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How exactly do you stay in shape? There’s so much information going around but the key ingredients seem to be a healthy diet, coupled with aerobic exercise and strength training. Simple, right? Well, not so much… What’s the other key ingredient for losing weight, staying fit, and building muscle? The short answer – sleep. Think about when you’ve had a poor night’s sleep, for whatever reason, and then think about having to go to gym the next morning and stick to your low carb, low fat, or Mediterranean diet. More than likely, none of those things are going to be on your wishlist. And that’s because sleep massively contributes to our overall wellbeing and brain activity. Below we’ll take you through the ways in which sleep deprivation affects diet and exercise, and explain why getting enough sleep is crucial.

1.     Increased Appetite

You’ll find that when you don't get enough sleep, your appetite is greatly increased. This is your body trying to find a way to recoup the energy spent during periods of poor sleep and is largely a hormonal response. In a study that looked at healthy people and the effect of sleep deprivation on their levels of leptin, ghrelin, and cortisol, the findings showed how leptin levels were lowered, while spikes in ghrelin and cortisol were identified. Leptin is the hormone that suppresses appetite and causes us to not be so hungry, while cortisol and ghrelin do the opposite. This hunger can also lead to poor dietary choices as your energy levels are in flux.


In short, your tiredness can make you go straight for the Red Bull, cake, and sweets in a vain attempt to stuff yourself with enough energy to stave off your increasing hunger.

2.     Slower Metabolism

Our metabolism goes into a slump when asleep, as is the same for many other body processes. But the problem with a lack of sleep is that this slump can continue throughout the day. This is due to your body making alterations to glucose metabolism which can cause weight gain. The problem is that your energy expenditure will decrease. It’s in a slump like this where your whole system is not operating at an optimal level that weight is gained and laziness sets in.

3.     Reduced Muscle Mass

Sleep deprivation studies have indicated that muscle mass is perceived to decrease because of inadequate recovery. Surprisingly, muscles don’t grow in the gym, but when we recover, and this recovery also takes place while we sleep. A decrease is activity of protein synthesis pathways is highlighted can be a reason why you’re not seeing results.


4.     Fat Loss vs Fat Gain

This one is a bit of an eye-opener regarding the importance of sleep. Studies show that “the amount of sleep contributes to the maintenance of fat-free body mass at times of decreased energy intake”. In a correlation between sleep, diet, and fat loss a 55% difference was found between sleep deprived individuals and those who slept well.

When you’re sleeping, your body is managing the fat in your body, indicating that a main cause of obesity could be due to poor sleep patterns.

5.     Change in Fat Cells

Insulin is a hormone responsible for absorbing nutrients from food and regulating blood sugar. If insulin sensitivity is poor then we’ll have trouble digesting foods, turning them into fat and storing them in organs like the liver. Sleep deprivation can cause our insulin sensitivity to become lower.

This means that  you might be eating more food of poorer quality because you lack energy, but due to insulin resistance all you’ll be more likely to gain weight and putting yourself at higher risk of getting diabetes.

6.     Bad Food Choices

When you haven’t had enough sleep, you’ll not only crave foods that you shouldn't, but your portion sizes are more likely to be bigger as well. That not only means a risk of obesity and diabetes, but derailing your healthy diet altogether. Your brain activity is also lowered, leading to poor choices.

7.     Gym Decline

We’ve spoken a lot about how sleep deprivation affects your diet and the way your body operates, so now let’s talk specifically about gym. If you train regularly then you’ll already know what a bad night’s sleep can do to your training the next day: tired, fatigued, non-committal, and downright dead. But not only can it lead to injuries, but a greater perceived exertion – even though your heart rate and metabolic rate stays the same.

In short, when you’re fatigued and lifting weights or spinning, 10 minutes could feel like 30. You’ll be gasping for air and incapable of lifting your regular weight, or doing the same number of sets. And with poor gym days, comes a loss of motivation and added stress.


In conclusion, a healthy, balanced diet and regular exercise are needed when you have goals in mind pertaining to weight loss, muscle gain, and overall health. But the third factor is also sleep. If you’re deprived of sleep, or suffering from sleep apnea, then you simply won’t be able to perform at an optimal level throughout the day.

Ways to combat this and stop the rot:


  • Turn your electronics off an hour before you sleep
  • Keep the lights off as the darkness will draw you in deeper
  • Don’t drink caffeine in the late afternoon
  • Try not to exercise right before bed time – although it’s different for everyone
  • Before you sleep, de-stress your life in any way you can. Listen to music that relaxes you, take a long bath, meditate, or sit down with that book you’ve been promising yourself you’re going to start, and embrace sleep because it is necessary for your health, disposition, and wellbeing


Sleep Training Workout Nutrition Wellbeing Fitness Diet


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