Sleep and weight gain are closely linked

Many studies have shown that people who sleep less, both in quantity and quality, tend to have higher body mass index (BMI) scores^{1, 2}. And if everyone has experienced increased appetite after a bad night’s sleep, this phenomenon now has a well-known explanation.

A matter of hormones

Lack of sleep influences many metabolic aspects, particularly four hormones involved in weight management. According to various experimental studies^{3, 4, 5}, even just a few days of sleep deprivation can lead to increased levels of insulin, cortisol, and ghrelin, as well as decreased levels of leptin. This translates into weight gain not only due to induced overeating but also due to the metabolic effects themselves.

• Ghrelin and leptin: the hunger and satiety duo

Ghrelin has an orexigenic effect. It’s a hormone produced and secreted by our stomach that largely regulates our physiological hunger. In the case of disrupted sleep, ghrelin will be produced in excess, pushing us to eat more, even without real hunger. Moreover, ghrelin tends to promote hedonic food intake, leading us unconsciously towards the most calorie-dense but not necessarily the most nutritious foods. At the same time, our leptin levels, a hormone produced by adipose cells that regulates our satiety, significantly decrease. It’s easy to understand then that food intake increases, independently of our will.

• Cortisol and insulin: from stress to weight gain

The increase in cortisol, the stress hormone, induced by lack of sleep tends to increase appetite, especially for sugary products. At the same time, it promotes the development of insulin resistance. Cells have insulin receptors that allow glucose to enter. In the case of insulin resistance, where these receptors fail to recognize insulin, insulin levels will increase significantly in response to this non-recognition. However, insulin is our storage hormone. The more we produce, the more fat we accumulate, especially around the abdomen and upper body. Conversely, the more stressed we are and the more fat we accumulate, the higher the risk of sleep disorders: insomnia, apnea, hypopnea, and agitation.

The vicious cycle of non-restorative sleep

As we’ve seen, poor sleep leads to detrimental eating habits that can cause weight gain. This weight gain can then lead to sleep disturbances such as snoring or even serious conditions like obstructive sleep apnea.

By Audrey Charial, nutritionist and micronutritionist.

1. Anne G Wheaton, Geraldine S Perry, Daniel P Chapman, Lela R McKnight-Eily, Letitia R Presley-Cantrell, Janet B Croft, Relationship between body mass index and perceived insufficient sleep among U.S. adults: an analysis of 2008. BMC Public Health, 2011, 11:295
2. Kim CW, Choi MK, Im HJ, Kim OH, Lee HJ, Song J, Kang JH, Park KH., Weekend catch-up sleep is associated with decreased risk of being overweight among fifth-grade students with short sleep duration. J Sleep Res. 2012 Oct;21(5):546-51. doi: 10.1111/j.1365-2869.2012.01013.x. Epub 2012 Apr 12
3. SpiegelK., TasaliE., PenevP. & Van Cauter, E. Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med 2004;141: 846-850.
4. Spiegel K., et al. Leptin levels are dependent on sleep duration: relationships with sympathovagal balance, carbohydrate regulation, cortisol, and thyrotropin. The Journal of clinical endocrinology and metabolism 2004; 89: 5762- 5771.
5. Spiegel K., Tasali E., Leproult R. & Van Cauter, E. Effects of poor and short sleep on glucose metabolism and obesity risk. Nature reviews 2009; 5: 253-261.