A body composition scan generates a detailed report of your physical makeup, but the numbers are only useful if you know how to read them. Most people glance at their weight and body fat percentage, then file the report away. The scan actually tells a much richer story, one that reveals your metabolic health, muscle balance, visceral fat risk, and whether your current nutrition and training approach is working.

Body Fat Percentage

Body fat percentage is the proportion of your total body mass that is adipose tissue. Healthy ranges vary by sex and age. For men, 10 to 20% is generally considered healthy, with athletic ranges at 8 to 15%. For women, 18 to 28% is healthy, with athletic ranges at 15 to 22%.

Context matters more than absolute numbers. A body fat percentage of 25% in a 25-year-old woman is different from 25% in a 55-year-old man. Your coach interprets your number within the context of your age, sex, goals, and health history.

Skeletal Muscle Mass

This is the total mass of muscle attached to your skeleton, measured in kilograms. It is the single most important metric for long-term metabolic health because muscle mass drives basal metabolic rate, improves insulin sensitivity, protects bone density, and is the strongest predictor of physical independence in later life.

Healthy skeletal muscle mass depends on your frame size and sex. As a general guideline, men should aim for skeletal muscle mass representing at least 40% of total body weight, and women at least 30%.

Visceral Fat Level

Visceral fat is the fat stored around your abdominal organs. Unlike subcutaneous fat (which sits beneath the skin), visceral fat is metabolically active, producing inflammatory cytokines and hormones that increase the risk of type 2 diabetes, cardiovascular disease, and certain cancers.

BIA scanners typically report visceral fat on a scale of 1 to 20. Levels of 1 to 9 are considered normal, with 10 and above indicating elevated risk. This metric is particularly important because someone with a normal BMI can carry dangerous levels of visceral fat, a condition sometimes called "TOFI" (thin outside, fat inside).

Basal Metabolic Rate and Total Energy Expenditure

Your basal metabolic rate (BMR) is the number of calories your body burns at complete rest to maintain basic functions: breathing, circulation, cell production, and temperature regulation. Total energy expenditure adds activity calories to this baseline.

These numbers are critical for nutrition planning because they establish the caloric framework within which your programme operates. A declining BMR over time, beyond what would be expected from weight loss, can indicate metabolic adaptation that requires programme adjustments.

Segmental Analysis

Advanced BIA scanners break down lean mass and fat mass by body segment: right arm, left arm, trunk, right leg, and left leg. This reveals muscle imbalances between sides that may indicate injury compensation, relative trunk muscle development compared to limbs, and whether training is producing balanced development.

Segmental data is particularly valuable for identifying asymmetries that could lead to injury if left unaddressed.

Common Misinterpretations

Weight gain does not always mean fat gain. Early in a training programme, increases in body weight often reflect muscle gain and increased water retention in muscle tissue. Body fat percentage fluctuates with hydration status. For reliable trends, scan under consistent conditions. BMI is nearly useless for individuals with significant muscle mass, as it cannot distinguish between muscle and fat.

Frequently Asked Questions

My weight went up but my body fat went down. Is that good? Yes, this typically indicates body recomposition, gaining muscle while losing fat. This is one of the best outcomes a nutrition and training programme can produce.

Why does my scan result vary between morning and evening? Hydration, food intake, and exercise all affect BIA readings. For consistent tracking, scan at the same time of day under similar conditions.

How quickly should body composition change? Realistic rates of change are 0.5 to 1.0 percentage points of body fat per month, and 0.5 to 1.0kg of muscle gain per month for beginners (less for experienced trainees). Changes beyond these rates may indicate unsustainable protocols.

Every coaching client gets regular BIA scans with expert interpretation. Start your journey and learn about why body weight is a terrible health measure.