Phase angle and body composition: A scoping review.

The aim of the study was to map evidence on the association between phase angle (PhA) and body composition in populations healthy and clinical populations). A systematic search for information regarding the topic was conducted in nine electronic databases (CINAHL, LILACS, PubMed, SciELO, Scopus, SPORTDiscus, Science Direct, MEDLINE and Web of Science) between October and November 2021. Studies with different designs, which allowed extracting information about the relationship between PhA and body composition (body cell mass [BCM], muscle tissue, bone mineral content, lean mass, total fat mass, visceral fat, and lean soft tissue mass [LSTM]) were included. Of the total of 11,913 initially identified studies, 59 were included after reading titles, abstracts, full texts and references. Most studies (40.67%; n = 24) presented data from Brazilian samples. With regard to the design of studies, 15 (25.42%) had longitudinal design. The age group of studies was wide, with studies involved 3-year-old children and 88-year-old adults. Body fat mass was evaluated by 31 studies (52.54%) in which 11 observed inverse relationships, nine studies showed direct relationships and 11 observed no relationship. Regarding lean mass, muscle mass, and fat-free mass components, most studies observed direct relationship with PhA (n = 37; 86.04%). It could be concluded that the phase angle was directly associated with lean mass and muscle mass in different age groups (children, adolescents, adults and older adults) and in people with different health diagnoses (HIV, cancer, hemodialysis, sarcopenia and without the diagnosis of diseases). Regarding body fat and the other investigated components, there is not enough evidence to establish the direction of associations.