Scientists have uncovered many contributors to the child-obesity epidemic. The latest culprit? The baby bottle. A new study published in the journal Pediatrics says children who are bottle-fed beyond age 2 are more likely than others to be fat at age 5. Here, a brief guide to the findings:

How was the study conducted?
Researchers analyzed the habits and weight of 6,750 children — all born in 2001 — in an Ohio database. About one in five were still using the bottle at age 2.

So how much does bottle-feeding increase the chances of obesity?
Substantially. Twenty-three percent of kids who had been bottle-fed past age 2 were obese at age 5. Just 16 percent of those who stopped drinking from the bottle by age 2 were severely overweight by age 5.

Why such a difference?
Bottles are typically filled with fattening whole milk. One 8-ounce bottle has up to 150 calories, which amounts to 12 percent of the daily dietary needs of a healthy 2-year-old.

Are there other health risks?
Yes. Bottle-fed kids were also prone to tooth decay and other problems — especially if their bottles were sometimes filled with sugary juice.

So when's the best time to wean kids from the bottle?
Pediatricians encourage parents to start getting their kids off the bottle at age 1. And 18 months is really the outer limit when making the switch to cups. "Can the child drink appropriately from a cup?" asks dietician Keith Ayoob of the Albert Einstein College of Medicine. "If they can, there's no more need for the bottle."

Sources: Parentdish, CBS News, U.S. News, ABC News