The association between the healthy lifestyle index and MRI-derived body composition measurements in the UK Biobank study

A high healthy lifestyle index (HLI) score, which reflects an adequate amount of sleep, no alcohol consumption, no smoking, a moderate to high physical activity level, a high quality diet, and a normal body mass index (BMI), has been associated with reduced risk of morbidity and mortality. We examined the relationship between the HLI and measurements of adipose and lean tissue volumes measured using magnetic resonance imaging (MRI). We studied 33,002 participants in the UK Biobank study, aged 40-69 years at enrolment. Information on lifestyle components was obtained at the baseline examination (2006-2010), while MRI was performed at a later exam (2014-2020). A multilevel HLI score, constructed by assigning individual scores to each HLI component, was categorized into quartiles in multivariable linear regression analyses. Higher HLI levels were associated with lower levels of body composition parameters (visceral and subcutaneous adipose tissue, total adipose tissue, total lean tissue, muscle fat infiltration, abdominal fat ratio, weight to muscle ratio) in a dose-dependent manner (tests-for-trend p-value < 0.001 for all parameters). When BMI was excluded from the HLI score and included separately in the model, a direct association between HLI score and total lean tissue volume was observed. Higher HLI scores were associated with a better body composition profile.