The Most Important (and Overlooked) Weight Loss Tool

The Most Important (and Overlooked) Weight Loss Tool

Guess what one of the most important factors in weight loss is?! Hint: it’s not food or exercise.

Give up?

It’s sleep. Yes, sleep – and most of us aren’t getting enough of it.

Reading this you may think I’m crazy. I mean, how can something you do when you’re NOT eating have anything to do with your weight? Isn’t weight loss just about burning more calories than you eat?

Yes…but there are a whole lot of things that can affect the choices you make around food. Sleep affects a lot of them.

Lack of sleep increases your appetite.

How so? It turns out that sleep deprivation affects your hormones in undesirable ways. It decreases leptin (a hormone that signals that your body is full) and increases ghrelin (a hormone that triggers your appetite).1 In fact, a long-term study by Stanford’s School of Medicine found that people who were only getting 5 hours of sleep per night had an increase in ghrelin (appetite triggering hormone) of 14.9% and a decrease in leptin (satiety hormone) of 15.5% when compared with those getting 8 hours of sleep.2 These results were consistent regardless of the person’s gender, body mass index, eating, or exercise habits.

What does this mean for your real life? These hormonal effects will lead you to feel hungrier the next day (even when you’ve consumed an adequate amount of calories), making you more likely to overeat. And, you aren’t going to be craving healthy, nutrient-rich foods either. Instead, you will crave high sugar, high-fat foods because your brain is looking for quick energy to make up for the lack of sleep.

Lack of sleep may counteract your weight loss progress.

Do you ever feel like you’re eating well and exercising and still not losing weight? Lack of sleep could be the culprit. A study published in Annals of Internal Medicine found that participants’ who slept 5.5 hours a night lost less body fat and more lean body mass than when they slept 8.5 hours.3 They also reported being hungrier when they slept less, even though their food intake remained the same.

Another study at the University of Chicago found that sleep deprivation triggers a chemical signal in the blood that may increase the “hedonic aspect” of eating, making the food seem more pleasurable and satisfying. This makes it infinitely more difficult to resist highly platable (i.e. high sugar, high fat) foods. Your willpower never had a chance.

Why does this happen? Is your body just trying to work against you?!

Nope. It’s actually the opposite. Your body is trying to protect you. According to this study, it’s the result of an adaptation which triggers your body to conserve energy and increase food consumption when you’re in an environment with limited food availability (i.e. a diet) and lack of sleep.4 Thousands of years ago, this energy conservation process would have increased your chances of survival. In the modern world, it can undermine your weight loss progress and make you feel like you’re fighting an uphill battle.

Lack of sleep makes complex decisions difficult.

It may seem obvious that it’s more difficult to think clearly when you’re tired, but what you might not realize is the effect it can have on your decisions surrounding food. Sleep deprivation impairs activity in the frontal lobe of your brain – the part of the brain that is responsible for making complex decisions. It also increases activity in the amygdala – the brain’s reward center.5

What does this mean for you? It means that when you’re confronted by donuts in the breakroom, it will be much more difficult to weigh the costs and benefits associated with eating them. It will also increase their perceived reward value to your brain, making the donuts seem much more desirable and much more difficult to resist than they would have been with adequate sleep.

By now you’re probably realizing just how much sleep can affect your weight. But, what if you have little control over the amount of sleep you get in a night? For example, maybe you’re a new mom who’s sleep schedule revolves around her new tiny human(s).

Guess what? Just knowing the effects lack of sleep can have on your eating behavior can empower you to make better decisions. 

So, next time you find yourself gravitating towards comfort food when you’re tired, take a moment. Breathe. Remind yourself that your brain is unnecessarily going into survival mode. If you’re truly hungry, try to choose something with fiber, protein, and healthy fat that will keep you satisfied and make it less likely you’ll overeat.

Most importantly, if all hell breaks loose and you head for the nearest donut, muffin, cake, etc., don’t stress over it. You know now the factors that were involved and none of them were because of a lack of willpower. Just use it as a learning tool so that next time (there’s always a next time) you’ve set yourself up to make a better choice.

Have you noticed yourself craving certain things when you’re sleep deprived? Let me know in the comments below.


Taheri S, Lin L, Austin D, Young T, Mignot E. Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. PLOS Medicine. 2004;1(3). doi:10.1371/journal.pmed.0010062 [Source]
Brandt M. Obesity Linked to Hormonal Changes, Lack of Sleep. Stanford News. Accessed March 19, 2018.
Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity. Annals of Internal Medicine. 2010;153:435-441.
Penev PD. Update on Energy Homeostasis and Insufficient Sleep. JCEM. 2012;97(6):1792-1801.
Greer S M, Goldstein A N, Walker M P. The Impact of Sleep Deprivation on Food Desire in the Human Brain. Nature Communications. 2013;4(2259). doi:10.1038 [Source]

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