"You may have heard about brown fat  a unique type of fat that acts like a furnace in the body to burn calories instead of storing them as excess weight https Adults dont have much brown fat but a new study suggests that hormones produced by the heart https just might help them make more. Researchers found that the hormones known as cardiac natriuretic peptides caused regular energystoring white fat cells to turn into energyburning brown fat in mice. If studies show the same thing in humans the heart hormone may hold the key to an effective weight loss https treatment says researcher Sheila Collins PhD of SanfordBurnham Medical Research Institute in Orlando Fla. The study appears online in the Journal of Clinical Investigation. These hormones are involved in fluid regulation but we showed in this study that they also play a role in breaking down fat she says. Brown Fat and Heart Hormones Collins and colleagues have long studied how the bodys adrenaline system regulates fat storage and weight loss. In their latest work they showed that the heartderived hormones activate the same fatburning process as the adrenaline pathway and that the two systems can work together to promote the browning of fat cells. When they exposed mice to cold the mice exhibited elevated amounts of natriuretic peptides in their circulatory systems which turned on the fatburning brown fat. A separate study in humans published late last month suggested that cold stimulates the calorieburning potential of brown fat. In this study six volunteers were placed in a chilled room while researchers conducted tests to measure fat metabolism https When the men got cold but were not cold enough to shiver their metabolic rate https increased by  and they burned an additional  calories over three hours. The additional energy expenditure was caused by brown fat burning ordinary fat. Brown Fat Hype Exceeds Science The goal of the research is to develop effective treatments for weight loss aimed at increasing brown fat or stimulating its fatburning potential. David Katz MD who directs the Yale Prevention Research Center says the hype about brown fat has far exceeded the science and he remains unconvinced that such treatments are possible. Weve been here many times before he says. If we were able to stimulate brown fat and if that proved to be effective for weight loss  two big ifs  the likelihood that this would involve unintended harms is great. He says the focus on finding a quickfix treatment for obesity https distracts from the reality that the obesity https epidemic is a result of people eating too much and doing too little. Our species has intricate overlapping metabolic defenses to prevent starvation because if they werent there we wouldnt be here he says. Every time we think we have found a way to shut that off we have ended up being wrong."