A Metabolic–Epidemiological Microsimulation Model to Estimate the Changes in Energy Intake and Physical Activity Necessary to Meet the Healthy People 2020 Obesity Objective

摘要

Objectives. We combined a metabolic and an epidemiological model of obesity to estimate changes in calorie intake and physical activity necessary to achieve the Healthy People 2020 objective of reducing adult obesity prevalence from 33.9% to 30.5%. Methods. We used the National Health and Nutrition Examination Survey (1999–2010) to construct and validate a microsimulation model of the US population aged 10 years and older, for 2010 to 2020. Results. Obesity prevalence is expected to shift toward older adults, and disparities are expected to widen between White, higher-income groups and minority, lower-income groups if recent calorie consumption and expenditure trends continue into the future. Although a less than 10% reduction in daily calorie intake or increase in physical activity would in theory achieve the Healthy People 2020 objective, no single population-level intervention is likely to achieve the target alone, and individual weight-loss attempts are even more unlikely to achieve the target. Conclusions. Changes in calorie intake and physical activity portend rising inequalities in obesity prevalence. These changes require multiple simultaneous population interventions. The US federal government’s Healthy People 2020 objectives include reducing obesity prevalence among adults aged 20 years and older from 33.9% in 2005 to 2008 to 30.5%. 1 It is unclear how much of a reduction in calorie intake or increase in physical activity would be necessary to achieve this objective, because of real metabolic constraints on people’s ability to lose weight. It is also unclear whether the reduction in calorie intake or increase in physical activity necessary to reach this objective is consistent across age, racial/ethnic, and income groups. The latter question has important implications for targeting interventions to population groups with greatest need. In the past, mathematical models incorporating either epidemiological or metabolic data have been used to try to answer these questions. Epidemiological models forecast future trends in obesity by extending trends in body mass index (BMI) into the future; metabolic models project how individuals’ actions affect their body weight, taking into account the biochemistry of intake and expenditure. 2–6 To understand what population-level changes in calorie intake and physical activity are necessary to achieve the Healthy People 2020 objectives, we created a combined epidemiological–metabolic model.