Visceral fat is known to be a risk factor for a number of diseases but until now it has not been clear how to most effectively reduce it and how to measure the changes.

Researchers at UT Southwestern Medical Centre analysed two types of interventions, an exercise programme and a pharmacological one in order to understand the different effects on this visceral fat.

“Visceral fat can affect local organs or the entire body system,” explains Dr Ian J. Neeland, assistant professor of internal medicine. “When studies use weight or body mass index as a metric, we don't know if the interventions are reducing fat everywhere in the body, or just near the surface.”

Researchers evaluated changes in visceral fat in 3,602 participants over a six month period measured by a CT or MRI exam. Both interventions resulted in less visceral fat, but the reductions were more significant with exercise.

“The location and type of fat is important,” said Neeland. “If you just measure weight or BMI, you can underestimate the benefit to your health of losing weight.”

Participants in the exercise programme were 65% female, with a mean age of 54 and starting BMI at 31. The majority of exercise trials were performed in the US and Canada, while pharmacologic trials also included Sweden, Japan, and four multinational cohorts.

Fat used to be conceptualised as an inert storage centre but over the past decade or so researchers have come to think of it as an active organ that secretes hormones throughout the body. “Some people who are obese get heart disease, diabetes, or metabolic syndrome – and others don't,” said Neeland. “Our study suggests that a combination of approaches can help lower visceral fat and potentially prevent these diseases.”

These results have important implications for healthcare professionals working to improve health in obese patients. Although exercise is not an easy behaviour to target in these individuals, it is the most effective.