Chock-full of vitamins and omega-3 fatty acids, fish has gained quite the reputation for keeping our hearts and brains healthy, but new research suggests it could also play a very active role in weight loss. Japanese scientists have found that fish oil converts fat-storing cells into critical fat-burning cells, which could help battle obesity as these cells decrease later in life.

White fat cells are the culprits behind obesity, storing excess energy which leads to love handles and beer bellies if it goes unused. Brown fat cells on the other hand mostly perform the role of burning fat to generate heat and keep the body warm. Much obesity-related research has been aimed at unearthing mechanisms that produce more of the good fat and less of the bad, with the recent discoveries of proteins, hormones and even environmental factors showing some promise in this regard.

These efforts received a further boost in 2012, when scientists discovered a third type of fat cells described as beige. These promised to provide a new therapeutic target for treating obesity, with the researchers finding that they share the fat-burning abilities of brown cells, though they do decrease in number as we approach middle age.

It is this last attribute that researchers at Japan's Kyoto University set out to explore. What if the beige fat cell numbers could be boosted again by eating certain foods? Aware that fish oil had been shown to carry a number of different health benefits, the team examined its effects on beige fat cell counts in mice.

The researchers fed a group of mice a diet of fatty foods, and other groups the same fatty foods with fish oil additives. The group consuming the fish oil gained 5 to 10 percent less weight and 15 to 25 percent less fat over the course of the experiment. The team says that this is a result of the oil triggering receptors in the digestive tract, activating the sympathetic nervous system and converting white fat cells into the beige variety.

"People have said that food from Japan and the Mediterranean regions contributes to longevity, but why it was good was up for debate," said study senior author Teruo Kawada. "Now we have better insight into why that is."

The research was published in the journal Scientific Reports.

Source: Kyoto University