US researchers from Johns Hopkins University have shown for the first time that giving women a combination of testosterone and the female sex hormone oestrogen can help them stay healthier.

As women go through the menopause there is a natural increase in fat.

Women live for an average of 30 years after the menopause, during which time their body fat is 20% higher than in women of child-bearing age.

Research has also found that women lose nearly 4% of muscle mass within the first three years of menopause.

Many women take oestrogens after menopause to combat symptoms like hot flushes and depression, but levels of male hormones, or androgens, which are present in low levels in women, also drop as women age.

However, the impact of androgen decline has been far less studied than that of oestrogen.

In the four-month study of 40 post-menopausal women aged 48 and 65 conducted at Johns Hopkins, fat tissue in the women receiving oestrogen-androgen therapy decreased from 6% to 4%, while lean muscle increased from 2% to 6%.

Women receiving only oestrogen did not have any body composition changes.

All of the women in the study had previously been on oestrogen replacement therapy for three months or longer.

Healthier and more active

Therapy could help women stay active into old age

Lead researcher Dr Adrian Dobs said: "By adding small doses of androgen with oestrogen to a woman's body, we may be able to reduce her body fat while also increasing her lean muscle.

"Proper diet, regular exercise and hormone replacement therapy, such as oestrogen and androgen, may help keep menopausal women's bodies strong and agile, enabling them to lead healthier and more active lives."

Scientists were concerned that the use of testosterone could also lead to a reduction in HDL, or good cholesterol which helps to keep the circulatory system healthy, but this was countered by a parallel decline in triglycerides which are associated with heart disease.

Dr Dobs said: "We think the overall effect on cardiovascular disease may be minimal."

Previous research has found that oestrogen-androgen therapy may also help improve bone density in post-menopausal women.

However, there may be some drawbacks.

As with traditional oestrogen therapy, the hormone combination also causes symptoms such as breast tenderness, headaches and nausea.

And, on its own, oestrogen replacement is thought to raise the risk of breast and uterine cancer.