Historical Declines in Housework Contribute to Obesity in Women

March 05, 2013

COLUMBIA, SC — A new study adds yet more evidence that the decline in physical activity is contributing to the increase in obesity in the US [1]. This study, however, is bound to cause some controversy, as researchers found the increase in obesity in women is tied to a reduction in the amount of housework they currently do compared with days gone by.

Published in PLoS One, the study showed that women are doing far less housework in 2010 than they were in 1965, and this has led to a net reduction in energy expenditure of 360 calories per day. In 1965, women cooked, cleaned, and did laundry, among other household work, an average of 26 hours per week, while in 2010 the amount of time spent doing the same work declined to 13 hours per week.

The researchers,led by Dr Edward Archer (University of South Carolina, Columbia), stress, however, that they are not advocating that women--or men--do more housework. Instead, the results should get individuals to think about how much energy they are expending throughout the day and also get policymakers to think about addressing the "calories-out" aspect of obesity and the energy equation.

"Our results show that we have engineered physical activity out of the workplace, out of the home, and out of our daily commute," Archer told heartwire , "and this has severe and dramatic consequences for our health. We need to find a way of reintegrating that activity to make up for the decrement in calories expended."

The study is an extension of a study conducted by Dr Timothy Church (Pennington Biomedical Research Center, Baton Rouge, LA) in 2011, which showed a decline in daily physical activity in the workplace. The reduction in physical activity translated into a reduction in energy expenditure of approximately 140 calories in men and 110 to 120 calories in women. In men, the reduction in physical activity at work explained most of the variance in obesity over a 40-year period, but the correlation was less strong in women. Based on these data, Archer hypothesized that 40 to 50 years ago, most households were one-income homes, with women staying home doing housework.

With this in mind, researchers used data from the American Heritage Time Use Study (AHTUS) to get a better representation of time-specific activities of women in the past. They were able to obtain historical data on the amount of time spent doing unpaid housework and family care in 1965. The time allotted for housework declined from 25.7 hours per week in 1965 to 13.3 hours per week in 2010, with unemployed women reducing the amount of housework by 16.6 hours per week and employed women by 6.7 hours per week. Household management energy expenditure declined 42% for unemployed women, down from 6004 calories expended per week in 1965 to 3486 calories expended per week in 2010, a reduction of 2518 calories.

"We found that nonemployed women are spending about 360 calories less per day doing physical activity, and if we look at obesity as calories in and calories out, this is a huge number of calories," Archer told heartwire . "It's about 15% of their total daily energy expenditure. We spend hundreds of millions of dollars studying diet and nutrition, which is the energy in, but we spend almost no money on the energy-expenditure portion of the equation. The most modifiable factor in the energy-balance equation is physical activity."

In the study, researchers also observed that the amount of time women spent watching television, and later using the computer, doubled from eight hours per week in 1965 to 16 hours per week in 2010.

Archer said that guidelines recommend 30 minutes per day of physical activity, which is enough to reduce the risk of cardiovascular disease. However, this will not have much of an effect on weight and body fat. Instead, the Institute of Medicine recommends at least an hour per day of moderate activity for weight maintenance. Treating obesity means at least 90 minutes or two hours of daily moderate exercise. To heartwire , Archer said that while patients complain that they do not have enough time for such programs, television is the biggest source of wasted time.

"The number-one recommendation is to turn off the television and replace that time with walking and lifting weights," he said.

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