Prescription of Step Counts for Targeted Changes in Body Composition and Cardiometabolic Risk in Overweight/Obese Adults

The prevalence of overweight and obesity remains epidemic in the United States, with some of
the highest rates seen in older adults. While this phenomenon is certainly multifactorial, a good
deal of evidence suggests that insufficient physical activity (PA) contributes significantly. Pilot
data recently collected in our laboratory indicates a strong, inverse relationship between daily
step counts and body fatness and cardiometabolic risk (CMR) factors when step counts are
expressed relative to fat mass in young adults. This expression of PA may be especially
predictive of body composition because it is influenced by factors that influence appetite and
energy intake, energy expenditure, and the energy “reservoir” that is represented by body fat
stores, all three elements of the “settling point” model of body weight. The strength of this
relationship suggests that prescription of step counts that consider current body weight and
composition, and weight loss goal, may yield predictable changes in weight and CMR in adults
eating ad libitum. The long-term objective of this study is to quantify the relationship between
daily step counts and body composition in young, middle aged, and older adults who are
overweight/obese and develop a regression model that can be used to prescribe physical
activity (daily step counts) for achieving a specific target body weight and predictably improving
CMR risk for young, middle-aged, and older adult men and women over eight months while
eating ad libitum. To achieve this objective, we will undertake two specific aims: 1) quantify the
relationship between average steps·kg fat mass-1·day-1 and body composition/CMR profiles in
healthy, overweight, and obese adults 20-39 years, 40-59 years, 60-79 years, and 80-plus years
old, using inexpensive, widely available triaxial pedometers while eating ad libitum, and 2)
quantify the efficacy of employing targeted step counts expressed as steps·kg fat mass-1·day-1
using the model developed in Aim 1 for producing predictable improvements in body
composition and CMR factors in overweight and obese adults 20-39, 40-59, 60-79, and 80-plus
years old, over 8 months while eating ad libitum. This study will result in a regression model that
may significantly improve the way that PA is prescribed for weight management, with vast
clinical and public health implications.

Grant Number: 1R15AG081856-01A1
NIH Institute/Center: NIH
Principal Investigator: Robert Buresh