| "The authors examined the dietary data of 36,400 Americans between 1971 and 2008 and the physical activity data of 14,419 people between 1988 and 2006. They grouped the data sets together by the amount of food and activity, age, and BMI." ^ The previous paragraph to the one I quoted above. Methods Dietary data from 36,377 U.S. adults from the National Health and Nutrition Survey (NHANES) between 1971 and 2008 was used. Physical activity frequency data was only available in 14,419 adults between 1988 and 2006. Generalised linear models were used to examine if the association between total caloric intake, percent dietary macronutrient intake and physical activity with body mass index (BMI) was different over time. Results Between 1971 and 2008, BMI, total caloric intake and carbohydrate intake increased 10–14%, and fat and protein intake decreased 5–9%. Between 1988 and 2006, frequency of leisure time physical activity increased 47–120%. However, for a given amount of caloric intake, macronutrient intake or leisure time physical activity, the predicted BMI was up to 2.3 kg/m2 higher in 2006 that in 1988 in the mutually adjusted model (P < 0.05). Conclusions Factors other than diet and physical activity may be contributing to the increase in BMI over time. Further research is necessary to identify these factors and to determine the mechanisms through which they affect body weight. ^ Copypasta from the referenced medical study: http://www.sciencedirect.com/science/article/pii/S1871403X15... What I think I'm seeing is a confusion with the conclusions. What they found was: 1988: Daily calories = x, leisure play = y, observed BMI = z
2006: Daily calories = x, leisure play = (1.47 to 2.2)*y, observed BMI = 2.3 + z
The same amount of calories today results in greater BMI.Either the average person's body composition today has a greater percentage of muscle and that's throwing things off, or something else is up with how we live that's making us heavier. But, we see other studies out in the wild that suggest average fitness is lower, which leads me to think the former solution might not be the case. |