Sleep deprivation can lead to loss of fitness - Shape Up Fitness & Wellness Consulting

Fitness & Weight Loss Through Sleep

Things You need to Know

  • Sleep deprivation can affect your body’s insulin sensitivity
  • You will feel an increase in appetite
  • You will feel a decrease in satiation after taking in food
  • Cortisol levels don’t change in total numbers but you have more exposure throughout the day.
  • Testosterone production can be reduced by 10-30% after just a couple of days with sleep deprivation.
  • Sleep cannot be ignored if you want to be successful

Effects of Sleep Deprivation on Insulin

Even one night of partial sleep deprivation can have a negative impact on your body’s insulin sensitivity. What does that mean for you? If your body does not respond well to insulin it is more likely to store energy in form of fat. Secondly your body will increase the insulin output which could lead to an early exhaustion of the pancreatic beta cells, the ones producing insulin and bring you one step closer to being a diabetic.

Increased Appetite, Increased Hunger

Sleep deprivation can lead to a decrease in leptin. Leptin is a master hormone in charge of hunger feelings and satiety. It being reduced can lead to an increased appetite while at the same time just not being able to get satisfied. The next time you are burning the midnight oil and are ravenous the following day, remember that the lack of sleep is what did it to you.

In comes another player, Ghrelin. Ghrelin is responsible for hunger. If you have foregone sleep for a while your ghrelin levels are elevated. Higher levels of ghrelin are associated with higher levels of hunger. In combination with lower levels of Leptin you are in for a day of uncontrolled feasting.


A hormone that is connected to increased visceral body fat distribution (belly fat and organs) is an important stress hormone. We are usually exposed to higher levels in the morning and it tapers off throughout the day. Sleep deprivation will not increase the cortisol levels necessarily but reduces the peak in the morning and increases the exposure during the day, changing the normal hormone rhythm. This could lead to

  • decreased cognitive functions
  • decreased muscle tissues
  • decreased bone density
  • blood sugar disbalance
  • compromised immune system.


If you are trying to get stronger or gain some lean muscle mass, you need all the testosterone levels you can get [naturally]. Losing sleep can really reduce testosterone levels. There is no conclusive data on how much exactly but at the moment it is about 10-30%. This reduction happened within 24 hours of sleep reduction.


If you really want to be successful you cannot ignore sleep like it is something for pantsies. Quite the opposite, sleep is something for people who want to be successful. The effects described here are just a few. There are many more. If you want to kick some butt in any aspects of life, you cannot disregard sleep as an important factor.

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