Multifactorial Causes in Human Disorders: Obesity

"Food = joy, guilt, anger, pain, nurturing, friendship, hatred, the way you look and feel…

Food = everything you can imagine." (Susan Powter, The Columbia World of Quotations)

The holiday season is behind us and now we are being bombarded with advertisements for liquid dietary aids, health club memberships, "lose weight fast" pills, and ab rollers! It is a time to be reminded of the holiday drop-ins, office parties and family gatherings in which we may have eaten much more than our bodies required for sustenance. What an opportune time to introduce the concluding topic in our study of multifactorial inheritance…obesity!

Obesity is defined "as a body weight exceeding 20% of the upper limit of the normal range." Relying on this definition, it is believed that 20% of American adults are obese and that the numbers of obese children are also increasing. Although many believe that obesity results from lack of self-control, obesity is a true medical disorder concerned with the consumption of calories and the metabolism of those calories. It is a problem in which there is a lack of coordination between hunger and metabolism.

Studies of twins have provided evidence that both genes and environment play a role in obesity. Data from a recent research project involving 25,000 pairs of twins indicate that obesity may be 67% genetic and 33% environmental.

What are the genetic components in obesity? Recent research has revealed that several genes contribute to obesity. Presently, more than 40 genes are being studied, one on almost every chromosome. Continued genetic research will provide increased understanding of the causes of obesity and a better understanding of natural weight control that may lead to new treatments for the disorder.

Some of the most common environmental factors in obesity include physical activity, caloric intake and modern diets with the increased availability of high-fat content foods.

Although obesity is not a true disease, it is a known contributing risk factor in common diseases such as heart disease, stroke, type II diabetes and hypertension.