Dear Doctor - My Body-Mass-Index is Still High, But I Have Lost Weight - How Do I Know if I Am Healthy

Oct 12, 2026

Explains how Body-Mass-Index (BMI) is calculated and how it classifies weight categories, while highlighting why BMI alone can misjudge health. Discusses key limitations, including differences in muscle mass, early fat gain in lean-built individuals, age-related muscle loss after 65, and the need to treat weight more aggressively when diabetes, hypertension, or cholesterol are present. Introduces alternatives such as waist circumference and hip-to-waist ratio, plus ethnic differences affecting risk.

LanguageEnglish

CategoryForms

FormatPDF

Pages4

Reading Time2 min

AccessFree to download

What is BMI?

Weight category thresholds

Are BMI results always reliable?

Key limitations of BMI

Why body measurements may matter

Waist circumference

Hip-to-waist ratio

“My Body-Mass-Index (BMI) is still high, but I’ve lost weight already. How do I know when I’m healthy?” Answer Provided by Nadia B. Pietrzykowska, MD, FACP To answer this question, let’s first explain what BMI is: The BMI is a formula expressed as a person’s weight in kilograms divided by the square of a person’s height in meters. It is used to classify individuals as having normal weight, less weight than normal or excessive weight. The BMI is a formula that was first invented in the early 1800s by Lambert Adolphe Jacques Quetelet (1796-1874), a Belgian mathematician, statistician, astronomer and sociologist. Later on, it was used by the Metropolitan Life Insurance Company to analyze and classify their policyholder population according to medical risk. Weight Category Underweight < 18.5 Normal 18.5 – 24.9 Overweight 25 – 29.9 Obesity 30 – 39.9 Severe Obesity >40 Is BMI always a good tool to determine healthy weight goals? It certainly is a good starting point. Providers can use this easy calculator to assess their patients’ weight without any equipment other than a scale and a height rod. Unfortunately, it does have limitations and this “one size fits all” approach can be flawed. This is because BMI does not take into account body composition and does not give a good estimate of body fat, muscle mass and other tissues. Why do these proportions matter? Here are some examples showing why relying on BMI alone may result in inaccurate conclusions: Individuals with high musculature may have a high BMI despite having an appropriate weight: Let’s imagine two individuals with the same height and weight standing next to each other. One of themis a professional football player with prominent musculature, and the other is someone with low muscle mass. Their BMI will be the same, but the first individual’s body will be high in muscle and low in fat tissue whereas the second individual’s body will be low in muscle and high in fat tissue. Although they both may have the same high BMI that shows excessive weight, the football player does not have to lose any weight. His “excess weight” is composed of muscle tissue while the second individual may have to lose weight due to excessive fat tissue. When individuals that are “thin built” gain weight, they reach unhealthy amounts offat tissue faster than their BMI can reflect it: These individuals have a naturally low muscle mass. As they gain weight and fat tissue, their BMI may still be in the normal range while their fat tissue proportion is growing to a less-desirable range. These individuals would need weight-loss interventions earlier than expected from the BMI scale. Individuals above the age of 65 are a special group to whom the BMI classification may not always apply: As adults age, they tend to follow the model of the “thin built” individuals described above. In fact, older adults lose muscle mass as they age while gaining fat tissue. They may be reaching high fat tissue amounts faster than their BMI can increase. This said, some studies show that a BMI slightly above normal may be a better and healthier goal for adults in this age range. More research is needed to determine optimal weight goals for this special population. Individuals with weight-related conditions need more aggressive weight-loss interventions: The presence of diseases like Type 2 Diabetes, hypertension and high cholesterol should supersede information provided by the BMI. This means that if an individual has one or more of these diseases, it is crucial to work on losing weight – especially if these conditions appear or worsen with weight gain. While it may be reasonable for someone with obesity who has no other medical conditions to remain at“an overweight BMI of 27,” further weight-loss should be recommended to individuals with weight-related medical conditions. In addition, the presence of pre-disease, specifically prediabetes, should also prompt weight-loss to attempt reversing

FAQs

How is BMI calculated and what does it classify?

BMI is calculated as weight in kilograms divided by the square of height in meters. It is used to classify people into categories such as underweight, normal weight, overweight, obesity, and severe obesity.

Why can BMI be an inaccurate indicator of healthy weight goals?

BMI does not account for body composition, so it can misrepresent body fat and muscle mass. This can lead to incorrect conclusions, such as when someone has high musculature or when changes occur with age.

What other tools besides BMI can help assess weight-related health risk?

Waist circumference helps estimate harmful abdominal fat and supports cardiometabolic risk evaluation. Hip-to-waist ratio is another measure, where lower ratios (under 0.9 for men and under 0.8 for women) are considered healthier.

Oct 12, 2026

Upload by Aria Callaghan