Could a 30 minute workout help you lose as much weight and body mass as exercising for an hour?
A study by the University of Copenhagen suggests this may be the case for men who are healthy but slightly overweight.
Research published in the American Journal of Physiology followed 60 danish men who wanted to get in shape.
Men who exercised 30 minutes a day lost an average of eight pounds over three months, while those who worked out for an hour lost about two pounds less.
Researchers aren't sure why the men who exercised longer didn't lose more weight.