Eating disorders like anorexia are much more common in girls.
Medical experts think some boys are shy about talking about their eating habits because they see them as girls' problems.
It seems adults are guilty of this way of thinking, too.
The survey of medical experts found that many parents and doctors are missing clues that boys are suffering from eating problems.
One boy said doctors was baffled when he went to see them about his weight loss.
They sent him for tests, which showed there was nothing wrong with his insides.
"They never even considered I might have an eating disorder," he said.
"They didn't really know what to do."
Luckily, this boy did eventually get the right help and he's now completely recovered from his illness.