showed that sleep deprivation led to significant increases in hunger, food cravings, portion sizes, and chocolate and fat intakes.
The increase in food intake is likely caused partly by the effect of sleep on the hunger hormones ghrelin and leptin.
When you do not get adequate sleep, the body makes more ghrelin and less leptin, leaving you hungry and increasing your appetite.
Summary: Poor sleep may increase appetite, likely due to its effect on hormones that signal hunger and fullness.
3. It may help you make better food choices
Getting a full night’s sleep may help you make healthier food choices.
Lack of sleep alters the way your brain works and can affect decision-making. This may make it harder to make healthy food choices and resist tempting foods.
In addition, it appears that the reward centers of the brain are more stimulated by food when you are sleep-deprived.
For example, one study found that sleep-deprived participants had greater reward-related brain responses after viewing images of high-calorie foods. Interestingly, they were also more likely to pay more for food than those who had adequate sleep.
Therefore, after a night of poor sleep, not only is that bowl of ice cream more rewarding, but you’ll likely have a harder time practicing self-control.
Another study showed that sleep deprivation led to increased smell sensitivity to high-calorie foods and greater consumption.
Furthermore, lack of sleep may lead to poorer food choices, such as a higher intake of foods high in calories, sugar, and fat, to compensate for feeling a lack of energy.
Summary: Poor sleep can decrease your self-control and decision-making abilities, as well as increase your brain’s reaction to food. Poor sleep has also been linked to an increased intake of foods high in calories, fats, and sugar.
4. Sleeping early can prevent late-night snacking
Going to sleep earlier may help you avoid the late-night snacking that often comes with staying up past your bedtime.
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Pushing your bedtime later means you’re staying up longer, which creates a larger window of time for eating, especially if it has been many hours since dinner.
For example, if you ate dinner at 6:00 p.m. and you stay up until 1:00 a.m. every night, you’re likely going to be hungry at some point between dinner and bedtime.
If you’re already experiencing sleep deprivation, you may be more likely to opt for less nutritious options. That’s because sleep deprivation can increase your appetite and craving for high-calorie, high-fat foods.
Interestingly, late-night eating is associated with greater weight gain, a higher BMI, and decreased fat oxidation — making weight loss more difficult.
What’s more, eating too close to bedtime, especially large meals, may decrease the quality of your sleep and make your sleep deprivation even worse. In particular, those with acid reflux, indigestion, or sleep disorders may want to limit food intake before bed.
Ideally, try to limit your food intake to 2–3 hours before bed. That said, if you’re hungry, consider having a small, protein-rich snack, such as Greek yogurt or cottage cheese.
Summary: Poor sleep can increase your calorie intake by increasing late-night snacking, portion sizes, and the time available to eat.
5. Potential benefits for your metabolism
Getting enough sleep may help you avoid decreases in metabolism that can happen when you haven’t gotten enough sleep.
Your resting metabolic rate (RMR) is the number of calories your body burns when at rest. It’s affected by many factors, such as:
- muscle mass
Interestingly, sleep duration may also affect your RMR.
One study including 47 participants looked at how sleep restriction affected RMR. The experimental group slept normally for 2 nights (baseline) followed by 5 days of sleep restriction with 4 hours per night.
Finally, they had one night of “catch-up” sleep, during which they spent 12 hours in bed.
During the 5 days of sleep restriction, participants’ RMR significantly decreased compared with the baseline. However, their RMR returned to normal after the “catch up” sleep. The control group had no significant changes to their RMR.
This study suggests that sleep deprivation may reduce RMR, but that you may be able to bring your RMR back up by getting proper sleep for at least one night.
On the contrary, other studies have found no changes in metabolism with sleep loss and suggest energy expenditure may increase with short sleep because you’re awake for longer.
Therefore, more research is needed to determine whether and how sleep loss affects metabolism.
Lack of sleep may also suppress fat oxidation, which is the breakdown of fat cells into energy.
One study found that sleep deprivation resulted in significantly lower basal fat oxidation in people of different ages, sexes, and body compositions. However, RMR was not affected.
It also seems that poor quality sleep may decrease muscle synthesis, which may lower RMR.
One small study showed muscle synthesis decreased significantly by 18% and plasma testosterone by 24% after one night of poor sleep. Additionally, cortisol significantly increased by 21%. Collectively, these conditions contribute to the breakdown of muscle.
However, this study was small and only 1 day long, which are major limitations. Furthermore, other studies suggest that sleep deprivation doesn’t affect muscle repair and growth. Thus, longer and larger studies are needed.
Summary: Poor sleep may decrease your resting metabolic rate (RMR), although findings are mixed.
6. Sleep can enhance physical activity
Sleep and physical activity have a close two-way relationship. A lack of sleep decreases physical activity, and lack of physical activity may lead to worsened sleep.
Numerous studies have shown that regular exercise can decrease the time it takes you to fall asleep and increase the overall quality of sleep across all age groups.
Furthermore, a lack of sleep can cause daytime fatigue, making you less motivated to exercise and more likely to be sedentary.
In turn, you may expend fewer calories in a day when sleep-deprived than you would after a proper night’s rest. This can make achieving a calorie deficit for weight loss more difficult.
What’s more, a lack of sleep can negatively affect your athletic performance by decreasing your:
- reaction time
- fine motor skills
- muscular power
- problem-solving skills
It may also increase your risk of injury and delay recovery.
Ultimately, getting enough sleep is key to staying active.
Summary: Getting enough sleep may increase your motivation to be more active and enhance your athletic performance, both of which can contribute to weight loss. Interestingly, being physically active can also improve your sleep.
If you’re trying to lose weight, not getting enough sleep can sabotage your efforts.
Suggested read: How many hours of sleep do you really need?
A lack of sleep is linked to poorer food choices, increased hunger and calorie intake, decreased physical activity, and ultimately, weight gain.
If your weight loss efforts are not producing results, it may be time to examine your sleep habits. Though individual needs vary, most adults need around 7–9 hours of sleep per night.
Getting some much-needed rest may make all the difference in helping you achieve your weight loss goals.
Tonight, try to be in bed at least 30 minutes earlier than you usually are. If you’re not able to sleep, read a book or listen to a podcast instead of scrolling on your phone or watching TV.