Exercise can help reduce the invisible, fat that affects the internal organs and may cause heart diseases or diabetes, scientists say.
The type of fat you can measure with tape is not the most dangerous, researchers said. The internal, visceral fat, on the other hand, can affect the heart, liver and other organs.
Researchers at University of Texas (UT) Southwestern in the US analysed two types of interventions -- lifestyle modification (exercise) and pharmacological (medicine) -- to learn how best to defeat fat lying deep in the belly.
"Visceral fat can affect local organs or the entire body system. Systemically it can affect your heart and liver, as well as abdominal organs," said Ian J Neeland, assistant professor of at UT Southwestern.
"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," Neeland said.
For the study published in the journal Mayo Clinic Proceedings, researchers evaluated changes in visceral fat in 3,602 participants over a 6-month period measured by a CT or MRI exam.
Both exercise and medicines resulted in less visceral fat, but the reductions were more significant per pound of body weight lost with exercise.
"The location and type of fat is important. If you just measure weight or BMI, you can underestimate the benefit to your health of losing weight," said Neeland.
"Exercise can actually melt visceral fat," he said.
Participants in exercise trials were 65 per cent female, with a mean age of 54 and mean BMI at enrollment of 31.
Researchers previously thought of fat as inert storage, but over the years this view evolved and fat is now seen as an active organ.
"Some people who are obese get heart disease, diabetes, or metabolic syndrome -- and others don't," Neeland said.
"Our study suggests that a combination of approaches can help lower visceral fat and potentially prevent these diseases," he said.