Are your brother or sister to blame for your weight?

The stat line on obesity reads like a horror story. Obesity rates have doubled since 1980, 40 million children under the age of 5 are overweight or obese, being overweight kills more people annually than being underweight, and the worst part is it is all preventable. Plenty of research has been done to show that the a diets high in fast foods, sugar and larger portion sizes are all associated with the increasing obesity rates seen across the world and in particular in North America. It is also well known that inactivity and sedentary life styles are just as, if not more, problematic as poor diets (1, 2). In fact a recent study (that I may review in the coming weeks) suggests that physical inactivity is more a more important determinant of obesity than poor diet. It has been known for some time that all these factors contribute to obesity but who should shoulder the blame? Certainly there is plenty of blame to be shared between the food industry, advertisers, parents, schools and the government however a new study suggests that the health of someone’s older or younger siblings may play a determining role in whether someone becomes overweight or obese.

The research, published in the American Journal of Preventative Medicine took a sample of over 10,000 American households to determine the relationship between childhood body weight and the health of their siblings. To no surprise, in single child households, if at least one parent was obese the child was twice as likely to be obese compared to if neither of the parents were obese. However, what the researchers saw was that in families with two children, having an obese younger sibling or obese older sibling meant that the child was 5.5 times more likely to be obese when compared to a child with no obese siblings. Interestingly, the weight of the siblings is more important than the weight of the parents in determining the child’s weight. Why? Well it is known that the family household environment plays a strong role in the health of children and these results could just be an indicator of the environment within the house. For example, it would make sense that if one child is overweight because of the diet he/she is fed than the other children, who are exposed to the same diet, are likely to also be overweight. What we could be seeing here is how a poor diet or exercise routine implemented by parents could affect the health of everyone in the family. On the other hand, it is possible that these results indicate some behavior among the siblings that reinforce the behaviors that lead to obesity. It has been shown that siblings tend to eat similarly and also tend to have similar levels of exercise or physical activity. It is likely then that siblings have a greater influence on the health of each other than we realize. Whatever the reason for the results, the meaning behind them is the same; the environment that children are raised in plays a big role in the determination of their overall health. A healthy diet and active lifestyle is necessary for every child to be healthy and maintain a healthy body weight and instituting proper lifestyle choices will benefit everyone. Since it appears from the study that siblings have a vital role in determining children’s weight, it would be vital to ensure that each child in the household maintains a healthy weight and that everyone plays an encouraging role in keeping each other active and healthy. Treatment of childhood obesity would benefit from education about the role family structure plays in eating and exercise habits.

A couple things should be noted about this study. First, the information in it was gathered by survey and therefore is liable to be biased to some degree. People probably tend to under estimate the amount to which they may be overweight and may be in denial about their children being overweight. The study is also associative in nature therefore you cannot draw the conclusion that the reason kids are obese is because their siblings are obese. However, the study does provide some useful insight into the importance of a healthy environment and healthy family in the overall health of children (See previous article “DNA damage from bad parenting?”. In final, put down the chips, get off the couch and find something physically active to do that your whole family can enjoy. You can end obesity as easily as that!


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