But do these sites give you the straight scoop? Are they providing solid information or just trying to sell a product?
To find out, Consumer Reports Web Watch had a panel of experts visit the top 20 sites.
Only eight were given a good grade. The rest were rated fair or poor.
"Mostly a tendency on those sites to push product rather than have a lot of in depth information about diet and fitness," says Beau Brendler, director of Consumer Reports WebWatch.
"We found that the sites that did best among the ratings were those that provided balanced information and there sold purpose was not to push a particular product."
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