Women in their mid 40s and 50s gain an average 1.5 pounds a year and because many women experience menopausal symptoms during this time, it is widely believed (particularly by women themselves) this increase in weight is due to hormonal changes. I probably hear this explanation for weight gain several times a week in clinic. But whilst it may be convenient to blame the menopause for mid-life weight gain, it’s a myth.
In the Study of Women’s Health Across the Nation (SWAN) project, over 3000 ethnically diverse women across the USA were followed for a period of three years. As expected, there was a steady increase in the average weight and waist circumference of the women over this period, but there was no association whatever with menopausal status. Other studies have also failed to find any relationship between the menopause and weight gain, independently of age. In addition, although some women avoid taking hormone replacement therapy (HRT) precisely because they think it will make them fat, there is in fact no good evidence to show that HRT increases weight.
Some women do experience a change in body shape as they enter the menopause, because as oestrogen levels decline, there is a re-distribution of body fat from the hips, thighs and buttocks to the waist area, hence “middle-age spread”. But this change in fat distribution is not invariably associated with weight gain.
The fact is that women (and men) get fatter as they get older, because they become increasingly inactive. As physical activity declines, the amount of lean (muscle) mass also declines. In most women aged 40-59 years, there is an approximately 20% reduction in lean mass. This is important because muscle burns three times as many calories as fat, even when people are at rest. This explains why, as we lose muscle we become less able to burn calories and we gain weight.
The message is clear. It is important to bear in mind the relationship between physical activity and obesity, and if you want to stay slim well into old age, you need to preserve your muscle mass by staying active. Additionally, physical activity really does seem to be an effective alternative to HRT. In the SWAN project referred to earlier, women who maintained high levels of physical activity throughout middle age had less body fat, smaller waists and less weight gain than those who were inactive – irrespective of their menopausal status. So the mantra is: a brisk mile a day keeps menopausal fat at bay.
Dr David Ashton
7th September 2011
A version of this article appeared in Reader’s Digest magazine.