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Do you think that children with supposedly unhealthy eating behaviour develop a higher BMI? It's likely the other way around. A high BMI comes first.

Children gain weight before they start eating unhealthy food

Some children resort to food as a comfort or eat more for other reasons. But the link between predicted obesity-promoting eating behaviour and high BMI may not be what you think.

Big children eat more than other children. Research has shown that overweight children are more likely to use food as a comfort or eat until their plate is empty, even though they may be full.

But which comes first, eating behaviour or high body-mass index (BMI)?

How can we promote good eating habits in children?

  • Facilitate pleasant mealtimes – adults are responsible for the atmosphere around the table. Remember that food is more than nutrition and is about spending time together over a meal.
  • Let children decide how much to eat. You can decide what and when they should eat (e.g. "You can choose between these three vegetables, and we'll eat dinner at five."). Children who are overweight and who may have difficulty feeling full may need a limit set for how much to eat (e.g. "I understand that you want more, but your body only needs two slices for supper." or "In our family we eat one portion for dinner.").
  • If the child has difficulty controlling their own food intake, explore with the child how the body signals that it is full, and how the bodily sensation of hunger differs from emotions like boredom and restlessness.
  • It takes a while from when we start to eat until the brain registers that we are satiated. Practise eating more slowly. Put your fork down between each mouthful, stop and ask yourself along the way: Am I full?
  • If your child needs help regulating food intake, strive to use indirect forms of control. For example: Make 'smart' foods easily accessible and less healthy options inaccessible (if there aren’t any biscuits in the cupboard, we can’t eat biscuits). Stay one step ahead – such as setting out two slices of bread or agreeing ahead of time on how much ice cream the child may have – rather than stopping the child midway through eating (Don't say: "Now you've had more than enough already!").
  • Avoid using food as a comfort. Offer your lap, warm words and a hug instead.
  • Avoid using food as a reward. Instead give positive attention in the form of a smile, kind words or a 'thumbs up' if the child does something you want to reinforce.
  • Avoid using labels on the child like "You’re a big eater," or "You’re so picky." It only adds insult to injury.
  • Encourage children to taste the food, but do not force them to eat. It is okay to spit something out. Try to make tasting a game – examine the food’s consistency, smell, colour and shape and be curious with the child.

A research group at NTNU has investigated this question in almost 1,000 children. Their study is based on participant data collected every other year from age 6 through age 14.

“We looked at the connection between predicted obesity-promoting eating behaviour in children and an increase in BMI,” says Oda Bjørklund, a PhD candidate and psychologist at NTNU’s Department of Psychology.

Their findings were somewhat surprising.

Bigger children need more food

“We’ve found that an increase in what we previously called obesity-promoting eating behaviours, such as emotional overeating, doesn’t lead to increased BMI,” says Silje Steinsbekk, a professor in the Department of Psychology.

But researchers are finding a link in the opposite direction.

“The more children’s BMI increases, the more likely they may resort to eating to deal with difficult emotions or because food is available, even though they might not be hungry,” says Steinsbekk.

So the weight gain comes first, and eating habits follow.

“Very simply put, this finding probably reflects that large bodies need more food,” says Steinsbekk.

At the same time, she emphasises that the reason some people develop large bodies is multifaceted and involves a complex interplay between heredity and the environment.

The NTNU researchers have only investigated how changes in eating habits are related to changes in BMI in school age children through to adolescence.

Studies of younger children and infants have found that eating behaviours characterised by the child eating for reasons other than hunger, such as food being available or comfort eating, increase BMI over time.

Prevention important

Obesity early in life tends to follow us into adulthood. This can have multiple well-known effects on our health.

“Even though we haven’t found that these eating behaviours lead to an increase in BMI from the age of 6, we still encourage parents to promote good eating habits in children,” says Bjørklund.

Bjørklund also treats eating disorders in child and adolescent psychiatry (BUP). She points out that eating behaviour is not only related to physical health.

“We didn’t look at what the children were eating, but how they related to food and eating,” she said.

Advice on wise food choices can be found on the Norwegian diet tool Kostverktøyet (link in Norwegian).

Trondheim Early Secure Study

The researchers used figures from the Trondheim Early Secure Study (TESS), which has followed almost 1,000 children every two years since they were 4 years old. The participants are now 18 years old, and the eighth survey is underway.

In this study, the research group used data from the participants at five different times, when they were 6, 8, 10, 12 and 14 years old. The Trondheim Early Secure Study has provided data for a number of studies on children’s development and health.


Bjørklund et al. The prospective relation between eating behaviors and BMI from middle childhood to adolescence: A 5-wave community study, Preventive Medicine Reports, vol. 27, 2022. DOI: 10.1016/j.pmedr.2022.101795

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