For decades, Medicare explicitly excluded anti-obesity medications from Part D coverage. That era is over. The TREAT Act (Treat and Reduce Obesity Act), signed into law as part of broader healthcare legislation in late 2024, removed the statutory exclusion and opened the door for Medicare to cover FDA-approved weight loss drugs starting with 2026 plan year formularies.
This is a massive shift for the roughly 42% of Medicare beneficiaries who meet clinical criteria for obesity. Here is what is actually covered, what it costs, and how to navigate the process.
What the TREAT Act Actually Changed
Since Medicare Part D was created in 2003, the law specifically listed "agents when used for anorexia, weight loss, or weight gain" as a category that Part D plans could not cover. This was not a plan choice — it was a federal statute. Even if a Part D plan wanted to cover Wegovy for weight loss, it legally could not.
The TREAT Act repealed this exclusion. Here is what it did and did not do:
What the TREAT Act Did
- Removed the statutory exclusion of anti-obesity medications from Part D
- Allowed (but did not require) Part D plans to add FDA-approved obesity drugs to their formularies
- Directed CMS to issue guidance on coverage criteria and utilization management
- Established that obesity is a chronic disease eligible for pharmacological treatment under Medicare
What the TREAT Act Did NOT Do
- It did not mandate that every Part D plan cover every anti-obesity drug
- It did not eliminate prior authorization requirements
- It did not set specific cost-sharing limits for obesity medications beyond the existing $2,000 annual cap
- It did not cover compounded versions of GLP-1s (like compounded semaglutide)
Which Weight Loss Medications Medicare Can Now Cover
Not every weight loss drug is on every formulary. But the following FDA-approved anti-obesity medications are now eligible for Part D coverage:
GLP-1 / GIP Agonists for Weight Management
| Medication | Type | Avg. Weight Loss | Part D Coverage Status (2026) |
|---|---|---|---|
| Wegovy (semaglutide 2.4mg) | Injectable, weekly | ~15-17% | Most broadly covered obesity GLP-1 |
| Zepbound (tirzepatide) | Injectable, weekly | ~20-22% | Growing coverage, fewer plans than Wegovy |
| Saxenda (liraglutide 3mg) | Injectable, daily | ~5-8% | Limited coverage (older, less effective) |
Non-GLP-1 Weight Loss Drugs
| Medication | Type | Avg. Weight Loss | Coverage Status |
|---|---|---|---|
| Contrave (naltrexone/bupropion) | Oral, daily | ~5-6% | Covered on some plans (lower cost) |
| Qsymia (phentermine/topiramate) | Oral, daily | ~7-10% | Covered on some plans |
| Orlistat (Xenical) | Oral, with meals | ~3-5% | Some plans (generic available) |
The Diabetes vs. Obesity Coverage Distinction
This is where confusion runs rampant. Many GLP-1 medications exist in two versions — one approved for diabetes, one for obesity:
- Ozempic (diabetes) vs. Wegovy (obesity) — both are semaglutide, but different doses and FDA approvals
- Mounjaro (diabetes) vs. Zepbound (obesity) — both are tirzepatide
If you have type 2 diabetes, your doctor prescribes Ozempic or Mounjaro under the diabetes indication — this has been covered by Part D for years. If you have obesity without diabetes, your doctor prescribes Wegovy or Zepbound under the obesity indication — this is the new coverage that the TREAT Act enabled.
You cannot get Ozempic prescribed "for weight loss" and expect Part D to cover it. The FDA indication on the prescription must match the drug's approved use.
What You Will Actually Pay
Even with coverage, GLP-1s are not cheap. Here is a realistic cost breakdown for a Medicare beneficiary in 2026:
Scenario 1: Good Formulary Placement (Tier 3)
- Monthly copay: $47–$80
- Annual deductible: up to $590
- Estimated annual out-of-pocket: $1,100–$1,550
- You hit the $2,000 cap: likely by month 8–10
- After cap: $0 for the rest of the year
Scenario 2: Specialty Tier (Tier 5)
- Monthly coinsurance: 25–33% of drug cost
- At $1,300/month retail: $325–$430/month coinsurance
- You hit the $2,000 cap: likely by month 2–3
- After cap: $0 for the rest of the year
Here is the silver lining: even in the worst-case scenario with specialty tier placement, the $2,000 annual cap means your maximum cost is $2,000 per year, regardless of how expensive the drug is. Before the Inflation Reduction Act, a beneficiary on a specialty-tier GLP-1 could easily pay $5,000–$8,000 annually out of pocket.
If You Qualify for Extra Help
Medicare's Extra Help (Low Income Subsidy) program dramatically reduces costs for qualifying beneficiaries:
- Full Extra Help: copays of $0–$4.50 per prescription in 2026
- Partial Extra Help: reduced copays and no coverage gap
- Income limit: approximately $22,590/individual or $30,660/couple (2026 guidelines)
Medicare Advantage vs. Original Medicare + Part D
Medicare Advantage (MA) plans that include drug coverage (MA-PD) may handle GLP-1 coverage differently than standalone Part D plans:
- Formulary differences: MA plans often have more restrictive formularies but may negotiate lower copays for drugs they do cover.
- Integrated care management: Some MA plans pair GLP-1 coverage with required participation in a weight management program, which can be beneficial but adds requirements.
- Supplemental benefits: Some MA plans offer nutritional counseling, gym memberships, or meal delivery as part of an obesity management package that complements medication coverage.
- Prior auth speed: MA plans sometimes process prior authorizations faster because the plan controls both medical and pharmacy benefits.
If you are choosing between Original Medicare + standalone Part D and a Medicare Advantage plan, compare the total annual cost for your specific medications using the Medicare Plan Finder tool. The best choice depends entirely on which drugs you take and which plans are available in your zip code.
Lifestyle Modification and Step Therapy Requirements
Most Part D plans require documentation of lifestyle modification attempts before approving GLP-1 coverage for obesity. This typically means:
- 3–6 months of documented diet and exercise participation — this can include a physician-supervised program, a registered dietitian consultation, or a structured commercial program (Weight Watchers, Noom, etc.)
- Documentation in your medical record: Your physician must note that you attempted behavioral modification and it was insufficient for achieving clinically meaningful weight loss (typically defined as ≥5% of body weight)
- Step therapy through lower-cost agents: Some plans require a trial of Contrave, Qsymia, or orlistat before approving a GLP-1. This requirement is increasingly controversial and some plans are dropping it.
Important: if you have a weight-related comorbidity like type 2 diabetes, hypertension, or obstructive sleep apnea, step therapy requirements may be reduced or waived. Your physician's letter of medical necessity should clearly articulate these comorbidities.
Practical Steps to Get Coverage Approved
- Confirm your plan covers the medication. Check your plan's formulary at Medicare.gov or call the plan's member services line.
- Have your physician document everything. BMI history, comorbidities, prior weight loss attempts, lab results, and failed medication trials.
- Submit a thorough prior authorization request. Include the letter of medical necessity, relevant clinical notes, and lab work.
- If denied, appeal immediately. You have 60 days to file a Level 1 appeal (redetermination). Include any additional documentation that addresses the denial reason.
- Request expedited review if needed. If you are currently without medication and your health is at risk, you can request a 72-hour expedited review instead of the standard 7-day timeline.
- Contact your state SHIP counselor. Free, unbiased help navigating Medicare coverage issues is available through your State Health Insurance Assistance Program.
What About Compounded GLP-1s?
Compounded semaglutide and tirzepatide are not covered by Medicare Part D. The TREAT Act specifically applies to FDA-approved medications, and compounded versions do not carry FDA approval. If you are currently using a compounded GLP-1 and switching to Medicare, you will need to transition to a brand-name FDA-approved product to receive coverage.
For guidance on making that transition, see our guide to switching from compounded to branded GLP-1s.
Bottom Line
Medicare coverage for weight loss medications in 2026 represents a historic shift. The TREAT Act removed the statutory barrier, and the $2,000 out-of-pocket cap from the Inflation Reduction Act makes even expensive GLP-1s financially manageable. The process is not frictionless — prior authorization, step therapy, and formulary restrictions still exist — but for millions of Medicare beneficiaries with obesity, FDA-approved treatment is now within reach.
See our complete Medicare Part D GLP-1 guide for detailed coverage tables and plan comparison strategies.