Acute simulated weight gain might not increase the energy cost of walking in adolescents with obesity

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Summary Introduction This work aims at evaluating the adaptations of the energy cost of walking (Cw) to simulated weight gain at different walking speeds in adolescents with obesity. Methods Substrate use and Cw were evaluated during a graded walking exercise (4 × 5min at 0.75, 1, 1.25, 1.5 m.s−1) performed under three randomized body weight conditions (BW‐conditions): (i) at the adolescents' body weight (BW + 0%) or with a simulated weight gain of (ii) 5%(BW + 5%) and (iii) 10%(BW + 10%), in 18 adolescents with obesity (14.2 ± 1.4 years, BMI:33.86 ± 2.55 kg.m‐2). Body composition was assessed by absorptiometry and perceived exertion rated after every walking speed stage. Results EE in absolute or relative to BW and FFM was different between BW‐conditions (p = 0.017, 0.006 and 0.007, respectively) being lower on BW + 5% than BW + 10%. Gross Cw (absolute, relative to BW and fat‐free mass) showed overall speed (p < 0.001) and BW‐conditions effects, being lower on BW + 5% compared with BW + 10% (p < 0.001). Net Cw (absolute, relative to BW and fat‐free mass) showed a significant speed effect (<0.001) but no BW‐conditions nor interaction effect. Conclusion While EE and Cw have been shown to decrease in response to weight loss, potentially as a way to save stored energy and limit further weight loss, inverse adaptations do not seem to occur with increased acute simulated weight gain in weight stable adolescents with obesity.