To maintain body weight, you must maintain an energy balance: energy intake has to be equal to energy expenditure. Your body has two hormones that regulate food intake and body weight. These are leptin and the “hunger hormone”, ghrelin.
Ghrelin is the hunger hormone while leptin stops appetite. Ghrelin stimulates the brain, which leads to:
- An increase in appetite,
- Slow metabolism, and,
- Decrease in the body’s ability to burn fat.
If you are obese, your leptin and ghrelin systems are disturbed. Many believe the actions of these “go and stop” appetite hormones are straightforward, and that one is good and the other is bad.
How ghrelin regulates hunger
Ghrelin was originally isolated from the stomach. But certain parts of your body may also produce this hormone. These include:
- Gastrointestinal tract,
- Ovary, and
- The adrenal cortex.
Normally, when you are hungry, ghrelin levels will go up dramatically and go down for about 3 hours after you eat. Additionally, if you are sleep deprived, your body will experience an increase in ghrelin levels.
Throughout the course of the day, ghrelin levels in your body will change dramatically and will increase before meals and decrease after meals. In addition to hunger, the following factors will affect how much ghrelin you secrete:
- Glucose, and,
- Insulin levels.
When your stomach is full and stretching, and if you are getting enough sleep, ghrelin secretion stops. More so, when you eat a diet high in protein, levels of the hunger hormone will be suppressed more effectively than if your diet is high in fat and carbohydrates.
How the hormone Leptin affects ghrelin levels
Your fat cells (adipose tissue) release leptin into the circulatory system. Leptin tells your body when you have had enough food. It also signals your brain that your body has enough energy, including body fat stores. If you eat fatty meals, this system doesn’t work as well.
If you go through a period of overeating, you will develop leptin resistance, whereby your hypothalamus is exposed to high leptin levels, resulting in altered leptin sensitivity.
It is now established that obese patients are leptin resistant. It is unknown if the abnormality of the leptin and ghrelin levels are the cause or a consequence of obesity. It’s worth noting that genetic conditions such as the Prader–Willi syndrome can increase ghrelin levels, resulting in obesity in children due to uncontrollable eating.
What can you do about the hunger hormone?
Altering ghrelin without surgery is something that researchers plan to discover for the future. Currently, there is no medication that has been shown to alter its levels effectively.
Although other obesity medications have been tried on patients, at the moment, none of these medications are free of side effects. More importantly, none are as effective as bariatric surgery. Typically, obesity drugs cause an average weight loss of 5–15% when combined with diet and exercise. On the other hand, bariatric surgery results in losses up to 30%.” 1
Gastric bypass creates a small gastric pouch and bypasses the duodenum. As a Gastric bypass patient, you exhibit different plasma ghrelin profiles. After gastric bypass, you will experience lower pre-meal increases in plasma ghrelin as compared to somebody who has not had surgery. Ghrelin levels are also reduced following sleeve gastrectomy.