Overview
- Three Cochrane reviews commissioned by the WHO find tirzepatide, semaglutide and liraglutide produce meaningful weight loss versus placebo, but note sparse long-term outcome data and heavy manufacturer involvement in trials that will inform forthcoming WHO guidelines.
- Across trials, tirzepatide averaged about 16% weight loss over 12–18 months, semaglutide about 11% over up to 68 weeks and liraglutide about 4–5%, with higher rates of mostly gastrointestinal side effects than placebo.
- Dietitians report emerging micronutrient deficiencies, including rare scurvy and thiamine deficiency, and warn of lean mass and bone losses, citing reviews that found few studies tracked participants’ diets and calling for integrated dietitian care.
- Evidence from STEP trials shows substantial weight regain after stopping semaglutide, and clinicians recommend ongoing treatment at the lowest effective dose or a careful taper paired with nutrition, exercise, sleep and monitoring to maintain health.
- A Rutgers analysis of patient reviews finds perceived effectiveness drives continuation despite nausea and other GI issues, while physicians stress GLP-1 drugs are medical treatments for eligible patients under supervision with contraindications such as pregnancy, pancreatitis and certain thyroid cancers.