What can affect weight and appetite?
This page explains the evidence and the differences between products. It cannot recommend a weight-loss plan or predict your result.
Weight is affected by many things, including biology, food access, sleep, activity, medicines, illness and surroundings. Prescription medicines such as semaglutide and tirzepatide have different product-specific evidence and risks. Retatrutide is still being studied. Supplements marketed for weight loss are not the same as these medicines.12
On this page
Weight & appetite Choose a step to explore this subject in more detail.
Separate the questions
You might want to know about appetite, body weight, waist size, blood sugar, heart health or keeping weight off. A study that answers one question does not automatically answer the others. To see how a cosmetic injection differs from a weight-loss medicine or peptide, read what “fat dissolving” means.12
Food and movement still matter
The World Health Organization describes a healthy diet in terms of having enough food, balance, moderation and variety. Physical activity can support health and daily function even when weight does not change.
For practical questions about appetite, meals and nausea with these medicines, see eating and drinking with semaglutide or tirzepatide.12
Products and status
When you see a claim, check the exact product, its form, what it is approved for, the country and the date. Peptides and supplements described by sellers as weight-loss products should not be assumed to be approved medicines.
Orlistat works differently from medicines such as semaglutide and can affect vitamin absorption: explore orlistat and vitamin A. An early liver study of a molecule related to MOTS-c is sometimes discussed alongside weight claims: see what it actually measured.123
Semaglutide products
Ozempic, Wegovy and Rybelsus contain the same active ingredient, but they are different products with different approved uses. Read how the semaglutide products compare.
Tirzepatide
Tirzepatide is a medicine with its own product information and trial evidence. Read the tirzepatide profile.
Retatrutide
Retatrutide is still being studied; it is not an approved substitute. Read the retatrutide profile.
Reading weight-loss results
Look at who was studied, what the treatment was compared with and how long people were followed. A group average does not predict an individual result. Read how to read weight-loss results and what studies found after stopping treatment.
If weight loss has slowed, see what a plateau can mean and what the studies measured.
Fat burning, body fat and weight
Using fat as fuel, losing stored body fat and weighing less are different things. Read how fat burning and weight differ and compare peptide claims.45
Growth-hormone signals and body composition
Several peptides affect growth-hormone signalling, but they have different uses and different evidence. Explore the claims about growth-hormone peptides.6
Sources, kept close.
Selected supporting sources; this is not a complete literature review.
- Healthy dietWorld Health Organization · public-health guidance
- Physical Activity and Your Weight and HealthCenters for Disease Control and Prevention · public-health guidance
- XENICAL (orlistat) capsules: US prescribing informationDailyMed / US National Library of Medicine · US product label for Xenical 120 mg capsules; revised September 2026; DailyMed version 3 November 2026
- Overweight and obesity in adultsNational Institutes of Health · Public health overview
- Dietary Supplements for Weight Loss: Health Professional Fact SheetNIH Office of Dietary Supplements · Authoritative evidence overview; supplements, not peptide medicines
- Prolonged stimulation of growth hormone and insulin-like growth factor I secretion by CJC-1295 in healthy adultsJournal of Clinical Endocrinology & Metabolism / PubMed · Two randomised double-blind placebo-controlled human hormone studies; 2006