ICD-10 · E66
Obesity
Obesity is a chronic, relapsing disease defined by excess body fat that increases health risk. The medical threshold is BMI ≥30, or ≥27 with a weight-related comorbidity. GLP-1 medications Wegovy and Zepbound are FDA-approved for chronic weight management and produce 14–21% mean weight loss in clinical trials.
Medically reviewed by Dr. Jane Novak, MD, MPH on June 1, 2026
This is general health information, not medical advice. Talk to a licensed clinician about diagnosis and treatment options.
Overview
Symptoms
- BMI ≥30
- Difficulty with physical activity
- Shortness of breath
- Joint pain
- Sleep difficulties
Risk factors
- Genetics
- Sedentary lifestyle
- High-calorie diet
- Certain medications (steroids, antipsychotics)
- Sleep deprivation
- Endocrine disorders
Treatment options
- Lifestyle modification
- GLP-1 receptor agonists
- Other anti-obesity medications
- Bariatric surgery (BMI ≥35-40)
GLP-1 evidence for chronic weight management
Editorial grades summarizing study quality and convergence. How we grade.
| Claim | Grade | Basis |
|---|---|---|
Semaglutide 2.4 mg produces ~14-15% body-weight reduction at 68 weeks Source: NEJM, 2021 STEP-1 (n=1,961) and STEP-3 RCTs with converging results | AStrong evidence | STEP-1 (n=1,961) and STEP-3 RCTs with converging results |
Tirzepatide 15 mg produces ~22% body-weight reduction at 72 weeks Source: NEJM, 2022 SURMOUNT-1 (n=2,539); class-leading effect size | AStrong evidence | SURMOUNT-1 (n=2,539); class-leading effect size |
Weight regain is the norm if therapy is stopped Source: JAMA, 2023 STEP-1 extension and SURMOUNT-4: ~2/3 of lost weight regained within 12 months | AStrong evidence | STEP-1 extension and SURMOUNT-4: ~2/3 of lost weight regained within 12 months |
Semaglutide reduces cardiovascular events in adults with obesity (no diabetes) Source: NEJM, 2023 SELECT (n=17,604), 20% MACE reduction | AStrong evidence | SELECT (n=17,604), 20% MACE reduction |
Long-term GLP-1 use causes medullary thyroid cancer in humans Source: accessdata.fda.gov Rodent-only signal; no human cases attributed despite 10+ years post-approval | FNo evidence | Rodent-only signal; no human cases attributed despite 10+ years post-approval |
Related GLP-1 medications
Ozempic
GLP-1 receptor agonist · ~$997.58/mo
View detailsWegovy
GLP-1 receptor agonist · ~$1349.02/mo
View detailsZepbound
GIP/GLP-1 dual receptor agonist · ~$1059.87/mo
View detailsNot sure which medication is right for you? Our quiz matches you with providers based on state, insurance, and budget.
Take the GLP-1 quizCommon questions readers ask
- Do I need to exercise on Wegovy?
- Yes — resistance training specifically. Without it, 25-40% of weight lost on GLP-1 comes from lean muscle. Cardio is a bonus; resistance is the non-negotiable. Full evidence-graded answer
- How fast do results show on GLP-1?
- Appetite changes in 1-2 weeks. Visible weight loss usually starts in week 4-6. Significant fat loss accelerates in weeks 12-44 as the dose escalates. Full evidence-graded answer
- Why am I not losing weight on Wegovy?
- Most non-responders fall into 4 buckets: dose hasn't reached maintenance (2.4 mg), titration was interrupted, calorie intake creeps to match satiety, or a hormonal/medical confounder (hypothyroid, PCOS-with-insulin-resistance, sleep apnea). Talk to your prescriber if no measurable loss by week 16 at maintenance dose. Full evidence-graded answer
- Can I build muscle on a GLP-1?
- Yes — with deliberate resistance training and adequate protein. Without it, 25-40% of weight lost on GLP-1 comes from lean muscle. Lifting 2-3x/week + 1.2-1.6 g/kg ideal-body-weight protein preserves and can grow muscle while losing fat. Full evidence-graded answer
- Can GLP-1 help with PCOS?
- Yes — primarily via weight loss and improved insulin sensitivity. Smaller trials show improved ovulatory cycles and reduced androgen symptoms in women with PCOS. No GLP-1 is FDA-approved for PCOS; use is off-label and weight-driven. Full evidence-graded answer
- Does GLP-1 work for type 1 diabetes?
- No GLP-1 is FDA-approved for type 1 diabetes. Some endocrinologists prescribe semaglutide off-label as an insulin adjunct in T1D with obesity or insulin resistance, but evidence is limited and DKA risk during gastric-emptying changes requires careful monitoring. Full evidence-graded answer
Sources
- Pharmacological Management of Obesity — Endocrine Society Clinical Practice Guideline
- Adult BMI categories — CDC
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