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 weight loss injections, 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 in weight regulation: 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, glycogen synthesis and GLUT4 uptake while inhibiting lipolysis and stimulating fat storage through PI3K-AKT and mTOR signaling.
- Glucagon from pancreatic alpha cells works in the opposite direction, driving hepatic gluconeogenesis and lipolysis through the cAMP-PKA pathway.
- Growth hormone from the anterior pituitary inhibits lipogenesis, stimulates lipolysis and fatty acid oxidation, and promotes myofibrillar protein synthesis via JAK-STAT and mTOR.
- Cortisol from the adrenal cortex mobilizes amino acids through skeletal muscle proteolysis and drives central fat redistribution, acting through MuRF1 and Atrogin-1 expression.
- In a deficit insulin falls while ghrelin rises and leptin falls, and GLP-1 agonists work upstream of all five hormones by slowing gastric emptying, potentiating glucose-dependent insulin secretion, and suppressing glucagon.
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 Abilene, 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 |
