If you want to lose weight after the excesses of the Christmas period, you may be better off heading for the bedroom rather than the gym.
Making love really does count as significant exercise, scientists say.
They have found that an hour of romance between the sheets burns almost as many calories as a 30-minute jog and so should be taken into account when drawing up a fitness plan.
Men expend 120 calories during half an hour of sex and women use up 90, say researchers from the University of Quebec in Canada.
That is just under half the amount they would burn in a 30-minute jog. For brief periods during sex, some men used more energy than they did while on the treadmill.
The study, Energy Expenditure During Sexual Activity In Young Healthy Couples, found that, on average, men burned 4.2 calories a minute during sex compared to 9.2 on the treadmill. Women burned 3.1 calories a minute during sex and 7.1 jogging.