Moderators of Resistance Training Effects in Overweight and Obese Adults: A Systematic Review and Meta-analysis

Abstract

Purpose: This study aimed to analyze whether the effects of resistance exercise on whole-body fat and lean mass are moderated by exercise dosage (i.e., duration, volume, and intensity), age, body mass index, baseline values, assessment methods, and prescription of aerobic exercise and caloric restriction in overweight/obese adults. Methods: A systematic search was undertaken in 11 databases from inception to December 2020, with an updated search undertaken in April 2022. Eligible randomized controlled trials examined the effects of resistance-based exercise programs on whole-body fat mass and lean mass in adults who were overweight or obese. Meta-analysis was undertaken with a random-effects model. Associations between mean differences and potential moderators were tested by meta-regression models. Results: Sixty-seven articles describing 65 trials (n = 2537) were included. Resistance-based exercise programs resulted in a significant change of −1.6 kg (95% confidence interval [CI] = −1.9 to −1.3 kg, P < 0.001) in whole-body fat mass and +0.8 kg (95% CI = 0.6 to 0.9 kg, P < 0.001) in lean mass. Male participants experienced greater effects than females (P < 0.001), whereas those presenting with higher levels of fat mass at baseline experienced greater reductions in this outcome (P = 0.084). For lean mass, younger adults experienced greater improvements compared with older participants (P = 0.009), whereas programs comprising resistance exercise and caloric restriction resulted in significant reductions in lean mass (P = 0.035). Resistance exercise dosage or prescription of aerobic exercise was not associated with change in these outcomes. Conclusions: Resistance-based programs improve body composition regardless of the resistance exercise dosage or aerobic component prescribed in adults who are overweight or obese. In addition, subgroups based on demographic characteristics, baseline levels, and presence of caloric restriction may present with more favorable responses in body composition.

Moderators of Resistance Training Effects in Healthy Young Women: A Systematic Review and Meta-analysis

“…Regarding the meta-regression results, we did not observe significant associations between resistance training prescription characteristics and changes in body fat percentage. This result partially agrees with previous studies undertaken in overweight/obese adults (46) and healthy adults (81). Therefore, for women with relatively lower BMI or body fat percentage levels, a moderate-intensity resistance training program of ∼72 weekly sets may be necessary to achieve greater reductions in body fat percentage because of greater improvements in lean mass/muscle hypertrophy.…”

“…For example, we included only nonobese young healthy women, whereas Hagstrom et al (27) included young and middle-aged women regardless of body mass. We previously observed that resistance-based exercise programs result in smaller adaptations in middle-aged compared with young adults (46,48). In addition, we used a three-level metaanalysis, whereas a two-level meta-analysis was used by Hagstrom et al (27).…”

“…Regarding fat mass, we observed a modest reduction (i.e., SMD # 0.5) in body fat percentage after resistance training programs but not whole-body fat mass. Our inclusion criteria may partially explain this result because only nonobese healthy women were included (median BMI of 22.2 kg•m 22 ; median body fat percentage of 26.5%), and higher baseline levels of whole-body fat mass are associated with greater reductions after resistance-based exercise programs (46). Also, the very low-to-low GRADE indicates that the extent of benefit may be limited and not certain in young women.…”

Impacto de los diferentes tipos de entrenamiento físico sobre la composición corporal en mujeres adultas con obesidad: una revisión bibliográfica

“…Por lo tanto, los hallazgos de esta revisión sistemática podrían romper con el pensamiento de que el entrenamiento aeróbico tradicional es el principal medio para perder peso [76], especialmente para la población con sobrepeso y obesidad. Después de todo, el entrenamiento de fuerza puede aumentar la masa magra corporal y la masa muscular además de reducir el %GC [77,78,79,80], mejorando así la composición corporal. Por tal motivo, este hallazgo brinda un fuerte apoyo al entrenamiento de fuerza como una futura forma efectiva de combatir la obesidad, perder grasa y ganar músculo.…”

What are the most effective exercise, physical activity and dietary interventions to improve body composition in women diagnosed with or at high‐risk of breast cancer? A systematic review and network meta‐analysis

“…Nevertheless, our exploratory pairwise meta-analysis indicates that aerobic exercise and/or dietary interventions could be useful to significantly reduce fat mass and body weight; however, this is accompanied by a reduction in lean mass in women high risk of breast cancer. Previous exercise and dietary recommendations for adults who are overweight or obese may be useful to improve lean mass and fat mass in this specific subgroup[149][150][151][152] and potentially reduce the risk for future treatment/surgical complications. Second, most studies had a high risk of bias, and this likely affected the precision, magnitude, and certainty of the evidence.…”