Women with partners put on more weight

After adjusting for other variables,the 10-year weight gain for an average 140-pound woman was 20 pounds if she had a baby and a partner,15 if she had a partner but no baby,and only 11 pounds if she was childless with no partner. The number of women with a baby but no partner was too small to draw statistically significant conclusions.

There is no reason to believe that having a partner causes metabolic changes,so the weight gain among childless women with partners was almost surely caused by altered behaviour. Moreover,there was a steady weight gain among all women over the 10 years of the study.

This does not explain the still larger weight gain in women who became pregnant.

The lead author,Annette J Dobson,a professor of biostatistics at the University of Queensland in Australia,suggested that physiological changes might be at work.

Womens bodies may adjust to the increased weight associated with having a baby, Dobson said. There may be a metabolic adjustment that goes on when women are pregnant that is hard to reverse. This would be more consistent with our findings than any other explanation.

The study covered over 6,000 Australian women over a 10-year period ending in 2006.

At the start,the women ranged in age from 18 to 23. Each woman periodically completed a survey with over 300 questions about weight and height,age,level of education,physical activity,smoking status,alcohol consumption,medications used and a wide range of other health and health care issues.

By the end of the study,published in The American Journal of Preventive Medicine,over half the women had college degrees,about three-quarters had partners and half had had at least one baby. Almost all of the weight gain happened

with the first baby; subsequent births had little effect.

Also by the end of the study period,there were fewer smokers and risky drinkers than at the beginning,more women who exercised less and a larger proportion without paid employment.

But even after adjusting for all of these factors and more,the differences in weight gain among women with and without babies,and among women with and without partners,remained.

Despite the studys limitations weight was self-reported,for example,and the sample size diminished over time

because people dropped out other experts found the

results valuable.

Its interesting and brings out some important points, said Maureen A Murtaugh,an associate professor of epidemiology at the University of Utah who has published widely on weight gain in women. Perhaps,she suggested,a more active social life may help explain why women with partners gain more weight.

Think of going to a restaurant, Murtaugh said. They serve a 6-foot man the same amount as they serve me,even though Im 5 feet 5 inches and 60 pounds lighter.

The study included only women,but the researchers cited one earlier study that showed an increase in obesity among men who had children,adding further evidence that social and behavioural factors are part of the explanation.

Dobson said the finding of weight gain among all the women,with families or without,was troubling.

This is a general health concern, she said. Getting married or moving in with a partner and having a baby are events that trigger even further weight gain.

From a prevention point of view,one can look at these as particular times when women need to be especially careful.