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Hunger Hormones Ghrelin & Leptin After Bariatric Surgery

January 29, 2020

How many diets have you been on? How many times have you read the weight loss diet list, cleaned out the pantry, purchased all the foods, followed the recipes, and lost the weight? How many times have you gained it back? Part of the reason this occurs is due to two hunger hormones, Ghrelin and Leptin.

Ghrelin is often called the hunger hormone because it increases appetite. Leptin is known as the satiety hormone because it tells the brain when we’ve had enough. Both of these hunger hormones work to maintain our weight.

Hunger Hormones - The Ghrelin Hormone

Ghrelin is a hormone produced in our stomach – primarily in the fundus - that acts to increase appetite and stimulate growth hormone. Ghrelin levels rise just before a meal and drop after eating. Ghrelin also stimulates the release of food out of the stomach and into the intestines.

In individuals with obesity, ghrelin levels are reduced. At first thought this is confusing: If ghrelin stimulates appetite and I’m eating large portions or eating all day, then shouldn’t my levels be elevated to continually stimulate my appetite?

The lower levels of ghrelin in people with obesity may be part of the cause of increased food intake. This lower baseline level and lack of significant shifts in ghrelin levels before and after meals may explain grazing habits in those with obesity.

If there is no significant increase in appetite before eating or a significant feeling of satiety after eating, a person is more likely to graze on small meals and snacks throughout the day, possibly leading to excess calorie intake. Without the significant decrease in ghrelin levels after a meal, the inclination to eat may last longer, and thus larger portions are consumed.

Hunger Hormones - The Leptin Hormone

Leptin is a hormone released from fat cells and thought to be “the most influential in terms of appetite regulation and energy stores.”[1]  Leptin regulates food intake and energy expenditure over the long term (instead of a meal by meal like ghrelin), in an effort to maintain weight. Leptin tells our body we’re full and satiated.

In general, as we lose weight, leptin levels reduce, which causes increased appetite and increases food intake; as we gain fat,  leptin levels increase. In someone with obesity, there will be an excess of leptin in the blood, causing decreased sensitivity to the hormone or leptin resistance.

After a reduced-calorie diet, levels of ghrelin increase, which increases hunger and making it difficult to maintain a new diet and new body weight. With weight loss, leptin levels decrease, which can further trigger increased appetite as the body tries to return to its original weight.

This is especially difficult after rapid weight loss often seen in very-low-calorie diets, keto diets, and Atkin’s style diets when the change in diet and weight is drastic and quick. This is why, no matter how trendy or which celebrity is promoting it, most diets fail to result in sustained weight loss or maintenance of that goal weight.

Gastric Bypass and Gastric Sleeve Affect Ghrelin Levels Differently

Gastric bypass and gastric sleeve affect ghrelin levels differently than diet alone. After either procedure, ghrelin levels actually decrease, which may be one of the reasons surgery is more effective long term than diet alone. With the gastric sleeve, the fundus of the stomach is removed. Most of the ghrelin is produced in the fundus of the stomach so ghrelin levels drop significantly after gastric sleeve. Leptin levels are reduced after gastric bypass and sleeve gastrectomy as soon as one week after surgery and continue to drop with a reduction in body fat.

Some studies cite significantly reduced appetites following sleeve gastrectomy even two years after surgery. One study found decreased ghrelin after six months but an increase in levels at 12 months post-op [2]. With significant changes in hunger hormones initially after surgery, patients find weight loss and appetite control to be much easier than prior to surgery and see successfully sustained weight loss. The fundus of the stomach may be the main site of ghrelin production, but it is not the only one. Ghrelin is also produced in the small intestine, and some are released in the pancreas and the brain.

While weight loss and appetite control seems easy for the first 12 months after surgery there may be a later increase in ghrelin near that 1 year mark explaining the slight weight regain regularly seen around this time.

To ensure you maintain your new weight, schedule an appointment with a bariatric dietitian around the 9-12 month mark after surgery. She or he can help you evaluate your eating patterns and food choices and provide guidance and accountability as the ‘magic’ of surgery wears off.

When the hormone levels and appetite begin to change around a year after surgery, patients should take advantage of their bariatric clinic and staff by attending support groups and follow-up appointments to help remain successful after their procedure.

The surgeons and dietitians involved in your weight loss journey want to help ensure you reach and maintain your success and obtain a healthy lifestyle. If you’ve had a gastric bypass or gastric sleeve and are struggling with weight regain, please reach out to your bariatric clinic. They are there not to judge you - but to help you out EVERY single step of the way.


  1. Neurohormonal Effects on Obesity  Nov 1, 2017, April Smith Pharm D MA BCPS
  2. Dietary intake and ghrelin and leptin changes after sleeve gastrectomy. Videosurgery Miniinv 2014; 9 (4) 554-561
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Jeannie Boyer


Jeannie Boyer is a registered dietitian, licensed in South Carolina with over 10 years of experience with weight loss and weight management along with a background in clinical nutrition. She obtained her B.S. in nutrition from East Tennessee State University followed by a dietetic internship at Emory Hospital in Atlanta, GA. Jeannie spent many years working with a bariatric practice in California before moving back to the south and is excited to continue working with weight management at East Cooper Bariatric Surgery.