Aerobic exercises for at least 150 minutes a week is important for reducing waist and body fat, researchers have said after reviewing 116 studies involving nearly 7,000 overweight and obese adults.

While the highest reductions in body weight and waist circumference were seen with aerobic training for 300 minutes a week, best improvements in body fat percentage were seen with 150 minutes a week. The findings were published in The Journal of the American Medical Association (JAMA) Network Open.

Aerobic, or cardiorespiratory, exercises, including running and cycling, get one's heart rate up and improve oxygen delivery to muscles and organs.

Researchers, including those at the Imperial College, London, said that current recommendations around how long one should do aerobic training for losing weight meaningfully are based on individual studies and meta-analyses, or reviews of previously published literature, were lacking.

For their analysis, the team looked at randomised clinical trials -- a type of experiment comparing how effective an intervention is for a given condition.

The studies involved a duration of at least eight weeks of supervised aerobic training in adults with body mass index exceeding 25 (for Western countries) or 23 (Asian).

The researchers found that while 30 minutes of aerobic exercise a week helped adults experience "modest" reductions in body weight, waist circumference and body fat, 150 minutes and above helped with "clinically important reductions".

"Aerobic exercise training at least 150 minutes per week at moderate intensity or higher may be needed to achieve clinically important reductions in waist circumference and measures of body fat," the authors wrote.

Greatest reduction in body fat percentage -- of over two per cent -- was seen at 150 minutes of aerobic training per week.

Further, reduction of over four kilograms in body weight and four to five centimetres in waist circumference were seen for 300 minutes of aerobic exercises a week.

However, the greatest improvement in body fat percentage was related to 150 minutes per week of aerobic training.

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