Myopenia or muscle wasting due to ageing, chronic disease, and various medical interventions has been associated with increased mortality, morbidity, and poorer physical function. Attempts through nutrient and exercise interventions have been made to prevent this deterioration. In addition, while a measure of lean body mass (LBM) is associated with health outcomes, LBM function may be a better prognostic tool. Long-chain omega-3 fatty acids (LCn-3s) are nutrients that may mitigate LBM losses in noncancer populations. The purpose of this review is to determine whether LCn-3s have a role in LBM sparing in noncancer populations, to establish a minimum dose and duration of LCn-3s that will result in LBM change, and to summarise the potential effects of LCn-3s on LBM function when combined with an anabolic stimulus. Overall, in noncancer populations, LCn-3s have limited utility in sparing LBM during energy balance, energy restriction, or in conjunction with aerobic exercise. Further investigations are required to determine the appropriate dose and duration of LCn-3s for optimal LBM function. Finally, compelling evidence exists for LCn-3s in conjunction with an anabolic stimulus to improve LBM function and quality. Functionality of LBM tissue is an important outcome for population health, and LCn-3s show some promise, albeit pending further study.