BOSTON -- The dairy industry has put a lot of money behind an advertising campaign pushing milk to help people lose weight.

But a new study led by researchers from Harvard and Brigham and Women's Hospital in Boston found too much milk has the opposite effect -- especially for kids, reported WCVB-TV in Boston.

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Video: Too Much Of A Good Thing?
Health Library: Nutrition | Children's Health

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"Their argument for weight loss for milk consumption is not substantiated by the evidence," said Dr. Graham Colditz of Brigham and Women's Hospital.

In fact, when it comes to kids, new evidence finds the more milk they drink, the more weight they gain.

"Both the boys and girls who were drinking more than three glasses of milk per day had excess weight gain over a 12-month period," Colditz said.

The study, which is published in Monday's issue of the journal Archives of Pediatrics and Adolescent Medicine, involved 12,000 kids. Those who drank more than three glasses of milk a day were 25 percent more likely to become overweight than those who drank less. Researchers blame calories, whether from whole milk or skim.

Colditz worries the ads send the wrong message.

"We shouldn't be thinking that increasing milk consumption will lead to weight loss," Colditz said.

The National Dairy Council said that's not the intent. It lists 50 studies online linking milk to weight loss.

Plus, the council says, the newest study is simply connecting weight gain in children to excess calories -- not specifically milk. The group says that most teens fall short of the recommended three daily servings of milk and milk products.

"The weight-loss campaign is geared toward adults only. So there's really no connection," said Erin Coffield, spokeswoman for the New England Dairy Council.

But adolescent weight studies are featured right on the council's Web site.

The National Dairy Council also noted that the government said in its 2005 Dietary Guidelines to Americans that "adults and children should not avoid milk and milk products because of concerns that these foods lead to weight gain."

Just about everyone agrees kids need milk to develop strong bones. But experts say two to three servings a day is enough. After that, they should switch to calorie-free water, particularly if the goal is to maintain or lose weight.