Despite the benefits of exercise, fewer than a third of the 6 000 women questioned were active, the journal Menopause reports.

London – Millions of women are not taking enough exercise because they are afraid of being ‘judged’, a report says.

They worry they will be ridiculed for being sweaty, out of breath or struggling at the back when jogging or at the gym.

Some women have taken to running in secret on treadmills installed in sheds in their back garden because they are too ashamed to do it in public.

A report by MPs on the Commons’ Health Select Committee also highlights how girls as young as ten shun physical education classes because they worry about their body image.

Figures show that just over two thirds of women, 68 percent, do not take the recommended level of exercise of two and a half hours over the course of a week.

This is much higher than the 56 percent of men who do not do this weekly amount.

Experts have warned that a lack of exercise is as harmful as tobacco and contributes to up to one in six deaths in the UK.

Tory MP Dr Sarah Wollaston, chairman of the committee, said: ‘It is unacceptable that this gender gap has been ignored for so long. We need to be out there ensuring that girls can access the type of sport they want to take part in.’

Labour MP Barbara Keeley said girls aged ten, 11 and 12 were dropping out of games lessons because they were worried about showing ‘puppy fat’.

One woman interviewed by the committee was told by her male GP she was too fat to do the London Marathon even though she had run about 29km the week previously.

Julie Creffield, a campaigner who encourages women to exercise, said she was determined to ‘prove him wrong’ and finished the event in 2013.

Creffield, 36, a mother who works as a motivational speaker, said many women were afraid to join running clubs or attend gym classes because they didn’t want to be the one ‘struggling at the back.’

This is particularly true if they are overweight or have gained a few kilos after having children.

She told the MPs: ‘I have women who tell me they run on a treadmill in their shed because they just don’t want to be seen in public, and that’s part of the problem. Because we don’t see many overweight women exercising in public, other women don’t think exercise is for them.’

Daily Mail