Bariatric surgery is the most effective way to achieve significant weight loss and improve health for those with obesity and related issues like diabetes. Patients achieve control over the amount of food intake and, more importantly, experience hormonal changes that regulate hunger, insulin, metabolism, and weight.

Most patients see a stabilization in hormone levels within 6 to 12 months after sleeve gastrectomy and RNY gastric bypass.

Identifying participating hormones is the key to understanding the underlying mechanisms for dropping excess weight loss and the resolution of comorbidities. This essay will discuss the positive and negative hormonal changes after weight loss surgery and how to manage them.

What are Hormones?

Hormones are chemical messengers introduced into the bloodstream by the gland system (endocrine system). The pancreas, hypothalamus, stomach, fat cells, and other glands produce ghrelin, leptin, glucagon, insulin, adiponectin, sex hormones, and growth hormones. They regulate processes in the body, such as appetite, metabolism, and body fat distribution.

Exploring hormonal changes is pivotal to understanding weight loss after bariatric surgery.

Gastrointestinal (Incretin) Hormones

  • Ghrelin, known as the “hunger hormone,” was discovered in 1999. It signals the brain to eat when the stomach is empty.
  • CCK (Cholecystokinin) is responsible for stimulating the digestion of fat and protein.
  • GLP-1 (Glucagon-like peptide-1) helps the body release more insulin after meals to keep blood glucose levels balanced.
  • GIP (Glucose-dependent insulinotropic polypeptide) stimulates insulin secretion.
  • PYY (Peptide YY) acts in the hypothalamus to suppress appetite.

Insulin and Blood Sugar

  • Amylin inhibits food intake, delays gastric emptying, and decreases blood glucose levels.
  • Incretin hormones, or gut peptides, are released after eating and help increase insulin secretion along with high blood sugar.

Fat Hormones (Adipokines)

  • Leptin controls hunger and energy use.
  • Adiponectin helps with insulin sensitivity and inflammation.

Endocrine implications of bariatric surgery

Bariatric surgery influences the brain’s response to appetite stimuli and the interaction between brain and gut hormones. Resetting the metabolic system, inducing weight loss, and reducing body fat significantly impacts hormone production.

Hormonal Changes After Bariatric Surgery

Weight loss surgery restores ‘lean-type’ hunger, curbs cravings, increases PYY, and lowers appetite. GLP-1 rises, enhancing fullness and blood sugar control, leading to smaller meals and prolonged satiety. Additionally, CCK increases, boosting metabolism. Post-surgery, insulin function improves, blood sugar levels are lowered, and diabetes patients benefit. Fat hormones also shift: leptin decreases, but sensitivity to leptin increases, aiding in weight loss; adiponectin increases, reducing inflammation and enhancing metabolism.

Hormonal Changes ComparisonGastric SleeveGastric Bypass
Sensitivity to Leptin

Changes in Sex Hormones After Bariatric Surgery

Sex Hormone Changes After Bariatric Surgery Male Vs Female

In a scientific study involving 174 women, half underwent bariatric surgery while the other half formed a control group to observe any changes in hormone levels. They found that the mean average of the bariatric group after three months was 10.4 for FSH (helps ovaries produce eggs) vs. 8.1, and LH (triggers ovulation) was 6.2 vs. 5.3. The results of this study suggest that bariatric surgery can improve fertility (NIH).

  • Changes in estrogen and testosterone can improve fertility and hormonal balance.
  • Improvements in sex and fertility, particularly in women with PCOS.
  • Improves hormonal balance, sexual functions, and sperm count in men.

What is the impact of these hormonal changes?

The hormonal changes caused by bariatric surgery have several positive effects on the body. These include a smaller stomach and altered food digestion, leading to modified signals between the gut and brain. Reducing body fat improves overall health by decreasing the risk of obesity-related conditions such as heart disease, sleep apnea, and joint problems. Additionally, the surgery affects gut bacteria and microbiome, influencing metabolism and inflammation.

Hormonal Changes After Weight Loss Surgery -Mexico Bariatric Center

Health Benefits

Here are some positive effects of the hormonal changes after surgery:

  • Better blood sugar control and less need for diabetes meds
  • Long-term decrease in hunger
  • Improved cholesterol and lower heart disease risk
  • Better hormone levels can improve fertility
  • The hormonal changes after bariatric surgery can improve insulin sensitivity, reduce insulin resistance, and improve glucose control
  • Reduce the risk of developing type 2 diabetes and other metabolic disorders
  • A decrease in cortisol levels after surgery can reduce stress and improve mood

However, hormone changes can also have potential negative effects:

  • Macro and micronutrient deficiency due to reduced absorption
  • Osteoporosis or a decrease in bone strength
  • Hypoglycemia (low blood sugar)
  • Hair loss and excess skin
  • Changes in taste buds

Management of hormonal changes

Here are some helpful tips to manage your hormonal changes:

  1. Follow the post-op diet and exercise regularly.
  2. Attend follow-up appointments with your primary care doctor and have them check on your blood levels to avoid nutrient deficiencies.
  3. Drink plenty of water 64oz daily.
  4. Consume enough protein 75g-105g daily.
  5. Manage stress
  6. Be patient


Bariatric surgery increases incretin or gut hormones naturally, leading to substantial weight loss and better vitals for obese patients. These metabolic and hormonal changes reduce hunger, enhance metabolism, and improve insulin sensitivity, which can lower the risk of diabetes and heart disease.

Get this life-changing procedure with the most trusted U.S.-based company with the most experienced surgical teams, Mexico Bariatric Center®.

While positive effects include better blood sugar control, reduced inflammation, and improved fertility, potential downsides like nutrient deficiencies and decreased bone strength require supplement management. Overall, the hormonal adjustments following bariatric surgery are the key to its success.

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