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Is a Lack of Sleep Making you Fat?

Updated: Mar 15, 2023




So, is lack of sleep making you fat? - In short, the answer is YES!


I cannot recommend Matthew Walkers book 'Why we sleep' more highly. Although a neuroscience book, it's actually a very easy read and is rather funny in places. Drawing on 20 years of research, he explains how we can harness sleep to improve learning, mood and energy levels, regulate hormones, prevent cancer, Alzheimer's and diabetes, slow the effects of aging, and increase longevity. He also explains why a lack of sleep can cause us to get fat!


Lack of Sleep Increases Appetite


A lack of sleep affects our appetite by having a significant affect on the hormones leptin and ghrelin . Leptin is the hormone that creates the signal in our brain that we are feeling full. Ghrelin is the opposite and is the hunger hormone that increases our appetite and screams "EAT!!!!!'. If you are only getting 4-5 hours sleep a night then leptin decreases by 18% and ghrelin increases by 28%. A double whammy! So our brains are dulled in getting the 'I'm feeling full' signal, but rather is swamped with the 'I must eat and I must eat now!' signal. And if this isn't bad enough, his research shows that what our bodies desire in this state are obesogenic foods (creating excessive weight gain) - simple carbohydrates such as sugar and starch. It also drives us to reach out for salty snacks too which in turn leads to hypertension.


If you are only getting 4-5 hours sleep a night then leptin decreases by 18% and ghrelin increases by 28%. A double whammy! So our brains are dulled in getting the 'I'm feeling full' signal, but rather is swamped with the 'I must eat and I must eat now!' signal.

Now add to this that sleep deprivation causes the body to hold onto fat whilst metabolising muscle, which is protein. So, when you get insufficient sleep, you will most likely be losing muscle mass rather than body fat. Muscle is the engine room for calorie consumption. When we lose muscle we slow down our metabolism and therefore more of what we eat gets stored as fat, as our bodies simply are not needing it for fuel to burn.


So, when you get insufficient sleep, you will most likely be losing muscle mass rather than body fat. Muscle is the engine room for calorie consumption.

Bottom Line- Getting the Right Amount of Sleep is Essential for Health and Weight loss


Getting 7-9 hours of quality sleep is crucial for weight loss but also all other aspects of our health and wellbeing. Have a good look at your bedtime routine.


Tips to Create a Healthy Bedtime Routine


  1. Our bodies adapt with repetition so set a clear lights out time, say 10pm and then a regular wake up time, say 6am.

  2. An hour before bed consider dimming lights to start to release the bodies sleep hormone, melatonin.

  3. A warm bath also helps promote sleepiness before bed by tricking the body into preparing for sleep with the drop in body temperature once you get out.

  4. Writing in a journal to get the thoughts of the day out of your head and onto paper can put a stop to those racing thoughts at night.

  5. Whilst writing gratitudes in a journal generates positive, calm thoughts before sleep.

  6. There are also many fabulous mediation apps, such as Headspace or Calm, which can help create restful body and mind before bedtime.




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