## CRUNCHING THE WEIGHT GAIN NUMBERS: A MATHEMATICAL PERSPECTIVE ON OBESITY

I found this article from the New York Times (published 5/14/12) to be very interesting. It is an interview with Carson Chow, an applied mathematician from the National Institute of Diabetes and Digestive and Kidney Diseases, who used mathematical equations to analyze the etiology of the rise in obesity rates over the past 20-30 years. Through his applied mathematical analysis, Chow reports that his results indicate that a surplus of food supply, starting from the 1970s when the government began encouraging farmers to grow as much food as possible, is one culprit in rising obesity rates since then. He argues that in general, the amount of physical activity Americans do really hasn’t changed in the past 20-30 years. He further explains that with this surplus of food, came cheaper food prices and more marketing from food retailers and restaurants, which in turn encourages people to eat more. Since it is affordable and convenient, fast food is even more appealing to today’s busy American consumer.

Even more interesting, he found through mathematical analysis that the more overweight a person is, the easier it is for them to gain weight. Also Chow states, “huge variations in your daily food intake will not cause variations in weight, as long as your average food intake over a year is about the same. This is because a person’s body will respond slowly to the food intake.” This insight rings especially true for those “yo-yo dieters” or others who do dramatic diets that only produce temporary results. In addition, he touches on the idea that our body has a “set point” of body weight, which is a weight that our body tends to hover around despite variations in eating day to day. This set point can be “reset” though, both in a negative way (in the case of excessive intake over time resulting in overweight status that becomes the new set point), or a positive way (in the case of weight loss). However, it takes time for our body to reset, so when weight is lost, it must be maintained for a long time, 1-3 years, before that new point is set.

### To me, Chow’s findings demonstrate two things:

1. We have to be smarter food consumers and aware of what the human body actually needs in terms of nutrition to sustain normal growth and health. This includes listening to our hunger and satiety cues, knowing what is a healthy body weight for stature (i.e. normal BMI), and knowing how to put together healthy meals.
2. Weight management is a long term journey. It is a lifestyle change that really involves changes in all areas of life. It may mean cooking more at home, grocery shopping differently, adjusting the family budget, incorporating more physical activity into your day, and making food and health a priority in life. These are not easy changes, but if it is important to you or your family member to achieve weight management goals, meet with a registered dietitian to make a plan.