BMI

BMI (body mass index) is a simple calculation — your weight divided by your height squared — used to sort people into weight categories. You’ll meet it constantly in GLP-1 treatment because it’s the number insurers and prescribers use to decide eligibility. It’s useful as a rough screen and genuinely limited as a measure of any one person.

The categories and why they matter here

The standard adult bands:

• Under 18.5 — underweight
• 18.5–24.9 — “normal”
• 25–29.9 — overweight
• 30 and above — obesity

These thresholds have real consequences for access. Weight-management GLP-1s like Wegovy and Zepbound are typically approved for a BMI ≥ 30, or ≥ 27 with a weight-related condition (such as high blood pressure or type 2 diabetes). That single number often decides whether insurance covers your prescription.

The blind spots

BMI is a population screening tool wearing the costume of an individual diagnosis. Its flaws:

• It can’t tell muscle from fat. A muscular person can register as “overweight” while carrying little fat — the same reason BMI can’t see body recomposition.
• It ignores fat distribution. Visceral (around-the-organs) fat is more metabolically risky than the number alone conveys — which is why waist measurement often adds information.
• It varies across ages, sexes, and ethnic groups, so the same cutoff doesn’t carry the same risk for everyone.

How to use it

Treat BMI as one coarse data point, not a verdict on your health — pair it with waist measurement, bloodwork like A1C, and how you actually feel and function. But also know your number, because in the world of coverage and prescriptions, it’s the gate you have to pass through.