(ABC) -- Good Morning America took a hard look at a brand of workout clothing that claims it can make you burn more calories - by making you hotter. It's certainly selling like hot cakes - with more than a million units sold worldwide.
So ABC's Rebecca Jarvis tried it out, with the help of an expert
Zaggora Hotwear is the trendy fitness wear line with its own YouTube channel. One outfit can cost up to $130. So what makes it different than all the rest?
This company actually claiming on its website that "exercising in Zaggora Hotwear can increase calorie burn."
GMA Investigates wanted to check it out, working with exercise physiologist Polly Demille, at the hospital for special surgery in New York, to help us see would we burn more calories wearing Zaggora clothing?
"If you had somebody doing the same exact work and all you did was change what the person was wearing, you could get an idea of whether the clothing might have any impact," said Demille.
Jarvis wore standard workout clothing. ABC producer Stephanie wore Zaggora.
First they put on headgear and after a warmup, a 30 minute jog at a constant speed. The next morning, they repeated the same workout.
But this time, they flipped and Jarvis wore the Zaggora.
So what did they find?
One case, really no difference whatsoever.
Polly says Jarvis actually burned 3 calories less in Zaggora. And our producer, burned 17 more calories in Zaggora, an 8 percent difference.
The producer was kind of adjusting things a little bit more. So every movement counts. The other possibility is obviously it has something to do with the clothing, but that you know remains to be seen.
On their website Zaggora cites three studies where more than 50 women burned on average between 6 and 11 percent more calories in Zaggora clothing. But exercise physiologist Bill Sukala says their claims could be confusing to consumers.
"You have to look at the actual numbers themselves. The number of calories burnt between using Zaggora hot pants versus other types of athletic wear is very small," Sukala said.
We sent our results to Zaggora who declined an interview, telling us in a statement - "What matters in our business is not opinions but data." Adding about what happened with our demonstration, "even if the readings are assumed to be accurate, it is really not possible to "conclude" anything on the back of one person in each condition doing something."
Dr. Sukala says if you're looking to drop major pounds - think twice.
"When it comes to Zaggora hot pants it's very much a case of wishful shrinking."