Introduction:
Appetite refers to the absence of fullness in the gastrointestinal tract with anticipation of the pleasure of eating or reward from food intake. Besides hormonal factors in the gastrointestinal tract, the hypothalamus, the brain, and the central control area are responsible for regulating appetite and are related to higher-order neural circuits in food reward. Hedonic hunger can increase the desire to eat, even in a physiological hunger absence.
What Is the Cause of Postoperative Appetite Loss?
Patients undergoing esophagectomy experience surgery as bodily distribution. They experience a loss of appetite for many weeks. It is like the pathway between the stomach and the brain is cut, which is included in psychological factors.
Ghrelin is a hormone produced in the fundic gland of the stomach and has an important role in appetite regulation and in appetite loss after gastrectomy. Ghrelin hormone level changes in gastric reconstruction and esophagectomy. This results in a reduction of ghrelin level in plasma level by 50 percent as compared to a reduction of 88% in total gastrectomy and 50% in two-thirds of distal gastrectomy, and there is no change in colectomy procedure.
These are the measurements taken three to seven days after surgery. In long-term follow-up, this hormone level is positively correlated with time from the operation, and it is higher than in the control group of preoperative cancer patients without prior weight loss three years after surgery. Koizumi et al. found that both appetite and ghrelin plasma levels decreased one month after esophagectomy, with both recovering one year postoperatively. Appetite and ghrelin plasma levels showed a strong positive correlation.
Satiety Hormones and Bowel Motility
Reduced ghrelin levels cause appetite loss, and also it is caused by an exaggeration of satiety hormones. Dehes-tani and le Roux reviewed the role of the small bowel in unintentional postoperative weight loss and described the rapid progress of food through the small bowel after upper gastrointestinal surgery as a cause that leads to the adaptation of small bowel mucosa and increased secretion of satiety gut hormones such as GLP-1 with a similar effect on satiety caused by bile entering the small bowel fastly.
A change in gut microbiota leads to faster satiation. Preserving the duodenal passage also results in more normal (rather than increased) levels of the appetite-suppressing hormone cholecystokinin. Reduced motility of the bowel is the other cause of loss of appetite. Tomita et al. found that the absence of interdigestive migrating motor complex phase three during fasting is highly correlated with loss of appetite after gastric surgery. Where interdigestive migrating motor complex phase three was present, they had almost no loss of appetite. Its absence is correlated with appetite loss. Tomita et al. found that prokinetic agents that stimulate gastrointestinal movements improve symptoms postoperatively.
How Is Appetite Loss Measured?
Appetite loss can be assessed by self-report, but it is prone to subjective distortion. A more common and precise method is VAS- Visual Analogue Scale, assessing appetite sensation in single-test meal studies.
What Is the Surgical Influence on Appetite Loss?
Following esophageal resection, patients experience a complete loss of appetite. In colorectal surgery, appetite loss is reported as mild. In patients with pancreaticoduodenectomy, for treating pancreatic adenocarcinoma, loss of appetite is mild. In various publications, they have reported the complexity of the influence of surgery on appetite loss.
What Are the Pharmacological Treatment Methods for Postoperative Appetite Loss?
Peripheral-acting antagonist, Alvimopan has a good influence on the functioning of the gastrointestinal system, but its effect on appetite is not yet revealed.5-hydroxytryptamine 4 (5-HT4)-receptor-agonist mosapride citrate has a non-significant trend on restoration on postoperative appetite after gastrectomy on distal. Cannabinoids and corticosteroids are appetite stimulants known as palliative drugs. For appetite hormone, ghrelin synthetic intravenous application improves appetite in the immediate postoperative period.
What Are the Non-pharmacological Treatment Methods for Postoperative Appetite Loss?
Gum chewing after colorectal surgery has no impact on appetite but also increases the incidence of bloating, indigestion, and eructation in the chewing gum group. Gum chewing daily done three times for one hour after sigmoid surgery shows a reduction in bowel movement and length of hospital stay. In a randomized controlled trial, gum was chewed three times a day from the first day till the day of discharge, the time to feeling hungry, the time to first flatus, and first bowel movement but no reduction in length of hospital stay.
In a randomized controlled trial of patients with laparotomy done for ileostomy closure after typhoid perforation peritonitis, gum chewed three times a day for one hour had a shorter time to return of hunger, first flatus, and first bowel movement than others. Randomized controlled trials in patients with laparoscopic colonic resection do not show any benefits of gum chewing. The introduction of Alvimopan into routine care midway through the trial led to the exclusion of numerous patients.
Nutritional supplements after pancreatic surgery are done to treat loss of appetite, and it is done with liquid supplements, eight to ten small meals per day, and low-calorie food. Appetite loss will reduce significantly after discharge from the hospital, a meta-analysis done in nine randomized controlled trials comparing home enteral nutrition with the oral diet after esophagectomy for esophagus cancer. This study reported less appetite loss after three months in patients with minimally invasive surgery with home enteral nutrition versus patients who had open esophagectomy, with no difference between these groups two weeks after discharge. Another random controlled trial is done to find the effect of oral nutritional supplements with dietary advice versus dietary advice alone for three months. This was done postoperatively in patients with gastric cancer, and it was found that oral nutritional supplements resulted in less appetite loss.
Conclusion:
Loss of appetite is an important problem following abdominal surgery, especially in esophageal and gastric surgery. The evidence regarding the treatment of appetite loss following lower abdominal surgery is limited. There are pharmacological and non-pharmacological approaches for controlling the loss of appetite after abdominal surgery.
