Abstract: Conjugated linoleic acid (CLA) is widely used in the diet of non-exercising and exercising populations due to its role in promoting fat decomposition and improving physical performance. CLA enhances the expression of uncoupling protein-1 (UCP-1) and increases the activity of carnitine-palmoil-transferase-1 (CPT-1) by interacting with the peroxisome proliferators-activated receptors (PPAR), which accelerates lipid metabolism and finally changes body composition. At present, the debate on the effects of CLA on reducing fat and its side effects is still going on. This paper divides the target population of CLA into non-exercise training and exercise training groups, and compares the fat-reducing effects of CLA in the groups. Results show that the effects of CLA supplementation on human lipid metabolism and body composition are affected by race, gender, age, health status, physical fitness, diet structure, dosage and time of consumption. Among rodents that are closely related to humans, CLA reduces body fat in mice most effectively, and this effect can be enhanced by combining it with exercise. Considering that CLA supplementation may cause side effects, the consumption of foods rich in CLA may be a better choice for obesity control.

Key words: conjugated linoleic acid; lipid metabolism; body composition; molecular mechanism; exercise training