Crystal Karges celebrated her youngest daughter’s fifth birthday last month with a gooey chocolate cake covered in white frosting and rainbow sprinkles. The next morning, she served her five children the leftover slices at breakfast alongside fruit, eggs, sausage and milk. 

Ms. Karges is among parents, dietitians and doctors who advocate giving children more freedom over what they eat including, at times, high-sugar, high-fat and highly processed foods. They said the approach helps children develop healthy dietary habits and protect against disordered eating—or dysfunctional eating behaviors—which affects more than 20% of children globally, according to a recent meta-analysis in the journal JAMA Pediatrics. 

“We are trying to control our kids when in reality, they need autonomy,” Ms. Karges, who is a dietitian in San Diego, said. 

Ms. Karges and her peers are pushing back against guidance from some pediatricians and public-health officials that they say is too prescriptive and risks fostering harmful eating habits. The Centers for Disease Control and Prevention recommends a diet rich in vegetables, fruit, whole grains and protein, while limiting the calories children get from solid fats, added sugars and sodium. The American Academy of Pediatrics in January recommended that physicians offer weight-loss drugs to children with obesity, which is linked to many health problems in early life and adulthood.

“The reality is that weight is highly associated with a number of co-morbidities. Weight loss can improve them,” said Sarah Hampl, a lead author of the guidelines and a pediatrician at Children’s Mercy Kansas City in Missouri.  

About a fifth of children in the U.S. are obese, according to the CDC. The rate of increase in body-mass index, a screening tool doctors use to measure excess fat, more than doubled among children during the pandemic. Many children aren’t eating enough vegetables and fruit and have sugary drinks regularly, according to the CDC. Diets high in sugar and trans-and-saturated fats contribute to obesity, research has shown, which is linked to cardiovascular problems, diabetes and other conditions. 

“Sometimes kids need some external help in saying, ‘OK, you know, that’s probably enough,’” said Claudia Fox, a pediatrician and co-director of the Center for Pediatric Obesity Medicine at the University of Minnesota Medical School.

But restricting appetizing foods has been linked in some studies to weight gain and higher body-mass index in children. Some researchers think children with restrictive diets don’t develop the ability to recognize hunger and satiety—the state of feeling full—which is important to regulating food intake. They often eat in the absence of hunger, similar to overweight adults, because those foods become a forbidden temptation. 

A diet rich in fruits and vegetables is recommended by the Centers for Disease Control and Prevention.

Photo: Asa Featherstone, IV for The Wall Street Journal

Proponents of more-permissive eating said parents shouldn’t consider weight when deciding what to feed their children. “It’s incredibly traumatic for a child to be given the information that because of their body size or the way they look, or their weight, they can’t be trusted with food,” said Sumner Brooks,

a dietitian and co-author of “How to Raise an Intuitive Eater: Raising the Next Generation with Food and Body Confidence.” Dieting can predispose children to obesity and eating disorders, studies have shown.

Diana Rice, a dietitian in Oklahoma City, said she counsels parents on how to encourage their children to follow their own tastes and hunger signals to fullness. Eventually, even sweets-loving children will tire of junk food and gravitate toward fruits and vegetables, she said. 

“We have to trust children to meet their biological needs,” Ms. Rice said. 

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That doesn’t mean parents should give into their children’s every whim, she said. Parents should take the lead in planning, preparing and serving meals but incorporate children’s preferences, she said. Ms. Rice said she tells clients to allow children to eat as much as they want at a meal, whether it is a little or a lot. She encourages parents with children fixated on sweets to serve dessert alongside main meals rather than afterward. 

“Pack cookies in their lunch box. Serve ice cream after dinner. Make it a regular part of their life so kids learn to self-regulate around those foods,” she said. 

Ms. Rice said she often serves her daughters, ages 5 and 7, snack plates of caramel corn, cheese, sugar snap peas and Doritos. At breakfast, she puts out a Hershey’s Kiss with her children’s toast, sunflower seed butter and fruit. When they are having dessert, they can have as much as they want, she said, and they usually stop at a small serving of chocolate or ice cream. 

“They need to have that trust that the food is going to be available,” she said.

Write to Sarah Toy at sarah.toy@wsj.com