Women often experience weight gain during menopause because it dramatically cuts their desire to exercise, according to a new study.
The researchers sought to determine the factors leading to women's weight gain during menopause, and how it might be avoided.
"So many women get confused when they start to gain weight during menopause, because their eating habits haven't changed," said Dr Amanda Sainsbury-Salis from Sydney's Garvan Institute of Medical Research.
"What the research shows clearly is that menopause causes a dramatic and sudden reduction in physical activity levels. Just prior to menopause, women halve their amount of activity compared to pre-menopause levels.
"So one reason women gain weight in menopause is because of a reduction in energy expenditure. Combine this with unchanged eating habits and weight gain is almost inevitable," she added.
The research also suggests that weight gain is directly related to the lack of oestrogen, which has dramatic effects on signals the brain sends to the body.
However, further studies are on to see what causes these effects and whether or not they continue long-term.
Researchers suggested that increasing the levels of physical activity can help prevent weight gain.
"A lot of women ask whether they can actively counteract that tendency. In fact, it's been shown that women who maintain or increase their level of physical activity during menopause tend to come out the other end without gaining weight."