Prospective association between body composition, physical activity and energy intake in young adults.
OBJECTIVE
Despite considerable research on the association between physical activity (PA) and body composition, there remains limited information on the directionality of the relationship. The present study examined the prospective associations among objectively measured PA, energy intake (EI) and body composition.


METHODS
A convenience sample of 430 adults (49% male) between 21 and 35 years of age was followed over 1 year with repeated measurements taken every 3 months. BMI (kg/m(2)) and percent body fat (%BF) were calculated based on anthropometric measurements and dual energy X-ray absorptiometry. A multi-sensor device was worn over a period of 10 days to estimate total daily energy expenditure and time spent in different intensities. EI was calculated based on change in body composition and total daily energy expenditure.


RESULTS
A total of 379 participants provided valid data. On average, participants experienced a significant weight gain of 1.2±4.3 kg during the 12-month observation period, which was associated with an increase in %BF (0.8±3.2 %). Average time spent in moderate-to-vigorous PA (MVPA) decreased significantly, whereas EI remained constant. Optimal linear mixed models, adjusting for age and sex, showed an inverse effect of MVPA on BMI and %BF, whereas EI only directly affected BMI (P<0.001). There was also a significant inverse effect of BMI and %BF on MVPA (P<0.001).


CONCLUSIONS
Results of this study indicate an inverse reciprocal association between MVPA and measures of adiposity. Thus, primary preventive actions are warranted to avoid excess weight gain, which may result in a vicious cycle of weight gain and low PA.
Department of Exercise Science, University of South Carolina, Arnold School of Public Health, Columbia, SC, USA.
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Drenowatz
Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA.
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Cai
Department of Exercise Science, University of South Carolina, Arnold School of Public Health, Columbia, SC, USA.|School of Public Health, West Virginia University, Morgantown, VA, USA.
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Hand
Department of Population and Public Health Sciences, Pennington Biomedical Research Center, Baton Rouge, LA, USA.
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Katzmarzyk
Department of Kinesiology, Iowa State University, Ames, IA, USA.
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Shook
Department of Exercise Science, University of South Carolina, Arnold School of Public Health, Columbia, SC, USA.|Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA.
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Blair
D015502:Absorptiometry, Photon; D050154:Adiposity; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D002149:Energy Intake; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011446:Prospective Studies; D057185:Sedentary Behavior; D055815:Young Adult