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In the first part of this series on childhood obesity we examined the recent trends and increasing prevalence that has been noted not only here in the US, but all over the world. We also learned about the medical differences between being overweight and obese. Finally, we learned how to calculate the Body Mass Index (BMI). For a quick review, please see last month's e-newsletter that is archived on Parkside's website. In this second part of the series we are going to tackle the causes of obesity and then in the final part to the series we will talk about the treatments.
Why are we becoming fatter? Well the answer doesn't lie with one single culprit, but rather multiple causes are to blame. While there is most certainly is a genetic component to obesity, the basic problem can be boiled down into an imbalance between energy intake and energy expenditure.
In recent years scientists have discovered several genes, hormones, and peptides that have a central role in the development of obesity. One of the latest discoveries is of a hormone called Leptin that controls the body's sense of starvation and fullness. Leptin resistance causes an individual to have a false sense of starvation which leads to overeating. Having overweight parents also sets kids up for a life of obesity. One study reports that if one parent is obese, then their child is 3x more likely for obesity in adulthood, and if both parents are obese the risk is 10x. In fact, the correlation of parental obesity to the development of obesity in their children is so strong that before the age of 3, parental obesity is a stronger predictor of obesity in their child than the child's weight.
So, if genetics isn't the whole story then what else is to blame? Unhealthy diets, increasing portion size, and decreased activity are three critical areas that are definitely adding fuel to the fire. Per capita soft drink consumption has increased 500% over the past 50 years! A study in 2001 showed that sugar sweetened drinks increase the BMI and frequency of obesity and a study in 2006 showed increased fruit juice intake to be associated with excess fat tissue gain. Of note: 1 can of soda/day = 15 lbs/year!
In addition, children today are eating a higher proportion of fast foods and processed foods rather than well balanced home cooked meals. Unhealthy meals that are high in fat and carbohydrates and low in protein contribute to a higher glycemic index that stimulates hunger in children and has been linked with central adiposity (aka fat middles).
Increased intake cannot be totally to blame though, as kids who are very active will burn off extra calories by running, playing, and participating in sports. Unfortunately that is not the case with the majority of American kids. Video games, TV watching, and computer time has replaced the time that kids once spent outside burning off calories. In the US, kids spend more than 25% of their waking hours watching TV. Moreover, 20% of US children 8-16 years of age reported 2 or fewer bouts of vigorous physical activity per week.
Increased weight is associated with bone and joint problems, early cardiovascular/heart disease, and development of diabetes. So what is a parent to do? We'll look into the possible solutions to this problem in the final part of this series.
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