The results were disappointing. The study found no significant differences in the children’s body mass indexes at 12 or 24 months. Even when researchers restricted the analyses to the most adherent subjects, there were no significant differences over all in B.M.I.

The good news is that babies ate on their own: Parents can be reassured that coaxing their infants to eat more is not the only thing keeping them from malnutrition. The bad news is that more than 10 percent of the infants in the intervention group were overweight by 2 years of age . One of the most significant predictors of being overweight as an adult is being overweight as a child.

The best method of feeding babies has long been a subject of debate. An article published in 1948 in the same journal as this study, JAMA Pediatrics, reviewed the “literature on the so-called self-demand schedule of infant feeding” for prematurely born infants after they were discharged from the hospital. It noted that there was an increasing trend (in the 1940s!) toward allowing infants to regulate their own feeding. It noted the cyclical swings in thought between rigid regimentation of feedings and allowing too much freedom in a self-demand schedule.

It appears that some things have not changed.

The concerns expressed in the 1940s were very different from those of today, however. Then, people were focused on making sure babies got enough nutrition to grow and develop properly. Now, we are more worried about overconsumption and obesity.

It’s not clear whether humans are programmed to maintain a healthy weight on their own. Animals in the wild are subject to outside forces — the need to forage or kill, to compete, and to prepare for future shortages. Domesticated animals’ eating is regulated by us. Anyone who has owned a pet knows not to leave them alone with an open food supply, unless you want all that food to be gone.

This study supports the idea that, left to their own devices and supplied with more than enough food, babies will overeat. We still need to intervene. Nonetheless, there might be merit to giving infants more control over their eating: This study found that baby-led weaning resulted in children who were less fussy about what they ate and who seemed to enjoy their food more. Both of those things are good.

But if we want to find a larger solution to the issues of overweight American children and obesity, it seems we’re going to have to work harder. Babies aren’t going to solve the problem for us.