Toronto, Sep 23 (IANS): Combining aerobics with resistance training may be the best exercise for obese teenagers, says a study.

"Adolescents who are overweight are typically advised to exercise more, but there is limited evidence on what type of exercise is best in order to lose fat," said co-researcher Ron Sigal from University of Calgary in Canada.

So to find out the best exercise, the researchers involved 304 overweight teenagers in Canada between 14-18 years.

All were given the same four weeks of diet counselling to promote healthy eating and weight loss before being randomly placed into four groups.

The first group performed resistance training involving weight machines and some free weights.

The second performed only aerobic exercise on treadmills, elliptical machines and stationary bikes.

The third underwent combined aerobic and resistance training while the last group did no exercise.

Among the youth who completed at least 70 percent of the study's exercise sessions, the percentage of body fat decreased "significantly more in those who did combined aerobic and resistance exercise than in those who only did aerobic exercise," co-principal researcher Glen Kenny from University of Ottawa noted.

"Waist circumference decreased close to seven centimetres in those randomized to combined aerobic plus resistance exercise, versus about four centimetres in those randomized to do just one type of exercise, with no change in those randomized to diet alone," Kenny noted.

The study appeared in the Journal of the American Medical Association (JAMA) Pediatrics.