The development of obesity in schoolchildren may start as early as in the first months of our lives. (Photo: Colourbox)

Obesity starts in infancy

OPINION: Children who gain a lot of weight in the first months of their lives have a higher risk of developing obesity by school age. Perhaps it’s time we realise that obesity prevention should start at the time of birth.

The prevalence of obesity among Danish schoolchildren is higher than ever before and it also kicks in at an earlier age.

This is problematic because overweight children are more likely to be overweight as adults, leaving them having to fight their weight problems and numerous related health issues for the rest of their lives.

A new study from the Institute of Preventive Medicine at Bispebjerg Hospital in Copenhagen shows that significant weight gain already in the child’s first month of life increases the risk of obesity later in life.

Any weight gain increases the risk

In a study of more than 28,000 schoolchildren in Copenhagen, Professor Thorkild I. A. Sørensen and I have shown that high weight and weight gain, month on month in the first year of life, significantly increases the risk of childhood obesity.

The study is based on 28,340 schoolchildren in Copenhagen, born between 1959 and 1967, whose weight had been carefully measured and recorded in personal journals. 

For all 962 children who were obese at school age and a randomly selected control group of 1,417 children, data about their weight development as infants and at school age was recorded.

The kids were divided into the lightest third, the middle and the heaviest third at each age.

Unlike other similar studies, our study has shown that significant weight gain every month from the first month of life increases the risk equally and thus that no period is more important than others.

The results are clear

The study showed that children whose weight was in the upper third had a 1.3-1.7-fold greater risk of childhood obesity from birth to nine months of age, compared to children in the middle weight group.

Children whose weight was in the bottom third had about half the risk of obesity from two to nine months of age.

Children who moved up a group in weight had a 1.5-fold greater risk of obesity in childhood throughout infancy.

This study differs from the numerous studies that have shown that a great weight gain in the first year of life increases the risk of obesity later on in life.

In this one, the children were measured up to 22 times as infants, on average eight times, most frequently within the first four months.

The records also included data about whether the children were breastfed fully, partially or not at all, each time they were weighed.

The correlations were clear even after controlling for high birth weight, a short breastfeeding period and poor social conditions, all of which are known to cause obesity in children.

Infants shouldn’t be put on a diet

The findings suggest that the development of obesity in schoolchildren starts as early as in the first months of our lives, while most of us are still being breastfed and cannot even crawl.

This leads to the question of whether prevention of obesity should start as soon as the baby is born.

How much should we worry when infants weigh much more or gain much more weight than average?

This study does not say anything about the underlying mechanisms of the observed correlations or whether we can prevent major weight gain in infants, which is highly uncertain.

Therefore, we cannot advise parents to put their babies on a diet.

Further studies needed

There is a need for research into the factors that contribute to weight change in infants, the mechanisms that are in play and how to change weight gain in infants.

Since obesity is extremely difficult to prevent and treat, it’s possible that the greatest effect may be achieved if we start preventive interventions already during pregnancy or even before fertilisation takes place.

There is also a need for studies into whether the observed correlations can be demonstrated among today’s infants, who are breastfed significantly longer than those used in our study, and whose mothers smoke less but are more frequently overweight.

The study has been funded by the Danish Heart Foundation, Rosalie Petersen’s Foundation, Aase and Ejner Danielsen’s Foundation, the Danish PhD School of Molecular Metabolism, the University of Copenhagen, the Novo Nordisk Foundation, the Capital region of Denmark, the Danish Obesity Research Centre (DanORC), which is supported by the Danish Council for Strategic Research.


Read the Danish version of this article at

Translated by: Dann Vinther

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