A comprehensive review by the International Menopause Society has found that going through the menopause does not cause a woman to gain weight. However, the hormonal changes at the menopause are associated with a change in the the way that fat is distributed, leading to more belly (abdominal) fat.

To mark World Menopause Day (Oct. 18), the International Menopause Society has developed a state-of-the-science review on weight gain at the menopause. This report is published in the peer-reviewed journal, Climacteric.

Being overweight or obese is a major worry for many women, and through midlife, women tend to gain on average around 0.5 kg per year (around 1lb per year). This can have significant consequences, as being overweight or obese is associated with a range of conditions including depression, hypertension, cardiovascular disease and diabetes. Globally, around 1.5 billion adults are overweight, and of these around 300 million women are obese. Obesity rates have doubled since 1980, especially in Western countries. There are a variety of reasons for the increase, not only lifestyle reasons. In general, more women than men are obese, and fluctuations in sex hormones have been proposed as being implicated in the weight gain.

The review group considered the evidence on why women gain weight around the menopause. They found that absolute weight gain is determined by non hormonal factors, rather than the menopause itself.

The key finding was that the way fat is deposited changes at the menopause; studies indicate that this is due to the drop in estrogen levels at menopause. Irrespective as to whether women do or do not gain weight at midlife, after the menopause, women experience a shift in their fat stores to their abdomen .

According to review leader, Professor Susan Davis (Monash University, Melbourne, Australia): "It is a myth that the menopause causes a woman to gain weight. It's really just a consequence of environmental factors and aging which cause that. But there is no doubt that the new spare tyre many women complain of after menopause is real, and not a consequence of any changes they have made. Rather this is the body's response to the fall in estrogen at menopause: a shift of fat storage from the hips to the waist."

The review notes that increased abdominal fat increases the risk of future metabolic disease, such as diabetes and heart disease, in postmenopausal women. It also noted that, contrary to popular opinion, estrogen therapy (HRT) does not cause women to put on weight. There is good evidence that HRT can prevent abdominal fat increasing after menopause.

The IMS is calling for women to be more aware of the problems associated with excess weight, and to take early steps to ensure that they don't gain excess weight after the menopause.

Professor Davis continued: "What this translates to in real terms is that women going through the menopause should begin to try to control their weight before it becomes a problem, so if you have not been looking after yourself before the menopause, you should certainly start to do so when it arrives. This means for all women being thoughtful about what you eat and for many, being more active every day. Estrogen therapy (HRT) can also help. But each woman is different, so at the menopause, it is important to discuss your health with your doctor."

IMS President, Tobie de Villiers (Cape Town, South Africa), said: "Weight gain is a major risk factor for a variety of diseases, including diabetes and cardiovascular disease. Heart disease is by far the number one killer of postmenopausal women, and this risk is increased by excess weight. Women need to be aware of this, especially at the menopause when estrogen levels drop. A woman may need to adjust her lifestyle to ensure a healthier life after the menopause. In fact, I would say that a woman should consider using the menopause as a marker, a reason to review her overall health, with her doctor, so that she can take her own decisions on how her life moves forward."