The Effectiveness of Your Diet Depends on How You Sleep

Last updated: November 18, 2019

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Perhaps you’ve experienced the increased need for snacks and heavy meals after a night of short or poor sleep. Sleep has been linked with our hunger and self-control, as well as metabolism. Scientists keep warning that inappropriate sleep can lead to weight gain, obesity, and diabetes due to hormonal imbalances it causes. What happens when you’re on a diet trying to lose weight and sleeping poorly? As it turns out, you don’t lose fat but rather – your muscles.

Diet effectiveness and sleep

Make a neat sleep schedule if you’re planning to go on a diet. Research suggests that sleep is crucial for losing weight the way you want to. Most of us want to lose some fat while retaining muscle mass.

What happens when you sleep poorly is that your body desperately holds onto your energy supplies (fat) because the lack of sleep deprives you of energy. That’s probably why you have an increased appetite when you don’t sleep enough. 

So if your body keeps the fat it has to burn something else and this is where your muscles suffer. 

The study published in the journal Sleep aimed to see how people will respond to a diet if they had enough (8.5h) and way too short (5.5h) amounts of sleep. They tested the same group of people on two occasions – once with normal and one with restricted sleep. Apart from controlling the length of their sleep, researchers also restricted their calorie intake.

The findings were these – dieters lost the same amount of weight in both cases. However, the composition of weight loss was not the same. Sleeping for 8.5 hours resulted in 50% of the lost weight being from fat and 50% from lean muscle which is normal, whereas sleeping for 5.5 hours a night resulted in the following: 75% of the lost weight came from lean muscle mass and only 25% from fat. 

Short sleep cut the fat loss to about half of what it would be had they slept enough. 

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Exercising may help keep more of your lean muscle, but restorative sleep is what builds your muscle mass; so your efforts could be in vain if you’re not sleeping properly. This is because restorative or deep sleep is easily lost – frequent wakings, sleep problems and disturbances, bad sleep schedule, bad food choice, and stress are only some of the things that make it hard to get deep sleep.

Sleep, insulin, and hunger hormones

Sleep restriction causes insulin resistance even in healthy young people whose calorie intake is limited. Sleep is responsible for healthy levels of blood glucose, insulin sensitivity, and cell metabolism in the human body. Some studies show that sleeping under five hours can metabolically age a person by 10-20 years, lowering their insulin sensitivity by about 16%. 

This means your glucose and insulin levels will be chaotic despite your diet. 

The study mentioned above included restricted calorie intake for a reason. Scientists wanted to prevent subjects from overeating because it is well known that sleep loss results in imbalances of hormones like ghrelin and leptin which control feelings of hunger and fullness. Sleep-deprived people are more likely to snack more often and eat larger meals; a behavior which, when paired with a slowed metabolism, may result in weight gain in the first place.

Ask yourself if you’re getting enough sleep and whether you had enough sleep when you were gaining weight because poor sleep can be one of the reasons you need a diet. Moreover, poor sleep can affect your diet negatively and make you even hungrier, just to make the whole process harder.

What you eat affects your sleep

There seems to be an infinite number of diets – from those that will require you to have a borderline vegan diet to almost completely carnivore regimens. What you choose is entirely up to you, although it’s a good idea to consult a specialist (not just anyone saying they are a specialist). Your doctor is a good starting point.

Here are some insights into how food affects your sleep

  • Diets with too much or too little carbs are bad for your sleep. The same goes for proteins. Try to have balanced meals.
  • Carbs make you sleepy but try to stick with the good carbs from wholesome foods.
  • Alcohol and caffeine – each disrupts sleep in a different way. Alcohol sedates you, reduces REM sleep, and causes frequent wakings. Caffeine, on the other hand, delays sleep time and messes with sleep quality even if consumed more than six hours before bed.
  • Dairy and meat are rich in calcium and tryptophan which help you relax and fall asleep. On top of that, yogurt and kefir are rich in good bacteria that have a beneficial role in stress relief and healthy sleep.
  • Foods containing melatonin are a great evening choice. Almonds, walnuts, milk, tart cherries, and berries contain this lovely sleep-inducing hormone.

Having some protein for dinner has proven to increase muscle mass in young and old people. This can also help you retain your lean mass.

How much sleep do you need?

It’s nice to know how diet affects sleep and how sleep affects diet, but what is sufficient sleep, anyway?

This depends on age, gender, overall health, genetics, and personal needs. According to the National Sleep Foundation, teens need 8-10 hours of sleep, while adults may need between 7-9 hours of slumber. Older adults over 65 may have somewhat shorter sleep needs. 

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While seven hours might be just enough for rare people, research shows that it’s not the case for the majority. So if you’re a hard-working active individual who claims to thrive on seven hours of sleep, think again and try to “test” yourself by allowing a longer sleep window for a few days. If you find yourself sleeping longer, that means that your body is trying to recover the lost sleep. Short sleep practice can be dangerous for your heart, brain, and overall health unless you’re one of those extremely rare lucky individuals whose genetics allows them to truly thrive on little sleep.

Additional resources

  1. Influence of sleep restriction on weight loss outcomes associated with caloric restriction https://academic.oup.com/sleep/article/41/5/zsy027/4846324
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