Which hormones control weight loss?
Five hormones do the heavy lifting: insulin (the storage switch), glucagon (the release switch), growth hormone (the fat-mobilizer), cortisol (the stress brake), and leptin (the fullness signal). The table below maps each one — where it's produced, what it does to carbohydrate, fat, and protein metabolism, and how it behaves during a caloric deficit. If you are here looking into medically supervised weight loss ft, the sections below walk through the process from the first quote to the finished job.
Why do GLP-1 medications change the hormone game?
GLP-1 receptor agonists work upstream of all five: they slow gastric emptying, potentiate glucose-dependent insulin secretion, and suppress glucagon — flattening the insulin spikes that drive fat storage. That's why the medications work even in patients whose diets are already reasonable: they fix the hormonal environment, not just the behavior.
The short version
- Five hormones do the heavy lifting: insulin as the storage switch, glucagon as the release switch, growth hormone as the fat mobilizer, cortisol as the stress brake, and leptin as the fullness signal.
- Insulin, secreted by pancreatic beta cells, upregulates glycolysis and GLUT4 glucose uptake, inhibits lipolysis, and drives myofibrillar protein synthesis via PI3K-AKT and mTOR.
- Glucagon, secreted by pancreatic alpha cells, upregulates hepatic gluconeogenesis and stimulates lipolysis and ketogenesis through the cAMP-PKA pathway.
- Growth hormone from the anterior pituitary inhibits lipogenesis and stimulates lipolysis while promoting myofibrillar protein synthesis through JAK-STAT and mTOR.
- Cortisol from the adrenal cortex mobilizes amino acids via muscle proteolysis through the ubiquitin-proteasome pathway and the glucocorticoid receptor NR3C1.
- In a deficit insulin falls while ghrelin rises and leptin falls, and GLP-1 therapy blunts that compensatory hunger signal so appetite stays manageable.
What happens to these hormones during weight loss?
In a deficit, insulin falls (good), but ghrelin rises and leptin falls (bad) — the body fighting to defend its set point. GLP-1 therapy blunts that compensatory hunger signal, which is why appetite stays manageable at a deficit that would otherwise be unsustainable. In Fort Myers, providers use this hormone profile to pick the right medication and dose for each patient.
The Data Table
| Hormone | Primary Secretion Gland/Tissue | Effect on Carbohydrate Metabolism | Effect on Lipid (Fat) Metabolism | Effect on Protein Metabolism | Receptor / Cellular Pathway Triggered | Source |
|---|---|---|---|---|---|---|
| Insulin | Pancreas (Beta Cells) | Upregulates glycolysis, glycogen synthesis, and GLUT4 glucose uptake; inhibits hepatic gluconeogenesis; increases insulin sensitivity | Inhibits lipolysis and hepatic ketogenesis; stimulates lipogenesis, triglyceride storage, and fatty acid synthesis | Stimulates amino acid uptake, inhibits proteolysis, and drives myofibrillar protein synthesis (MPS) | PI3K-AKT; mTOR signaling | 1, Inferred, 2, 3, 4, 5, User Description, User Narrative Description, 6 |
| Glucagon | Pancreas (Alpha Cells) | Upregulates hepatic gluconeogenesis and glycogenolysis; inhibits hepatic glycolysis and glycogen synthesis | Stimulates lipolysis, fatty acid beta-oxidation, and hepatic ketogenesis; inhibits lipogenesis | Limited role in protein metabolism | cAMP-PKA pathway | 1, Inferred, 2, 3, 4, User Description, User Narrative Description |
| Growth Hormone (GH) | Anterior Pituitary (Pituitary Gland) | Stimulates hepatic gluconeogenesis; reduces peripheral glucose uptake; decreases insulin sensitivity | Inhibits lipogenesis; stimulates lipolysis and fatty acid beta-oxidation | Promotes myofibrillar protein synthesis (MPS); inhibits proteolysis (muscle); synergistic with IGF-I | GHR; JAK-STAT pathway; mTOR | Inferred, 2, 3, User Description, 7, 6, User Narrative Description, 8, 1, 9 |
| Cortisol | Adrenal Cortex (Adrenal Gland) | Stimulates hepatic gluconeogenesis; reduces peripheral glucose uptake; decreases insulin sensitivity | Mobilizes fatty acids (lipolysis); stimulates fat redistribution (central/visceral) | Mobilizes amino acids via skeletal muscle proteolysis; reduces MPS; activates ubiquitin-proteasome pathway | Glucocorticoid receptor (NR3C1); MuRF1 and Atrogin-1 expression | 2, User Description, User Narrative Description, 8, 1, Inferred, 3, 4, 5 |
| Leptin | Adipose Tissue | Inhibits hepatic gluconeogenesis; increases insulin sensitivity | Minor stimulator of lipolysis; increases fatty acid oxidation; reduces lipogenic pathways | Inhibits muscle proteolysis | JAK-STAT pathway; PI3K; AMPK; Hypothalamic arcuate nucleus (SNS stimulation) | Inferred, 2, 3, User Description, 5, 7, 8, 1 |
