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Body Mass Index (BMI) is a simple tool that uses height and weight to estimate whether your weight falls within a healthy range. It doesn't directly measure body fat, but gives a quick overview of whether you're underweight, normal weight, or overweight. Healthcare professionals often use BMI as an initial screening tool, but not for diagnosis. It can indicate potential weight-related risks, such as type 2 diabetes or heart disease, and help determine whether someone might benefit from medically supported weight loss treatments. However, BMI is only part of the overall picture. It doesn't account for muscle mass, bone density, or body fat distribution. All of these factors can affect your health independently of BMI. Age, biological sex, and ethnicity also aren't taken into account, even though they play an important role in body composition and overall risk. Still, research shows that BMI remains a useful starting point when combined with other measurements such as waist circumference or metabolic health indicators. That's why at Reboost we use BMI as one of several factors to help doctors form a complete picture before recommending treatment.

BMI is calculated by dividing weight in kilograms by height in meters squared (kg/m²). BMI = weight (kg) ÷ [height (m)]². For imperial units: BMI = [weight (lb) ÷ height² (in²)] × 703. BMI results for adults aged 20 and over are generally classified into the following categories:

Once you've calculated your BMI, you'll see which range your result falls into. Underweight (<18.5): May increase the risk of malnutrition, a weakened immune system, or osteoporosis. Healthy weight (18.5–24.9): Generally associated with the lowest overall risk of chronic disease. Overweight (25–29.9): May increase the risk of high blood pressure, insulin resistance, and heart disease. Obesity class 1 (30–34.9): Associated with a higher risk of type 2 diabetes, high blood pressure, and sleep apnea. Obesity class 2 (35–39.9): Often associated with a higher risk of heart disease, mobility issues, and liver complications. Obesity class 3 (>40): Carries the highest risk of chronic conditions such as diabetes, cardiovascular disease, and certain cancers.

BMI has its limitations. Muscle vs. fat: BMI doesn't distinguish between lean muscle mass and body fat. Fat distribution: Visceral fat can raise health risks more than fat in other areas. Metabolic health: BMI doesn't measure blood sugar, cholesterol, blood pressure, or inflammation. Fitness level: A higher BMI doesn't rule out fitness and metabolic health. Age, sex, and genetics: Affect health but aren't factored into BMI. Ethnicity: BMI thresholds don't apply equally to all groups. Lifestyle: Sleep, diet, stress, and activity affect health but aren't captured by BMI.

Think of your BMI result as a starting point, not a final answer. It provides context, not a diagnosis. If your BMI is in the healthy range, it's still worth keeping an eye on blood pressure, energy levels, and nutrition. A BMI outside the healthy range is a signal to look closer — not a diagnosis. At Reboost, licensed doctors review your complete health profile — BMI, lifestyle, medical history, and goals — to recommend the right treatment or support plan. Whatever your number, you deserve guidance that fits your body and your life.