Most adults qualify for prescription weight loss medication if they have a BMI of 30 or higher, or a BMI of 27 or higher with at least one weight-related health condition such as type 2 diabetes or high blood pressure. These have been the standard thresholds for decades, though recent FDA label changes for newer medications have started to shift away from rigid BMI cutoffs. In all cases, you’re expected to have already tried diet, exercise, and behavioral changes before starting medication.
The Core BMI Thresholds
The FDA has historically used two tiers to determine who can be prescribed weight loss drugs. The first is straightforward: a BMI of 30 or above, which falls into the clinical category of obesity. At this level, no additional health conditions are needed to qualify. The second tier covers people with a BMI between 27 and 29.9 (classified as overweight) who also have at least one obesity-related complication.
That said, several newer medications, including semaglutide (Wegovy) and tirzepatide (Zepbound), no longer include specific BMI numbers on their FDA labels. Instead, their approved uses refer more broadly to adults with “obesity” or adults with “overweight in the presence of at least one weight-related comorbid condition.” In practice, most prescribers and insurance companies still rely on the 30/27 thresholds to make decisions, but the shift in labeling signals a move toward treating obesity based on overall health rather than a single number on a scale.
Health Conditions That Lower the BMI Requirement
If your BMI falls between 27 and 30, you can still qualify when you have a related medical condition. The list of qualifying conditions is broader than many people realize:
- Type 2 diabetes
- High blood pressure (hypertension)
- High cholesterol or abnormal blood lipids (dyslipidemia)
- Heart disease or a history of cardiovascular events
- Obstructive sleep apnea
- Fatty liver disease (MASH/NASH)
- Osteoarthritis
- Polycystic ovary syndrome (PCOS)
Having even one of these conditions is enough to meet the threshold. Your doctor will typically confirm the condition through your existing medical history or basic lab work rather than requiring extensive new testing.
Newer Medications Have Expanded Indications
Wegovy’s FDA label now covers three distinct uses. Beyond weight management, it’s approved to reduce the risk of heart attack, stroke, and cardiovascular death in adults who have established heart disease along with obesity or overweight. It also has a separate approval for treating a form of fatty liver disease (noncirrhotic MASH with moderate to advanced fibrosis). This means some people qualify for these medications based on cardiovascular or liver conditions, not just weight loss goals.
Insurance coverage often lags behind FDA approvals. Some Medicaid programs are pulling back on covering GLP-1 medications for weight management specifically. North Carolina’s Medicaid program, for example, is discontinuing coverage of GLP-1s for obesity treatment as of October 2025 while still covering them for diabetes, cardiovascular risk reduction, fatty liver disease, and severe sleep apnea. Private insurance plans vary widely, and many require prior authorization that includes documenting your BMI, related conditions, and previous weight loss attempts.
The Lifestyle Requirement
Weight loss medications are approved as add-ons to lifestyle changes, not replacements. Every major clinical guideline frames pharmacotherapy as something to consider after dietary changes, increased physical activity, and behavioral therapy haven’t produced sufficient results on their own. This isn’t just a formality. Most prescribers and insurance companies want documentation that you’ve made meaningful efforts to lose weight through non-drug approaches before they’ll approve a prescription.
What counts as “sufficient” effort isn’t strictly defined, but a common benchmark is three to six months of consistent lifestyle modification without achieving clinically meaningful weight loss (typically 5% of your starting weight). Some providers are more flexible, particularly when your BMI is well above 30 or you have serious related health conditions that make waiting risky.
Who Qualifies Among Teens and Children
Weight loss medications are no longer limited to adults. Wegovy (semaglutide) is approved for patients aged 12 and older who meet BMI criteria for obesity. An earlier medication, Saxenda (liraglutide), was approved for the same age group, specifically for teens with a BMI at or above the 95th percentile for their age and sex (corresponding to a BMI of 30 or higher in adults) and who weigh more than 132 pounds. Pediatric prescribing follows the same general principle: lifestyle changes come first, and medication is added when those haven’t been enough.
Who Should Not Take These Medications
Certain medical histories rule out specific weight loss drugs entirely. GLP-1 medications like semaglutide and tirzepatide carry a contraindication for anyone with a personal or family history of medullary thyroid cancer or a condition called multiple endocrine neoplasia syndrome type 2 (MEN2). These warnings stem from thyroid tumor findings in animal studies and ongoing monitoring through the FDA’s adverse event reporting system. Before starting a GLP-1, your prescriber will ask about your thyroid and cancer history.
Pregnancy is a universal contraindication across all weight loss medications. A history of pancreatitis may also disqualify you from GLP-1 drugs specifically, and people with certain eating disorders may not be appropriate candidates. Older stimulant-based options like phentermine are generally off-limits if you have uncontrolled high blood pressure, heart disease, or hyperthyroidism.
What Happens During the Screening Process
The screening for weight loss medication is typically straightforward. Your provider will measure your BMI, review your medical history, and confirm any weight-related conditions. Blood work may include a check of your blood sugar levels (A1c), kidney function, liver enzymes, and a thyroid panel, depending on which medication is being considered. If you’re being prescribed a GLP-1 and have no history of diabetes, some contexts require an A1c of 6.4 or less to confirm you don’t have undiagnosed diabetes that would change the treatment approach.
The visit itself often focuses as much on your weight history as your current health. Expect questions about previous diets, exercise habits, weight loss attempts, and how long you’ve been at your current weight. Providers use this information both for clinical decision-making and for the prior authorization paperwork that insurance companies often require.
Staying on Medication Long Term
Qualifying initially doesn’t guarantee indefinite access. Most guidelines recommend reassessing your response within the first three to four months. For phentermine/topiramate, the benchmark is specific: if you haven’t lost at least 3% of your body weight by 12 weeks, your dose gets increased, and if you still haven’t lost 5% at the higher dose after another 12 weeks, the medication should be tapered off. For liraglutide, losing at least 4% of your body weight by week 16 is a strong predictor of long-term success.
Follow-up visits every three to six months are standard to track weight changes, metabolic markers, and side effects. If a medication isn’t working, your provider will typically switch to a different option rather than continuing indefinitely. These ongoing check-ins aren’t just gatekeeping. They help identify whether the medication is doing enough to justify the cost, side effects, and commitment of staying on it.