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Sleep and Weight: The Secret Connection

Sleep and Weight: The Secret Connection


We all have experienced days when we have had too little sleep, say only 3-4 hours, and have felt tired throughout the next day. Is lack of sleep affecting our health in more ways than one? What happens if we sleep more or less than the recommended amount? Is there any difference between sleeping for three hours vs sleeping for eight? Is there a connection between weight and sleep?  

The answer to all these questions is simple. There is a connection between our sleep patterns and our well-being. The number of hours we sleep affects how well our body functions.

People that are sleep deprived are at high risk of developing obesity, in addition to a host of mental and physical health issues like heart diseases, stroke, stress and exhaustion. Research has also shown that people who get sufficient sleep have lower health issues in the long run.

Let’s first explore our body’s internal clock.

Sleep and Our Body’s Internal Clock
When it comes to sleep, we cannot overlook the body’s internal clock – Circadian rhythm or cycle. It is an internal 24-hour clock that responds to light changes in the environment and manages your alertness and sleepiness.

Our internal body clock controls one such cycle: the sleep-wake cycle. During the day, the light signals our brain and generates alertness, whereas, at night, the brain initiates melatonin (hormone) production and promotes sleep. Certain factors like Jet Lag and Shift Work can disturb this cycle and affect your sleep.

Why is Good Sleep Essential for Weight Loss?
A good night’s sleep is just as essential as diet and exercise for weight loss. People with obesity look for several weight loss treatments and may often overlook other factors that also play a role. From all those factors, hours of sleep is a crucial one. There is no fixed amount of sleep hours for everyone, and it depends on our bodies.

However, sleeping for 7-8 hours every night keeps our bodies in rhythm. The body gets proper rest, and all hormones and organs work well. In addition, good sleep also boosts our metabolism that in turn helps in obesity control.

The Science Behind Sleep, Appetite Hormones and Obesity

It is well documented that people who sleep for fewer hours experience significant weight gain.

Sleep deprivation primarily affects our brain and our appetite-related hormones. As a result, we tend to eat more than our body requires. It happens because of the imbalance in hormones that control hunger and “fullness”. These two are our appetite hormones. The first one is Ghrelin, also known as the hunger hormone – which signals us to eat. The other one is Leptin – the satiety hormone, which asks us to stop eating when we are full.

Scientists have seen that people that slept for less than 5 to 6 hours had an imbalance in these two hormones. People deprived of sleep have increased hunger hormone and reduced fullness hormone in their bodies. Another scientific study has also shown that people who sleep less than seven hours per day tend to eat 300 more calories per day than people who get enough sleep.

In addition, when our brain is over exhausted, it looks for things that make it happy, like food. This is because it is drawn to foods with higher levels of saturated fat, like fast food, cheese and processed meats. Over time, these become foods that cause weight gain.

In Summary
Sleep has a huge impact on our health and quality of life. We need between seven and nine hours of sound sleep every night for our body and brain to rest and recover. Sleep any less than that, and our ability to concentrate may suffer and our immune system may weaken. Moreover, as our appetite hormones become imbalanced, we end up eating more food – and often more unhealthy food – than we need to and experience weight gain.

Simple Steps for Better Sleep
Good sleeping habits can help us to make healthy choices and improve our ability to resist tempting foods. Relaxation techniques and behaviour therapy may help you as they have a positive effect on sleep. In addition, incorporating a few simple habits such as below can also help you fall asleep faster and get more restful sleep.

  • Not drinking alcohol, coffee or tea and avoiding other stimulants four to six hours before sleeping.
  • Avoid smoking before bedtime or during the night.
  • Avoid heavy meals and spicy foods before going to bed.
  • Getting more physical exercise during the day, but avoiding exercise right before going to bed.
  • Trying to make sure your bedroom is quiet, dark and not too hot or cold.

Remember, sleep directly affects your well-being and has an impact on the management of obesity. If you experience symptoms of obesity, consult a specialist.

Conventional therapies such as lifestyle modification (diet and exercise), medication, and various bariatric treatment options are available to help reduce weight. However, it is best to seek the advice of an obesity specialist. They might suggest some exercise for weight loss and a diet for obesity. Speak to a weight loss surgeon to understand how you can manage your weight better.


  • Hirshkowitz M et al, National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health. 2015 Mar;1(1):40-43.
  • Taheri S, Lin L et al, short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. PLoS Med. 2004 Dec;1(3): e62.
  • Reddy S et al, Physiology, Circadian Rhythm. 2021 May 9. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan
  • Brasure M et al, Management of Insomnia Disorder [Internet]. Rockville (MD), 2015 Dec. Report No.: 15(16)-EHC027-EF
  • St-Onge MP et al, short sleep duration increases energy intakes but does not change energy expenditure in normal-weight individuals. Am J Clin Nutr. 2011 Aug;94(2):410-6.

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