# Common Questions About These Four Peptides > FAQ: Research Peptide Fundamentals — API Peptide — Answers to common questions about semaglutide, tirzepatide, tesamorelin, and BPC-157 — mechanism, approval status, and what the published research actually shows. **FAQ** Straight, cited answers about what each compound is, how it works, and what is and is not approved. ## What is semaglutide? Semaglutide is a synthetic 31-amino-acid peptide engineered to mimic and outlast the human hormone GLP-1. It is FDA-approved for type 2 diabetes, chronic weight management, cardiovascular risk reduction, and (since 2025) MASH, a liver condition [4]. ## What is semaglutide used for? Its approved uses are type 2 diabetes management, chronic weight management in adults with obesity or overweight, reducing major cardiovascular events in adults with existing heart disease and excess weight, and MASH. Trials also show benefits for kidney outcomes in people with diabetes and chronic kidney disease [2][3][4]. ## How does semaglutide work? It activates the GLP-1 receptor, which increases insulin release only when blood sugar is elevated, suppresses glucagon, and slows stomach emptying — reducing after-meal blood-sugar spikes. ## How does semaglutide work for weight loss? Its weight effect is centered in the brain: it reaches appetite-control circuits in the hypothalamus and brainstem, reducing hunger signaling and food preoccupation without measurably lowering resting energy expenditure [6]. ## What is tirzepatide? Tirzepatide is a synthetic 39-amino-acid peptide that activates both the GLP-1 and GIP receptors — the first approved dual incretin agonist. It outperformed semaglutide on weight loss in a 72-week head-to-head trial, -20.2% versus -13.7% [1]. ## How does tirzepatide work? By engaging both the GLP-1 and GIP receptors with a single molecule, it amplifies the same glucose-dependent insulin release, glucagon suppression, and appetite-reduction effects semaglutide produces through GLP-1 alone, with GIP receptor activation adding effects on fat metabolism [8]. ## What does tirzepatide do in the body? It lowers blood sugar by boosting glucose-dependent insulin secretion and suppressing glucagon, slows gastric emptying, and reduces appetite and food intake — producing larger glycaemic and weight effects in trials than GLP-1 agonism alone [8][11]. ## What is tirzepatide used for? It is FDA-approved for type 2 diabetes, chronic weight management, and moderate-to-severe obstructive sleep apnea in adults with obesity. ## What is tesamorelin? Tesamorelin is a synthetic 44-amino-acid analogue of growth hormone-releasing hormone (GHRH), FDA-approved in 2010 for one specific use: reducing excess abdominal fat in people with HIV-associated lipodystrophy [13]. ## What does tesamorelin do? It stimulates the pituitary gland to release more of the body's own growth hormone, which raises IGF-1 and preferentially promotes loss of visceral (internal-organ) fat. A 2026 meta-analysis found it reduced visceral fat by an average of 27.71 cm2 versus placebo across pooled trials [12]. ## How does tesamorelin work? It binds the GHRH receptor on pituitary cells, amplifying the body's own pulsatile growth-hormone rhythm rather than replacing it with a constant external dose — a mechanistic distinction from injecting growth hormone directly. ## Will tesamorelin help me lose belly fat? This site does not give individual medical advice or recommend any use. What can be reported is that tesamorelin's approval trials, run specifically in people with HIV-associated lipodystrophy, found significant reductions in visceral (deep abdominal) fat that reversed once treatment stopped [12][16]. Whether that generalizes outside the studied population has not been established by the approval trials. ## What does BPC-157 do in the body? In animal and laboratory models, BPC-157 is associated with faster healing of gastric ulcers and improved recovery of tendons, ligaments, and blood vessels, proposed to work primarily through promoting new blood-vessel growth (angiogenesis) [20][21]. Human evidence remains extremely limited — a 2025 review found only three small human pilot studies [18]. ## Is BPC-157 a growth hormone? No. BPC-157 is a 15-amino-acid gastric-protein-derived peptide with a proposed angiogenesis-based mechanism; it does not act on the growth-hormone axis the way tesamorelin does. That said, one proposed pathway involves sensitizing growth-hormone receptors specifically in tendon cells, which is distinct from stimulating systemic growth-hormone release. ## Does BPC-157 work immediately? The published animal research does not support a claim of immediate effect, and there is no controlled human trial establishing a timeline of any kind. Anecdotal community reports describe effects emerging over one to three weeks, but that is self-reported and not clinical evidence. ## Does BPC-157 damage the liver? No dedicated hepatotoxicity data for BPC-157 exist in the signed research corpus behind this site, and it should not be described as either liver-safe or liver-damaging on current evidence — the human evidence base overall is limited to a two-person intravenous safety pilot that found no measurable change in hepatic biomarkers, which is far too small a sample to draw a general conclusion [17]. --- API Peptide traces each compound from lab molecule to (sometimes) licensed drug and back only as far as the citation trail actually goes — an editorial desk, not a clinic, a pharmacy, or a source.