Moderation Effect of Handgrip Strength on the Associations of Obesity and Metabolic Syndrome With Fatty Liver in Adolescents

Abstract

Introduction/background: This study aimed to evaluate the effect of handgrip strength on the associations of body mass index and metabolic syndrome with an indicator of nonalcoholic fatty liver disease in adolescents. Methodology: In data of 1690 adolescents aged 10–18 yr from the Korea National Health and Nutrition Examination Survey 2014–2016, alanine amino-transferase levels, age, sex, bodyweight-, sex-, and age-standardized handgrip strength, age- and sex-specific body mass index Z-scores, and metabolic syndrome severity scores were assessed. Nonalcoholic fatty liver disease was defined based on alanine amino-transferase levels (boys ≥52U/L, girls ≥44U/L) in adolescents who were overweight. Moderation analysis via the PROCESS procedure was performed. Results: The prevalence of nonalcoholic fatty liver disease was 1.5% among all adolescents and 6.7% among those who were overweight. In all adolescents and adolescents who were overweight, age- and sex-specific body mass index Z-scores and metabolic syndrome scores had positive associations with nonalcoholic fatty liver disease after adjusting for bodyweight-, sex-, and age-standardized handgrip strength. Bodyweight-, sex-, and age-standardized handgrip strength had an inverse association with nonalcoholic fatty liver disease after adjusting for metabolic syndrome scores, and this association became nonsignificant after adjusting for age- and sex-specific body mass index Z-scores. There were positive associations between age- and sex-specific body mass index Z-scores and alanine amino-transferase levels when bodyweight-, sex-, and age-standardized handgrip strength values were ≤−0.13 in overweight adolescents and ≤0.74 in all adolescents, whereas these associations were nonsignificant or negative above those cut-off values. These cut-off values of bodyweight-, sex-, and age-standardized handgrip strength for the relationship between metabolic syndrome scores and alanine amino-transferase levels were −0.15 in overweight adolescents and 0.55 in all adolescents. Conclusions: A higher bodyweight-, sex-, and age-standardized handgrip strength may attenuate the risk of obesity and metabolic syndrome for an indicator of nonalcoholic fatty liver disease in adolescents.