NEW YORK - CONTRARY to expectations, the higher a woman's percentage of body fat at menopause, the more likely she is to experience symptoms such as hot flashes and night sweats, a new study shows.

Such so-called 'vasomotor symptoms' had previously been thought to be less common in heavier women at menopause, because body fat can convert male hormones into oestrogen, Dr Rebecca C. Thurston of the University of Pittsburgh School of Medicine and colleagues note. Fatter women would therefore have a reserve source of oestrogen that could shield them from these symptoms.

However, there is mounting evidence that heavier women may actually experience more vasomotor symptoms with menopause, the researchers add in their report in the American Journal of Epidemiology.

To better understand the relationship between body fat and menopausal symptoms, Dr Thurston and her team looked at 1,776 women going through menopause. Fifty-nine per cent reported having vasomotor symptoms.

As body fat increased, the researchers found, so did the likelihood that a woman would have hot flashes and night sweats.

The findings contradict the hypothesis that being fatter protects women from vasomotor symptoms, they write. Instead, they suggest, it is possible that excess fat makes it more difficult for the body to dissipate heat.

Based on the findings, Dr Thurston and her colleagues add, weight loss - especially loss of fat - may help women going through menopause to reduce hot flashes and night sweats.