It’s no secret that breastfeeding is good for babies. But it may also reduce their risk of obesity later in life.

That’s according to a recent study by researchers at Mount Sinai’s Samuel Lunenfeld Research Institute, published Nov. 15, 2012, in the International Journal of Epidemiology.

Dr. Stephen Lye and his team followed children in western Australia from birth to age 14 and discovered that the length of time a baby is breastfed positively impacts the effects of the fat mass and obesity gene (FTO) in young adults. Specifically, breastfeeding can help reverse the effects of that gene variant if a child is exclusively breastfed for a three-month minimum.

The research team noted that girls required a minimum of three months breastfeeding, but boys appeared to need a longer breastfeeding period to have the full effect. They concluded that three-to-six months of exclusive breastfeeding would be the best approximation to affect the FTO gene.

Childhood obesity is a serious problem that may lead to the development of chronic diseases, which will be reflected in increased health care costs.

“This study is one of the first examples of early intervention in the fight against obesity,” says Lye, associate director of the Institute in Toronto. “Rather than trying to treat the symptoms later, we’re better off trying to prevent them in the first place.”

There has been a startling increase in the number of Canadian children with unhealthy weights since 1978, when, according to the Childhood Obesity Foundation of Canada, only 15 per cent of kids were overweight or obese. By 2007 that number had climbed to 29 per cent. Statistics Canada says that today almost one-third of Canadian kids, an estimated 1.6 million kids between the ages of five and 17, are overweight or obese. The foundation notes that most adolescents do not outgrow this problem and many continue to gain excess weight. If current trends continue, it predicts that by 2040 up to 70 per cent of adults age 40 will be overweight or obese.

The FTA gene comes in two flavours: good and bad, Lye explains. “We all have two copies of this gene, but 20 per cent of Caucasians have two copies of the bad variant. Under these circumstances, as an adult, on average you would have three kilos of fat mass more than you might otherwise.”

An estimated 70 per cent of Canadian children have at least one copy of the specific variant of the FTO gene responsible for increased BMI and obesity, and that increase can be seen as early as age six.

The first 2,000 days of life – roughly from conception to school age – a child undergoes massive development. “We’re understanding that while your genetic makeup controls the overall blueprint of how that development occurs, the environment interacts with it to put children on varying paths that impact their learning, health and social functioning,” Lye says.

“Our interest is in how the environment interacts with our genetic makeup, and this study shows that we can modify our genetic blueprints through positive environmental interventions.”

While there are other genes associated with massive obesity, they are very rare, Lye adds. “In genetic terms, this gene variant is actually a large contributor to obesity.

“This is one intervention and one gene, but it sets a proof of principal that if we understand more about how trajectories are settled during life, we can develop interventions that enhance how children optimize their full potential.”