What is making America fat? It’s not what you think

America fat
The obesity epidemic in the USA is a serious health issue – people weigh more and are less healthy than ever before, leading to conditions such as Type 2 diabetes, heart disease and stroke. What is behind this general rise in obesity? Fast food? Gluten? Soda?

Turns out the culprit is even closer to home.

A study from Stanford University collected 20 years’ worth of data from the US National Health and Nutrition Examination Survey (NHANES) and discovered that the rise in obesity is not due to overeating, but to our increasingly sedentary lifestyles.

Uri Ladabaum, Associate Professor of Medicine in Stanford University School of Medicine, led the study, which focused on waistline obesity, physical activity and calorie intake in American adults up to 2010. NHANES data from the past 20 years showed that caloric intake has remained fairly steady, while leisure time physical activity has decreased drastically. This has lead to a steady increase in Body Mass Index (BMI).

Alarmingly, the greatest decrease in leisure-time exercise has been in women: while in 1994 19.1% of adult American women reported doing no exercise, this number has grown almost threefold to 51.3% in 2010. Men fare slightly better, but the numbers are still worrying: 11.4% of men admitted to doing no exercise in 1994, and by 2010 a whopping 43.5% had gone completely sedentary.

The results of this lack of exercise are plain to see: the average body mass in the USA increased about 0.37% per year during this period, with the greatest increase occurring to young women. Professor Ladabaum summarized their findings: "At the population level, we found a significant association between the level of leisure-time physical activity, but not daily caloric intake, and the increases in both BMI and waist circumference."

While the study did not delve in detail on the types of food consumed during the time studied, they did calculate the total daily consumption of calories, fat, carbs and protein, and they discovered that these had not changed significantly in 20 years.

Prof.Ladabaum clarified: "Our findings do not support the popular notion that the increase of obesity in the United States can be attributed primarily to sustained increase over time in the average daily caloric intake of Americans." He also drew attention to some alarming disparities regarding which groups had become more sedentary or had seen the greatest BMI increases, pointing out that the study’s "analyses highlight troublesome trends in younger adults, in women, and in abdominal obesity prevalence, as well as persistent racial/ethnic disparities."

Buck the trend and add a little exercise to your day: walk the dog, get off the bus one station sooner, climb a flight or two of stairs. Your body will thank you.