Weight loss and body recomposition: Seeing beyond the numbers on a scale

Even though a scale is still a common tool for measuring our body weight, the body mass index (BMI) takes precedence. The calculation, obtained by dividing weight (kg) by weight squared (m²), was formulated in the 19th century by a Belgian statistician. The term “BMI” was introduced in the 1970s by Ancel Keys, an American physiologist known for American soldiers’ “K rations” and the well-known Mediterranean diet. Since then, BMI has been widely used in medicine and in the insurance sector for assessing the risks of diseases such as diabetes and cardiovascular disease [2].

Over time, the limitations of the BMI have become obvious. BMI tables have had to be adjusted for sex and age, and are still difficult to apply to some populations such as Asian, Black or non-Hispanic individuals, athletes or amputees. For example, very muscular people are often classified as overweight, while other people classified as obese are perfectly healthy. We have since realized that, for the same body index, distribution of fat mass—particularly around the waist—is a greater determinant. As a result, the waist measurement has been introduced as a complementary indicator, with risk thresholds set at 40 inches for men and 35 inches for women.

In short, neither weight, BMI nor waist measurement is enough to reveal our actual body composition. What about the proportion of fat and muscle, in the abdomen and limbs?

Lipodensitometry is an advanced medical imaging technique which analyzes body composition in detail [3]. Unlike BMI or waist measurement, which give an overall estimate of weight and fat distribution, it provides a precise view of the amount and distribution of fat and muscles in our bodies.

Based on the same principle as bone densitometry, like dual-energy X-ray absorption (DEXA) often used for measuring bone density, lipodensitometry offers a more thorough analysis. By measuring the density of different body tissues, it can distinguish subcutaneous fat from visceral fat around organs, and measure muscle mass. This precision gives a detailed overview of an individual’s health and physical state. 

This analysis method is particularly recommended in the following situations: 

• Prevention and diagnosis: recommended for people at high risk of cardiovascular disease or metabolic disorders, such as people who are overweight or diabetic.
• Monitoring body composition: ideal for people who want to track the evolution of their fat and muscle mass, including as part of weight-loss or muscle-building programs.
• Medical follow-up: helpful for monitoring the effect of medical treatments which may change body composition such as some cancer or osteoporosis treatments.

Body recomposition means losing fat mass while maintaining or improving muscle mass. Lipodensitometry is a valuable tool for precisely analyzing this transformation, far beyond simply measuring weight. It can distinguish between fat mass and lean body mass, thereby providing invaluable information for better managing health and wellness. For assessing general health, preventing disease risks or improving a fitness program, lipodensitometry means taking one step closer to better health management.