What is ghrelin and how does it work?
Ghrelin is an amino acid produced by stomach, especially by the wide upper side of it called fundus. It is also released from the first part of small bowel or duodenum. This amino acid is orexigenic, that means it is a hormone stimulating appetite.
When ghrelin levels increase, signals leading to eating go to brain. Change in ghrelin levels has been seen in many obese people. This makes those people to feel they need more food than they really need.
Levels of this hormone go up before the food intake and this amount decrease with some calorie intake. Ghrelin levels rise in dieting people. This explains why it is so hard to achieve long-term weight loss. On the other hand, the decrease required to be seen after the meals is lower in obese people compared to normal weight ones. That leads the appetite to continue or come back even after enough food consumption.
How does ghrelin affect weight gain?
Ghrelin is released during negative energy balance situations such as empty stomach, low-calorie diet, and anorexia nervosa. This partly explains why people feel that hungry when they are on a diet. Ghrelin concentration rises before meals, stimulates appetite and decreases after food consumption.
How does sleeve gastrectomy affect ghrelin production and level?
Most bariatric surgeries restrict the food amount that a patient can take in one go. Sleeve gastrectomy includes the total removal of fundus, which is the most important part to produce ghrelin, and takes ghrelin levels down. It has been shown that fundus includes 10-20 times more ghrelin for 1 gram of tissue compared to duodenum.
What happens to hunger hormone ghrelin after sleeve gastrectomy?
Contrary to vertical banded gastroplasty, gastric plication or gastric balloon, in sleeve gastrectomy stomach capacity reduces almost 80% and patients do not only eat less but they feel fuller between the meals and experience less appetite attacks. With the combination of these two, it is possible to reach ideal weight losing permanent and serious weight loss. In other words, patients of sleeve gastrectomy feel less appetite and feel of fullness come earlier and lasts longer.
It has been indicated that blood ghrelin levels reduce significantly in patients after sleeve gastrectomy. This fall starts with the first day of operation and continues more than 24 months. In other operations like stapling, it rises before this. This explains minimum 60% weight loss in 6-18 months after sleeve gastrectomy. This rate is 20-50% in stomach stapling.
Ghrelin and Gastric Bypass
There are some publications on this. While some studies record meaningful fall in ghrelin levels after gastric bypass, other studies claim that there is no significant change in this because fundus is not resected.
What do patients experience about appetite after sleeve gastrectomy?
Per the experience, we have collected from our patients, which is more important than studies, patients observe a significant difference in hunger level and concentration after sleeve gastrectomy. Some patients tell that they did not feel hunger for months and had to set alarm to remember meals. This is a very big change for someone feeling hungry all the time.
On the other side, psychological hunger drive may be more stubborn than the physical one. Even so, choosing more right food and being more controlled in eating is possible. Feeling of fullness improves as patients switch to solid food. In this term, eating much leads to unwanted results, such as ache, sickness, and vomiting.
In this 18 months’ process, if patients, who cannot change eating habits of years and mental and emotional attitudes, could not use the biggest chance they obtained, there will be a probability of gaining weight back. None of the methods in obesity surgery is strong enough to achieve permanent weight loss in spite of the malfeasances of the patients. It should not be forgotten that bariatric surgery is not just a physical change; fighting against mental and emotional eating and acquiring healthy eating habits are also important in long term success.
Other Features of Ghrelin Still under Research
Some other hormones have a role in the fall of the ghrelin levels after sleeve gastrectomy. Some like leptin helps formation of feeling of fullness, reduce appetite and control blood sugar. All the mechanisms behind the success of sleeve gastrectomy in weight loss have not been fully explained. However, it is for sure that this surgery is not just a restrictive method, but it creates some metabolic changes, too.
Moreover, ghrelin is a kind of supportive or alternative endocrinological regulator, which provides diabetic remission in connection with insulin release, insulin resistance, obesity and metabolical syndrome. Simply, ghrelin does nıt only oppress appetite it can also be said to perform very effectively in control of the metabolical diseases.
The impact of ghrelin in the success of obesity surgery and sleeve gastrectomy is still being researched. The presence of many other bowel hormones has been determined as being the key in appetite control. What is for sure is, as the effect is obvious on the regulation of diabetes, success is multiway, which cannot be restricted only with limiting or emission disruption.
It has been proved that ghrelin is not only effective in blood sugar metabolism but also in stress oppression and increasing the duration and quality of sleep.
Lastly, let me remind you that total fundus removal is very important but it is impossible to destroy ghrelin wholly, because appetite is a necessary and natural feeling after normalization of degenerated mechanisms and ghrelin is a necessary hormone in low levels. Now you know that you should approach skeptically to the doctors or clinics claiming that they make ghrelin disappear completely. I wish everyone a day with low ghrelin.