How sleep affects weight loss

How sleep affects weight loss has been researched in numerous studies, and the findings are quite impressive.

The fact that something as simple as sleep can have such a massive impact on our health is fascinating. In this article we aim at exploring how sleep influences our weight and why.

How sleep affects weight loss

There isn’t just one mechanism through which sleep affects our weight. There are many variables but it all comes down to the duration and quality of sleep.

Research suggests that less sleep tends to be related to a higher body mass index and a higher chance of obesity, diabetes and other eating related pathologies.

However, the reasons behind these effects are not yet fully understood, but there are a few theories that can shed some light.

There are many things that happen to us during our sleep. Amongst these things, hormone regulation is a top priority.

What dictates when to feel hunger and when to feel that we had enough to eat and that we should stop? Hormones do.  

So, let’s take a short look at nutrition, in order to understand how and why sleep will have something to say about it.

Nutrition 101

Every living creature needs food to survive and prosper, humans are no different. The fact that in our modern society we ended up eating too much inevitably led to disease related to overeating.

Ghrelin and Leptin are the hormones that regulate hunger and satiety.

Ghrelin is produced by cells found in the stomach. It is the “hunger hormone” that we heard so much about and that gives the signal to feel hungry.

The more ghrelin there is, the hungrier we feel. It stimulates parts of our brain to increase appetite but it also does some other interesting stuff. It is an active participant in the circadian rhythm, but sadly we don’t yet know what it’s role is.

The adipose cells are the ones that make Leptin. You probably already guessed that this means that your fat cells are making a hormone. So, if you thought that fat has no other purpose in life than to annoy you, you were wrong. Fat is very useful to us, and producing leptin is just one of its many benefits.

When we eat, we should reach satiety once we have enough, and we should do this with the help of leptin. Because when leptin is secreted it tells our brain to stop eating.

However, sometimes people develop leptin insensitivity. This is a condition similar to insulin resistance which forces the pancreas to produce more and more insulin because cells have become accustomed to it.

Leptin resistance is often found in people, who suffer from obesity, but it can be reversed and getting enough sleep plays a major role in that.

How sleep influences leptin and ghrelin

Sleep influences many hormones. It regulates them with mechanisms that aren’t yet fully known.

What we do know[i] so far is the fact that short sleep duration, frequently interrupted sleep (by issues such as sleep apnea) and insufficient sleep leads to problems with leptin and ghrelin.

For example, sleep apnea was found to be correlated to a higher level of leptin[ii]. Even if you would think that this should be good, and that people with more leptin feel less hungry, it is not.

Higher leptin levels leads to leptin resistance, which translates in a person who feels hungry even after a meal.

However, in healthy individuals, a shorter amount of sleep is related to a lower level of leptin and a higher level of ghrelin.

This study shows that cutting sleep by only two hours, for two days can make you hungrier than you should be.

How sleep influences appetite

We already talked about how lack of sleep can mess with our hormones and make us feel hungry because of this. But another interesting fact is that when we are sleep deprived, our choice of food is not the best.

Lack of sleep pushes us to choose foods with a high caloric index[iii]. Even if we are not conscious of it, this happens because our brain wants us to gain weight. It is not a choice that we would normally make, but we do it regardless.

This may be due to our evolution, when in the early human society sleep deprivation was related to a higher caloric consumption.

How sleep influences exercise

Every day we burn through the calories that we consume. The average person needs as much as 2000 calories. But how many calories does a person with sleep issues need?

People who sleep less may need a few more calories in order to stay active during the hours when they should rest.

However, the circadian rhythm still influences our metabolism. The body temperature will be lower and the metabolic rate will plummet with it. And, regardless we will still consume more calories due to the process that we explained earlier.

Those who suffer from different sleep pathologies like insomnia or sleep apnea, tend to spend less time exercising. They don’t lead a lifestyle that is as active as that of those who sleep well.

This means that people with insomnia will burn less calories and will increase even further the risk of obesity.

Nevertheless, life loves irony. Maybe that is why exercise was shown in many instances to promote sleep[iv], to be an alternative remedy to insomnia[1] and to considerably lower the incidence of sleep apnea[2].

It is a vicious circle in which people with sleep difficulties don’t exercise because they feel tired. But exercising would improve their sleep and make them feel less tired during the day.

Weight loss, exercise and sleep are tightly knotted together, and attempting to repair one of these issues might start a series of events that would considerably improve the other problems.

If you want to lose weight, and you know that you have trouble sleeping, getting better sleep will help you lay the foundation of weight loss.

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[1] https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/209315

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5344097/

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[i] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4131947/

[ii] https://www.hindawi.com/journals/omcl/2018/5137947/

[iii] https://pubmed.ncbi.nlm.nih.gov/23922121/

[iv] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4341978/