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 the 7-9 hours recommended sleep a night, with probably up to a third of us regularly getting less than that.
Interestingly, mounting evidence shows that sleep may be the missing factor for many people who are having difficulty losing weight.
Here are the 6 reasons why getting enough sleep may help you lose weight.
1. 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.
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.
2 Poor sleep affects your appetite
Though lack of sleep is only one factor, research suggests it negatively affects hunger levels, influencing us 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.
3 Sleep, hormones and your nervous system
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 apnoea, 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 .
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.
4. Sleep and calorie intake
Poor sleep may increase appetite, likely due to its effect on hormones that signal hunger and fullness.
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.
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.
5. May help you make better food choices
Getting a full night’s sleep may help you make healthier food choices. 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.
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 centres 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.
6. Sleeping early can prevent late-night snacking
Poor sleep can increase your calorie intake by increasing late-night snacking, portion sizes, and the time available to eat.
Going to sleep earlier may help you avoid the late-night snacking that often comes with staying up past your bedtime.
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 2–3 hours before bed and if you’re hungry, consider having a small, protein-rich snack, such as Greek yoghurt or cottage cheese.
7. 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: age, weight, height, gender and muscle mass.
Lack of sleep may also suppress fat oxidation, which is the breakdown of fat cells into energy.
8. Sleep, muscle and fat
One study found that sleep deprivation resulted in significantly lower basal fat oxidation in people of different ages, sexes, and body composition. 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.
9. 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, endurance and problem solving skills.
It may also increase your risk of injury and delay recovery so clearly getting enough sleep is key to staying active.
If you’re trying to lose weight, not getting enough sleep can sabotage your efforts.
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.
If you are looking for more advice, nutritionist Patrick Holford’s article will be helpful.
The Power of Sleep