Updated: Mar 30
Losing weight is a challenging process. However, maintaining the healthy bodyweight afterwards is even more challenging. Statistically, people who lose weight by following a diet regain all of the lost weight within a year. (US National Center for Chronic Disease Prevention and Health Promotion)
Gaining weight is partially related to appetite while it is mostly because of hormones regulating the body weight. Known as the “hunger hormone”, “ghrelin” plays a major role in gaining weight since it transmits signal to the brain to eat more. (University of Turin)
What is Ghrelin?
Ghrelin is a hormone that is produced by endocrine X(A) cells in the stomach. Although it is predominantly synthesized in the stomach, its presence has been found in many organs such as the intestines, heart, kidney, liver, lung, pancreas and placenta. It is generally called “hunger hormone”.
Ghrelin reaches the brain through the blood circulation after it is produced. It gives the message to the brain that the individual is hungry and should eat. The main function of this hormone is to boost appetite. It causes increased consumption of food, calorie intake and deposition of fat. (VU University Medical Center)
Ghrelin hormone also affects the sleep cycle, reward seeking behavior, sense of taste and carbohydrate metabolism. (University of Santiago de Compostela)
This hormone is produced when the stomach is empty. The higher ghrelin level is, the more hungry the individual feels. If ghrelin level is low, the individual feels full and takes less calories. Therefore, regulating ghrelin levels is a quite effective way to lose weight.
Why does it elevate?
Ghrelin levels generally elevate before meals and when the stomach is empty. It starts decreasing in a short time after the individual eats and the stomach is full. (University of Washington)
Although it is considered that ghrelin levels are higher for individuals with obesity, this is not correct. These individuals are more sensitive to the effects of this hormone. Some studies demonstrated that obese individuals have lower ghrelin levels comparing to slim individuals. (Eli Lilly and Company, Charles University, University of Witten-Herdecke)
Other studies discuss that the obese individuals can have an overactive ghrelin receptor known as GHS-R that causes increase in calorie intake. (Imperial College, VU University Medical Center)
Even if fat deposition in body is sufficient, when the individual starts following a diet, ghrelin levels elevate and the individual feels hungry. This is a natural response of the body to protect itself from hunger. Appetite increases during diet, which results in decrease in leptin hormone level which is known as “satiety hormone”. Especially if a low-carbohydrate is followed, metabolic rate significantly tends to decrease. (University of Lausanne, University of Washington)
Due to these reasons, practices like diet that require changes in nutrition make losing weight and not regaining the lost weight quite challenging. This is because the hormones and metabolism are reregulated by focusing on regaining all the lost weight.
How it is related to diet?
Ghrelin levels start to increase within a day after starting a diet. This change continues for weeks. In a study performed on human subjects, ghrelin levels have increased by 24% in a 6-month diet program. (University of Washington)
On a study performed on human subjects that follow 3-month diet to lose weight, researches have observed that ghrelin levels have increased from 770 to 1.322 pmol/liter, in other words, they have increased almost 2 folds. (Pennsylvania State University)
In another study performed on human subjects who follow a 6-month body building diet and have been exposed to serious nutritional restrictions, ghrelin levels have increased by 40%. (Fitchburg State University)
All these scientific data show that ghrelin level increases proportionally with the duration of diet and the amount of the lost fat and muscle mass. This makes maintaining body weight after weight loss challenging.
How to decrease ghrelin level?
It is known that ghrelin is a hormone that cannot be directly controlled with diets and supplements. Recommendations by specialists to help preserving ghrelin levels are listed as follows: