A chemical found in chili peppers that is being touted as a weight loss aid may not be as useful as its manufacturer would like people to think, a new study suggests.

Japanese food maker Ajinomoto claims that this chemical-called dihydrocapsiate-is “a great tool for weight management” that helps people burn calories, the company’s Jun Tashiro told Reuters Health.

However, researchers found no change in body weight and only a small increase of around 50 more calories burned per day after people took a pill containing the compound.

They also did not find a significantly larger effect in high doses of dihydrocapsiate, for which they had chosen a goal of 75 calories burned per day. The researchers concluded that the compound had a relatively weak effect.

Dr. Soren Snitker, a professor at University of Maryland School of Medicine who was not involved with the study, pointed out that making this judgment depends on how one looks at the data.

“The researchers chose 75 calories per day because that’s what they thought was physiologically interesting,” Dr. Snitker told Reuters Health. “But it’s not very well understood what kind of change you would need to get a particular amount of weight loss.”

In other words, the 50-calorie per day increase is small compared to the 75-calorie increase they had hoped to see, though even the effects of that higher mark are, according to Snitker, unclear.

There are 3500 calories in a pound. If you’re burning 75 calories a day, it would take about 46 days to lose one pound.

Scientists and nutritionists are interested in dihydrocapsiate as a dietary supplement because it is closely related to capsaicin, another chemical found in peppers. Capsaicin has already been shown to help increase metabolism, but because it is has an extremely hot taste, the less pungent dihydrocapsiate could provide an alternative.

To investigate dihydrocapsiate’s effect on calories burned, researchers gave 78 healthy men a pill with 0, 3, or 9 milligrams of the dihydrocapsiate, once a day for 4 weeks. The increase of 50 calories burned per day was only found after the researchers combined the data from the two groups receiving the supplement-separately, the two groups showed no significant effect.

Ajinomoto’s recommended daily dose for Capsiate Natura contains 3 milligrams of dihydrocapsiate, or the equivalent of 10 cayenne peppers. But, Tashiro explained, most people either can’t eat that many cayenne peppers in a day because it upsets their stomach, or they just don’t like the flavor.

He also pointed out that Capsiate Natura is only available in the U.S. through doctors-it’s not yet available over the counter.

“When it comes to supplements that increase metabolism, there aren’t many options out there that are substantiated by the FDA,” said Tashiro. “There are good guys and bad guys. We are trying to be good by marketing to doctors first.”

Still, Eric Ravussin, lead author of the study and researcher at Pennington Biomedical Research Center in Baton Rouge, Louisiana, said that his findings suggest the effects of dihydrocapsiate are negligible.

“Taking this as a supplement might be helpful but is not very relevant to weight loss overall,” Ravussin told Reuters Health. “Even with an increase in metabolism by 50 calories, any weight loss would offset it.”

He explained that anytime you lose weight, whether by exercise or changing your diet, your metabolism goes down in order to maintain an energy balance-if you have less weight to move, your body needs to burn fewer calories each day.

To Snitker, this could suggest that dihydrocapsiate may be more effective as part of a calorie-cutting diet, working to help keep metabolism up when it would otherwise be reduced.

“The problem with being on a diet is your body compensates for the weight loss,” he said. “It would be interesting to look at what happens when you add capsiates to a weight-loss diet.”

SOURCE:  American Journal of Clinical Nutrition, 2010.