U. TEXAS-AUSTIN / MICHIGAN STATE (US) — Adults with children gain significantly more weight over time than those without kids, according to new research.
The study, published in the journal Social Science and Medicine, examines how different life paths influence weight gain, including timing of first birth, transitioning into parenthood, and living with an adult child.
Researchers analyzed data from a national longitudinal survey that tracked changes in body mass index (BMI) levels (a ratio of height to weight) among 3,617 adults over a 15-year period. They found that by age 55, parents reach an average BMI in the obese zone (over 30) and peak at an average BMI of 31 by their mid to late 60s.
For adults without children, the average BMI only reaches the overweight zone (25 to 29) by age 55.
Both men and women who have their first child around age 26 to 27 gain the least weight over time. Weight gain was more rapid the further away from this age—either younger or older.
Parents who have children at a young age are more likely to be of low socioeconomic status, which is associated with increased risk for obesity, says Debra Umberson, professor of sociology at the University of Texas at Austin.
And those who have children later in life experience the effects of mid-life weight gain, which averages 3 to 4 pounds a year, along with the lifestyle constrictions of parenthood that further promote weight gain.
Fathers who live with their children gain even more weight than women, the study finds, suggesting that living with children alters the lifestyles of men even more than for women. Factors that influence weight gain for men include reduced exercise time and a decrease in substance abuse, such as smoking and heavy drinking.
“Parenthood imposes pressure for routine and new responsibilities such as staying sober and healthy to care for children,” Umberson says. “Given that smoking and heavy drinking are more prevalent among men, they are more likely to gain weight due to lifestyle behavioral changes.”
Although both parents progressively gain weight over time, women gain more while raising more than one child, possibly due to the biological effects of pregnancy added to the daily constraints and responsibilities of parenting.
The findings underscore how important it is for both men and women to maintain a healthy weight before and after they have children. This applies especially to those who are overweight or obese at the start of parenthood, says Umberson.
“Although the difference in annual rates of gain between parents and non-parents may not be noticeable in the short-run, these differences appear to become substantial over the course of adulthood.”
Researchers from Michigan State University and the University of Cincinnati collaborated on the study.
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