The relationship between physical activity, appetite and energy intake in older adults: A systematic review.

Ageing often causes a reduction in appetite and energy intake in older adults which can result in malnutrition. Current guidelines for older adults suggest increasing physical activity to enhance appetite. However, it is unclear if there is evidence to support this advice. This aim of this review is to assess if appetite and energy intake is changed in older adults that undertake acute or regular physical activity (measured from cross sectional and intervention studies). Databases SPORTDiscus, CINAHL, MEDLINE were searched for studies between 1970 and 2017 using search terms related to ageing, physical activity (including exercise), energy and appetite. Studies included contained adults over 60 years, including acute, cross-sectional and intervention (longitudinal) studies. Of 34 full-text articles assessed, 8 were included. The Cochrane Collaboration's tool was used for assessing risk of bias. No acute studies were found. Of the cross-sectional studies, one study suggested that individuals who undertake habitual physical activity had an increased energy intake and none of the studies found differences in appetite ratings. Energy intakes increased in the intervention studies, though not always sufficiently to maintain energy balance. One study showed that ability to correctly compensate for previous energy intake was better in those that undertake habitual physical activity. The limited number of studies, wide range of data collection methodologies, time-scales and interventions mean that definitive outcomes are difficult to identify. At this stage advice to increase acute or habitual physical activity as a mean to increase appetite is not supported by sufficient evidence.