Some say there's always room for dessert -- but those who follow that motto young may be more likely to gain unhealthy weight, a new study suggests.

Toddlers who reached for cookies over chips when their bellies were full had a higher risk of body fat increases, University of Michigan researchers report in the May issue of Pediatrics.

"Eating in the absence of hunger is associated with being overweight among older children, but this is the first time we've seen this link in children as young as toddlerhood," says senior author Julie C. Lumeng, M.D., a developmental and behavioral pediatrician at U-M's C.S. Mott Children's Hospital.

"We found that toddlers' eating sweet, but not salty, tasty foods after they already ate a filling meal puts children at a greater risk of weight gain."

For the study, researchers asked 209 low-income mothers to have each child fast for one hour, then eat a substantial lunch. Toddlers were then presented with a tray of sweet treats like chocolate chip cookies and salty snacks like potato chips. They were allowed to eat as much as they wanted.

Children between one and three years old who ate more desserts and who became upset when the food was removed experienced gradual increases in body fat by the time they were 33 months old. Those who picked the salty foods did not.

"The tendency to eat when you're not hungry increases with age and could have lifelong implications for weight gain," says Lumeng, who is also with the U-M Center for Human Growth and Development and School of Public Health. "We need to explore ways to target this drive to eat before children even turn three."