Chubby babies and tubby toddlers are at risk of becoming overweight children and obese adults, so parents, doctors and other caregivers need to help prevent infants and young children from getting fat, the National Academy of Sciences concluded Thursday.

Mothers, fathers, day-care workers, preschool employees and others should limit how much time kids spend parked in front of the television, watching videos and using other electronic gadgets, make sure they get enough exercise and sleep, and ensure they eat the right foods, the academy’s Institute of Medicine recommends in a new report.

“A lot of conventional thinking has been that a big baby is a healthy baby,” said Leann Birch, director of the Center for Childhood Obesity Research at Pennsylvania State University, who chaired the 14-member panel that issued the 140-page report. “What’s happened over the past decade or so is that the evidence has been building that early overweight or early rapid weight gain places kids at risk for later obesity.”

About 10 percent of U.S. children between infancy and age 2 are overweight, according to the report. Among kids ages 2 to 5, the situation is worse — more than 20 percent are too heavy, a rate that has doubled since the 1980s, the report says.

Research indicates that many parents do not realize infants and young children who are overweight are at risk of obesity, which increases the risk for a host of health problems, including diabetes, heart disease and cancer, according to the report.

As a result, doctors should measure infants’ weight and length and calculate toddlers’ body mass index (BMI) as a standard part of routine well-child visits, the report recommends. That will help them identify children at risk for obesity, alert parents and recommend steps they can take.

“It’s not always easy to tell. There are chubby babies who are doing fine, but there are babies who are so chubby they are at risk,” Birch said in a telephone interview. “Just looking at them doesn’t allow you to make that distinction.”

Lack of adequate sleep may be an important factor causing children to become overweight, according to the report. Overall, infants and children, especially those younger than 3, appear to be getting less sleep over the past two decades, the report says. Babies up to age 2 should get nine to 12 hours of sleep every 24 hours, and those ages 2 to 5 should get 11 to 13 hours.

Regulators should require day-care centers to take steps to ensure that children get adequate sleep and pediatricians should counsel parents about how much sleep their kids should be getting and how to improve their sleeping patterns, according to the report.

Inadequate sleep may contribute to weight gain by causing metabolic changes, as well as by giving kids more time to snack.

“With reduced sleep you would have snacking patterns and more food intake,” said Debra Haire-Joshu, director of the obesity prevention and policy research center at Washington University, who was a member of the panel.

In addition, day-care centers and preschools should be required to follow dietary guidelines and to take steps to encourage children to be physically active throughout the day, the report recommends.

Kids should get at least 15 minutes of physically active play every hour. Infants should be allowed to move freely, with appropriate supervision. Cribs, car seats and highchairs should only be used for their intended purposes, and strollers, swings and bouncing chairs should be used judiciously, the report recommends.

Children ages 2 to 5 should use television, computers, mobile devices and other electronic devices for less than two hours a day, according to the panel. Day-care centers should restrict time in front of a screen to 30 minutes in half-day programs and one hour in full-day programs, the report recommends.

Health-care providers and others should also encourage more women to breast-feed, which has been shown to reduce the risk for becoming overweight, according to the report. Only 13 percent of mothers breast-feed exclusively for six months after birth.

Although the report was welcomed by many obesity and childhood development experts, some questioned many of the report’s conclusions.

“It is well established in the relevant literature that the vast majority of so-called ‘fat’ kids do not become fat adults. Similarly, most ‘fat’ adults were not fat kids,” said Patrick Basham, an adjunct scholar at the Cato Institute. “So we need to calm down, rather than panic, about our children’s weight.”

Basham said he worried about the impact of focusing on weight so early in life.

“The focus from a very young age on the need for a child to ‘not be fat’ serves only to increase the already-vast number of young people suffering from eating disorders,” he wrote in an e-mail.