Sleep and obesity
Impact of sleep deprivation on weight gain
In French it is said “qui dors, dîne” – who sleeps, have dinner. It could be the typical cliché, but as often happens, it is in the popular wisdom where we find the truth.
Have you ever heard of ghrelin and leptin? Most likely not, yet they are directly responsible for your feeling of hunger or satiety.
The ghrelin (an acronym composed of Groth hormone relasing- which induces an increase in growth hormone) is a hormone produced mainly by the cells of the stomach’s fundus. Its function is substantially oressizing. That is, it causes hunger. Clinical studies have shown an increase in bulimia patients and a sharp decrease in disorders of anorexing behavior.1
Its opposite is leptin (from the Greek leptòs: slender), a hormone produced principally by fat cells that sends messages to the brain of satiety.
A study carried out at Stanford University, has shown with rather solid data, a relationship between sleep, ghrelin and leptin.
1024 volunteer people with sleep disorders were enrolled. Their sleep was studied through a polysomnography (that is, through the electrodes a monitoring of the quality and quantity of sleep is performed).
On the following day, ghrelin, leptin, insulin and other metabolic hormones were dosed.
Data analysis showed that patients who slept less than 8 hours had high ghrelin and low leptin levels. This predisposition to be more hungry was also witnessed by a higher BMI (body mass index).
The chronic deprivation of sleep and the high availability of food in our western society, induce major changes in the concentrations of hormones regulating appetite. Both contribute consistently to obesity.2
How to reverse this trend? The ghrelin sends messages to the brain through the vagus nerve. When a situation of deprivation and fasting occurs, the levels of ghrelin increase and the message is conducted to the “higher levels” through another peptide called Y (NPY) the message arrives in the arcuate nucleus of the pituitary gland3. When I picture the pituitary (or pituitary gland) I imagine it as the control panel of the Millenium Falcon. From here all our hormonal messengers depart. Each button (= cell) promotes or inhibits hormone secretion through a feed-back mechanism.
When we sleep sufficiently, or about 8 hours, the levels of leptin (or the satiety hormone) increase, hence the veracity of the known French proverb.
When I was a new mother and spent the nights waking up to nurse and I was not able to go back to sleep, the next day I was often tired and sleep deprivation led me to eat more often and with a higher energy density (i.e. chocolate) for to be able to resist another tiring day in which I could hardly recover. And so that I lost the kilos taken in pregnancy only when my children began to sleep: Coincidence? I do not think so.
A separate note deserves the relationship between bariatric surgery and ghrelin. As demonstrated in the work of Dr. Sista (which I have the privilege of knowing) and of Dr. Carandina (which I was fortunate enough to marry!), Bariatric surgery decreases ghrelin levels through the direct removal of the part of the stomach that most produces it: the fundus. Levels remain low for about 5 years after surgery4. In cases of weight regain it could be hypothesized that the remaining stomach has acquired the capacity to produce ghrelin again or that additional production sites have increased.
So here is an important difference to understand the yoyo effect of low-calorie diets. When we follow a strict diet and do not eat sufficiently, ghrelin levels will increase and will induce a state of irritability and frustration in the individual with an atavistic hunger.5 After a bariatric surgery this does not happen. In the case of a sleeve, the producer cells are directly eliminated, in the case of the by-pass, the lack of contact of the food with the producing cells, would induce an absence of the signal. 6
So, to conclude, we carefully take care of our sleep and we will probably manage better hunger and satiety. A good sleep is equivalent to a good dinner, but beware of the article mentioned 2 does not say to laze all day. The body needs to build sleep during the day: working, walking, doing sports, eating, laughing and crying, in other words -LIVING.
- Weight gain decreases elevated plasma ghrelin concentrations of patients with anorexia nervosa. Otto B et al. European Journal of endocrinology; Nov 2001 eje.bioscientifica.com
- Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. Taheri S et al. PLoS Med.Dec 2004
- Structure, regulation and function of ghrelin .Takahiro Sato et al. The Journal of Biochemistry, Feb2012, doi.org
- Effect of resected gastric volume on ghrelin et GLP-1 plasma level-Prospective Study. Sista et al. Journal gastrointestinal surgery, Sep 2016 researchgate.net
- Plasma Ghrelin Levels after Diet-Induced Weight Loss or Gastric Bypass Surgery. Cummings DE et al. New England Journal of Medecin, May 2002 ncbi.nlm.nih.gov
- Weight regain after gastric Bypass:influence of gut hormones. Santo A et al. Obesity Surgery , Oct 2015 researchgate.net