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It's important to maintain a healthy BMI, but if you're a normal weight woman caught in cycles of yo-yo dieting, there may be an unexpected risk.
Healthy weight women who periodically crash diet to lose 10 pounds or more had more than three times the risk of dying suddenly from a heart attack, compared to those whose weight remains stable, according to a new study presented Tuesday at the American Heart Association’s annual meeting. While previous research has found no link between yo-yo dieting and cancer, this is the first study to track the connection between weight cycling and sudden cardiac death.
"Our study showed that more than four times weight cycling increases the risk," said Dr. Somwail Rasla, a researcher from Brown University’s Memorial Hospital of Rhode Island.
For the new study, the Brown University researchers followed 158,063 post-menopausal women, ages 50-79, for just over 11 years. At the beginning of the study, the women were asked how their weights had varied during their lifetimes. They were then placed into one of four categories: stable weight, steady weight gain, maintained weight loss, and weight cycling — meaning their weight had gone up and down over time.
At the end of the study, the researchers looked for any connections between weight cycling and death from heart attack. While yo-yo dieting didn’t seem to have an impact on women who were overweight or obese, it did have a big effect on those who were “normal weight.”
Normal weight yo-yo dieters were 3.5 times as likely to die suddenly — within an hour — from a heart attack compared to normal weight women whose weight had been stable throughout their lives. They were also 60 percent more likely to die in the hospital after having a heart attack.
The research didn’t try to explain how yo-yo dieting might increase your risk of death from a heart attack. But Rasla has some theories.
Stressful to the body
As we gain weight, cardiac risk factors, such as high blood pressure and glucose levels, tend to increase. The theory is that, over time, the body mitigates this somewhat by making adjustments, Rasla said. When we yo-yo diet, the body doesn’t have time to make those adjustments.
Beyond that, Rasla says, yo-yo dieting may have an impact on DNA.
“We did a trial on a mouse model and found that mice exposed to weight cycling behaviors ended up with damage to their DNA,” he said.
The fact that yo-yo dieting had an impact only in thinner women “is surprising,” says Dana Hunnes, senior dietician at the University of California, Los Angeles, Medical Center and adjunct assistant professor at UCLA’s Fielding School of Public Health.
Lose weight safely
Because Rasla’s study is observational, it can’t prove that yo-yo dieting causes heart attacks, Hunnes said. And it's possible that normal weight women who lose and regain weight may have underlying illnesses which may be linked to heart disease risk, said Naveed Sattar, professor of Metabolic Medicine, University of Glascow.
It shouldn't stop anyone from trying to drop pounds, even if weight gain may recur.
Hunnes has advice for women who want to lose those extra 10 pounds safely:
- Very gradually reduce calorie intake
- Up activity by 200-300 calories per day
This would result in a 1/2-pound weight loss per week.
Yes, it will take 20 weeks to lose those 10 pounds, but, maintaining it will be significantly easier, and safer for your heart.