Fat burning and other weight management products made $7.5 billion globally last year. Yet a study has found that those people buying them haven't much of an idea about the benefits of the specific ingredient they put their faith in. And some of these seem very dubious.

Been scammed by acai berry diet claims?  What do you feel about Hoodia gordonni, Citrus aurantium, Caralluma fimbriata and more. No, I can't tell you what they are - I'm not a good enough gardener.

Other popular ingredients enticing consumers towards managing their diets with replacement meals and other solutions include fiber, soy, the whey and casein extracted from milk, and Yerba mate tea.

This must be delighting food manufacturers, given that two thirds of adults in the US and one third of adolescents and children are either overweight or obese - a 48 percent increase among adults in the 10 years from 1988 to 2008, a whopping 72 percent for teenagers and children. After all, the global market for weight loss foods and drinks is estimated by Packaged Facts to be $18 billion.

These are not people in whose interests it is to reveal the truth about weight management: eat sensibly and exercise and be patient. Sounds like the problem people may have encountered in becoming overweight in the first place - a lack of understanding about what makes you fat.

There is no miracle cure. Not even among rainforest tinctures. Just take a look at the horrific number of responses I've had to my warning about the Acai berry diet.