Washington ? Children who drink more than three servings of milk each day are prone to becoming overweight, according to a large new study that undermines a heavily advertised dairy industry claim that milk helps people lose weight.

The study of more than 12,000 children nationwide found that the more milk they drank, the more weight they gained: Those consuming more than three servings each day were about 35 percent more likely to become overweight than those who drank one or two.

“The take-home message is that children should not be drinking milk as a means of losing weight or trying to control weight,” said Catherine Berkey of Harvard Medical School and Brigham and Women’s Hospital in Boston, who led the study, the largest to examine the question in children.

The National Dairy Council has spent $200 million since 2003 to promote the idea that milk can help people lose weight. Some research has suggested that calcium or other elements in milk may cause the body to make less fat and speed its elimination, but the studies produced mixed results.

“I went into this project expecting that drinking milk would have some weight benefit for children. So I was surprised when it turned out the way it did,” said Berkey, whose findings are being published in the June issue of the journal Archives of Pediatrics & Adolescent Medicine. “The studies are all over the place, but the dairy industry tells children and adults, ‘Drink more milk and you will lose weight.’ I think that’s misleading.”

The dairy industry disputed the idea that the new study challenges its ads, saying it had said only that adults may be able to lose more weight if they drink milk while cutting calories.

“Our message has always been very conservative – that three servings a day as part of a reduced-calorie diet may help promote weight loss,” said Isabel Maples, a dietician speaking for the council. “Most children don’t even get one serving a day” of milk.

For the study, Berkey and her colleagues analyzed data collected from about 12,829 children from all 50 states who were ages 9 to 14 in 1996, when they began participating in the Growing Up Today Study, an ongoing project examining the relationship between diet, exercise and other lifestyle factors.

The researchers examined the relationship between the children’s milk intake between 1996 and 1999 and their weight over a one-year period. Those who drank more than three eight-ounce servings of milk a day gained the most weight, even after the researchers took into consideration factors such as physical activity, time spent on television and video games, other dietary factors, and growth. The association held, even though most of the children were drinking low-fat milk.