A Small Change Approach on Adiposity, Lean Mass, and Bone Mineral Density in Adults with Overweight and Obesity: A Randomized Controlled Trial

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Walc, Azalea
Obesity , Body Composition , Randomized Controlled Trial , Overweight , Adults , Bone Mineral Density , Lean Mass , Appendicular Lean Mass , Visceral Adipose Tissue , Dual X-Ray Absorptiometry , Imaging , Adipose Tissue , Lifestyle , Small Change Approach , Behavioural , Abdominal Obesity
Efforts to manage obesity through weight loss on a global scale have not been successful as most adults are unable to sustain the major changes in behaviour required to maintain weight loss long term. Many institutions now recognize that weight gain prevention by making small adjustments to energy intake (~100 kcal/day) and expenditure (~100kcal/day) represents a feasible strategy to manage obesity and related co-morbidities. The purpose of this thesis was to determine whether small changes in physical activity and diet could prevent adverse changes in body composition over two years in adults with overweight and obesity. Two-hundred and eighty-nine previously inactive participants were included in a secondary analysis of data derived from a three-year, single-centre, two-arm, longitudinal randomized controlled trial. Participants were randomized to a small change approach (SCA) (N=144) or usual care (UC) (N=145). The SCA participants were counselled to make small changes in diet and physical activity, while UC participants were asked to maintain their usual lifestyle. Adiposity, lean mass, and bone mineral density were measured by dual-x-ray absorptiometry. The study found that changes in total adiposity were significantly greater in SCA than UC at 6 and 12 months but did not remain significant at 24 months (mean change SCA [SE] -0.8 [0.4] vs. UC -0.7 [0.4] kg; difference 0.06, 95% confidence interval (CI) -1.1 to 1.2). Changes in visceral fat were significantly greater in SCA than UC at 6 and 12 months but did not remain significant at 24 months (-0.04 [0.03] vs. 0.02 [0.03] kg; difference 0.06, 95% CI -1.5 to 0.3). Changes in lean mass or bone mineral density were not significantly different between groups at any time points. A small preservation of appendicular lean mass was observed in the SCA compared to UC at 6, 12, and 24 months (0.0 [0.1] vs. -0.3 [0.1], difference 0.26, 95% CI 0.0 to 0.5). Overall, the findings of this thesis do not support the notion that the SCA is more effective than usual care for the prevention of gains in total and abdominal obesity or the preservation of lean mass and bone mineral density. Whether a SCA that incorporates frequent monitoring alone by health care professionals prevents increases in adiposity and preservations of lean mass in adults with overweight or obesity by comparison to usual care merits investigation.
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