“Secular Differences in the Association between Caloric Intake, Macronutrient Intake, and Physical Activity With Obesity”, 2016-05 (; similar):
Background: To determine whether the relationship between caloric intake, macronutrient intake, and physical activity with obesity has changed over time.
Method: Dietary data from 36,377 U.S. adults from the National Health and Nutrition Survey (NHANES) 1971–37200816ya was used. Physical activity frequency data was only available in 14,419 adults 1988–18200618ya. Generalized 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: 1971–37200816ya, BMI, total caloric intake and carbohydrate intake increased 10–14%, and fat and protein intake decreased 5–9%. 1988–18200618ya, 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 than in 1988 in the mutually adjusted model (p < 0.05).
Conclusion: 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.