Sleep Loss Limits Fat Loss

A number of people I know train really hard in the gym. And they are focused in the kitchen too which is even better. But come Saturday night and without hesitation, they are out weekend after weekend. Which means they’re missing out on sleep. And that’s not good. You’re about to find out why.

Sleep Illustration
Illustration by Peter Oumanski.

Rest and adequate sleep is very important and it will help you burn fat.

Inadequate Sleep:

When you deprive yourself of sleep, you will produce higher levels of the ghrelin hormone and lower levels of the leptin hormone. Higher level of ghrelin promotes hunger and retention of fat.

Adequate Sleep:

Leptin is the hormone that signals the body to use fat as an energy source when it doesn’t have enough food in the system for energy (i.e. while you are dieting). If your leptin levels are low, your body will burn less fat. And as a consequence, your metabolic rate will drop.

In a study by the University of Chicago, 10 slightly overweight volunteers went on a 2 week diet. The food intake was exactly the same. In the first study, the volunteers got around 8 hours of sleep a day. In the second study, the volunteers got around 5.5 hours of sleep a day.

At the end of the 2 weeks, BOTH times, the volunteers lost an average weight of 6.6 pounds. But here’s the catch. During the diet with 8 hours of sleep, the volunteers lost 55% more fat than during the diet with 5.5 hours of sleep.

During the diet with 8 hours of sleep, they lost 3.1 pounds of fat out of the 6.6 pounds of lost weight. During the diet where they only had 5.5 hours of sleep, they only lost 1.3 pounds of fat out of the 6.6 pounds of weight. Their behaviour and caloric intake was the exact same, only difference being the sleep.

Sleep Illustration
Illustration by Peter Oumanski.

To conclude, less sleep means you are more likely to lose less fat and more muscle. And that’s why I want you to burn fat and not lose muscle in your weight loss journey. Because otherwise you could be losing weight without getting noticeably leaner. And vice versa, don’t get all worked up over the figure on the scale as you could well be building muscle while losing fat, yet the scale numbers aren’t changing.

With summer just around the corner, a lot of people will have sleepless nights, of that I am sure. I haven’t asked before but do share this post if you think it will benefit others and get them to subscribe to my newsletter so they don’t miss further inside tips and much more.



  • Reply
    Kelly F
    26th March 2017 at 00:52

    I always feel very hungry the day after a night out.
    Never realised would have thought hormones are at play and what impact it all has.
    Thanks for sharing this!

    • Reply
      Cornel Ene
      29th March 2017 at 15:51

      Very happy to hear it has helped you Kelly. Drop me an email if there are any particular topics of interest to you and I will make sure to cover them in future posts.

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