How fast do GLP-1s cause weight loss?

In trials, weight fell steadily for about a year before plateauing. Early months often bring smaller losses while doses are increased.

Are GLP-1s approved for weight loss without diabetes?

Yes. Wegovy, Zepbound, Saxenda and Foundayo carry weight-management labels for adults with obesity, or overweight with a weight-related condition.

Which GLP-1 causes the most weight loss?

In the SURMOUNT-5 head-to-head trial, tirzepatide (Zepbound) produced more average weight loss than semaglutide (Wegovy): 20.2% vs 13.7% at 72 weeks.

Do you regain weight after stopping a GLP-1?

Trials that stopped treatment found substantial regain on average. Long-term plans are a prescriber conversation.

GLP-1 Drugs for Weight Loss: What the Trials Show

GLP-1 for weight loss: which drugs are approved, what major trials showed (including head-to-head), side effects and what users report. Not medical advice.

Anonymous user report. Not medical advice. Peptides discussed are not FDA-approved for the uses described. Editorial process →

Short answer

US drugs with weight-management approval in this class are Wegovy (semaglutide injection and pill), Zepbound (tirzepatide), Saxenda (liraglutide) and Foundayo (orforglipron). In the SURMOUNT-5 head-to-head trial, adults with obesity lost on average 20.2% of body weight with tirzepatide vs 13.7% with semaglutide over 72 weeks. Separate trials reported about 16.6% with the Wegovy pill (on-treatment) and 11.2% with orforglipron (all randomised participants). Averages hide wide individual variation, trials included diet and activity support, and weight often returns after stopping. Ozempic and Mounjaro are diabetes brands; their use for weight loss alone is off-label. Peptide Confessions does not publish dosing, timing, injection or sourcing guidance.

Major trials at a glance

Last reviewed October 15, 2026. Averages from published trials; individual results vary widely.

Drug	Trial	Average weight loss vs placebo
Tirzepatide (Zepbound)	SURMOUNT-1, 72 weeks	Up to about 21% vs about 3%
Semaglutide (Wegovy)	STEP 1, 68 weeks	About 15% vs about 2%
Liraglutide (Saxenda)	SCALE, 56 weeks	About 8% vs about 3%
Tirzepatide vs semaglutide	SURMOUNT-5, 72 weeks, head-to-head	20.2% vs 13.7%

How GLP-1s cause weight loss

They act on appetite centres in the brain and slow stomach emptying, so people feel full sooner and think about food less ("food noise"). Most of the weight lost is fat, but a meaningful share is lean mass, which is why protein and resistance training come up so often (Ozempic muscle loss). Basics: what is GLP-1?.

Side effects and what happens when you stop

Gastrointestinal effects are the main side effects (GLP-1 side effects). When treatment stops, appetite tends to return and trials show substantial regain: about two-thirds of lost weight within a year in the STEP 1 extension.

What users report here

Switchers often compare drugs: #384 says semaglutide "just made eating too much feel miserable" while tirzepatide brought "0 interest", and #194 forgets lunch entirely after switching. Unexpected effects come up too: less drinking (#104), fewer migraines (#105).

Regain is the commonest complaint: #200 regained 30 of 50 lb in four months after stopping; #87 says food noise returned within three weeks. Browse semaglutide and tirzepatide reports. Stories, not rates.

More confessions from the archive

Community Q&A

How fast do GLP-1s cause weight loss?: In trials, weight fell steadily for about a year before plateauing. Early months often bring smaller losses while doses are increased.
Are GLP-1s approved for weight loss without diabetes?: Yes. Wegovy, Zepbound, Saxenda and Foundayo carry weight-management labels for adults with obesity, or overweight with a weight-related condition.
Which GLP-1 causes the most weight loss?: In the SURMOUNT-5 head-to-head trial, tirzepatide (Zepbound) produced more average weight loss than semaglutide (Wegovy): 20.2% vs 13.7% at 72 weeks.
Do you regain weight after stopping a GLP-1?: Trials that stopped treatment found substantial regain on average. Long-term plans are a prescriber conversation.
Does this page give dosing advice?: Peptide Confessions does not publish dosing, timing, injection or sourcing guidance.

Sources

Anonymous first-hand reports plus sourced context — educational only, not medical advice. Editorial policy & corrections.