Why does surgical removal of part the stomach decrease appetite?

There are a few reasons why surgical removal of part of the stomach (gastrectomy) can lead to decreased appetite:

1. Reduced stomach volume: After gastrectomy, the size of the stomach is reduced, which means it can hold less food. This physical restriction can lead to a feeling of fullness and satisfaction after eating smaller amounts of food, resulting in decreased appetite.

2. Hormonal changes: Ghrelin is a hormone produced by the stomach that stimulates appetite. After gastrectomy, the production of ghrelin may be reduced, which can contribute to decreased appetite. On the other hand, the levels of other hormones that suppress appetite, such as cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1), may increase after gastrectomy, further reducing the desire to eat.

3. Alterations in gut-brain signaling: The gut and the brain communicate through various mechanisms, including the vagus nerve. Ghrelin and other gut hormones act on the vagus nerve to stimulate hunger and appetite. After gastrectomy, the vagus nerve may be damaged or altered, disrupting the normal signaling between the gut and the brain, which can lead to decreased appetite.

4. Malabsorption and nutrient deficiencies: Gastectomy can also affect the absorption of nutrients, as the stomach plays a crucial role in the initial stages of digestion. This can lead to deficiencies in certain vitamins, minerals, and nutrients, which in turn can contribute to fatigue, weakness, and decreased appetite.

It's important to note that the specific impact of gastrectomy on appetite can vary among individuals and depends on various factors such as the extent of stomach removal, the type of surgical procedure, and individual responses to the surgery.