This is a double-blinded randomized controlled trial, to evaluate the effectiveness of daily supplementation of 3.2 g CLA on body fat reduction and lipid profile in overweight or obese Chinese adults, during a lifestyle counselling-based weight loss.

This will be a parallel randomized, double-blinded, placebo-controlled trial. Sixty-six overweight or obese men and women aged from 18 to 45 years with elevated body fat percentage, who also meet our inclusion and exclusion criteria, will be randomly assigned to: the treatment group, daily supplementation of 3.2 g CLA (Cis-9, trans-11 isomers and trans-10, cis-12 isomers) plus lifestyle counselling weight loss program; or the control group, daily supplementation of sunflower oil. The intervention will include a 3-day run-in phase and 12-week interventional phase. At baseline and the end of the intervention, physical examination including questionnaires, anthropometric measurement, body composition by Dual Energy X-ray Absorptiometry (DXA), biological sample collection will be undertaken. During the invention, regular lifestyle counselling sessions will be delivered, and detailed record will be tracked for all participants to monitor and improve the adherence and safety.

Inclusion Criteria:

1) Body fat percentage ≥ 20% for men, Body fat percentage ≥ 30% for women ; 2) aged from 18 to 45 years old.

Exclusion Criteria:

1. Pregnancy or lactation;
2. Abnormal liver or kidney function indicated by physical examination within 6 months;
3. Gastrointestinal problems that affect the complying with the procedure;
4. Sever cardiovascular disease;
5. Active cancer;
6. Mental diseases, epilepsy or using anti-depression drugs;
7. Using medicine that affect body weight;
8. Participating in other scientific studies within 3 months before the study.