IAEA's stable isotope technique to assess body composition

A person drinks a weighed amount of water, that is labeled with deuterium, a stable isotope of hydrogen.

IAEA will use stable isotope technique to assess body composition to tackle childhood obesity. The IAEA initiative will use the deuterium dilution technique in a sample of school children from the 10 countries to describe the relationship between BMI and body composition. The deuterium dilution technique is a state-of-the-art methodology to assess body composition and thus provides a tool to evaluate the effects of altered diet and physical activity on adiposity.

A person drinks a weighed amount of water, that is labeled with deuterium, a stable isotope of hydrogen.

The water is labeled but is non-radioactive and therefore has no adverse health consequences. After a few hours, the isotope in the labeled water is evenly spread throughout the body water, which can be sampled in the form of saliva or urine.

Deuterium enrichment in saliva is measured using an FTIR or an isotope ratio mass spectrometer (IRMS). Since the amount of deuterium is known, the total volume of body water can be calculated from the enrichment. Based on the assumption, that fat is water-free, scientists can accurately determine the body's ratio of fat and fat-free tissue.

This nuclear technique is accurate and safe to use in all age groups, it is not associated with any radiation hazard, and is suitable for the use in field settings.