By Lisa Rapaport

(Reuters Health) – People with fluctuations in their weight, blood pressure, cholesterol and blood sugar may be more likely to have heart attacks and strokes than those with stable measurements, a Korean study suggests.

Obesity and consistently elevated blood pressure, cholesterol and blood sugar have long been linked to an increased risk of having, and dying from, heart attacks and strokes, senior study author Dr. Seung-Hwan Lee of the Catholic University of Korea in Seoul said by email. But less is known about what happens when people have fluctuations in these so-called metabolic risk factors over time, especially if they haven’t been diagnosed with conditions like diabetes or high blood pressure, Lee said.

For the current study, Lee and colleagues examined data collected by the Korean National Health Insurance System from 2005 to 2012 on more than 6.7 million people without a history of heart attacks, diabetes, high blood pressure or high cholesterol. All of these people had at least three health exams during the study period, and researchers followed half of them for more than 5.5 years.

During follow-up, there were almost 55,000 deaths, more than 22,000 strokes and more than 21,000 heart attacks.

Compared to people with little variation in their weight, blood pressure, cholesterol and blood sugar levels, individuals with the most fluctuation in these measurements were about 2.3 times more likely to die during the study period and more than 40 percent more likely to have a heart attack or stroke.

“For patients, it would be prudent to avoid repeated weight loss and weight regain for optimal cardiovascular health,” said Marie-Pierre St-Onge, a researcher at Columbia University Irving Medical Center in New York City.

People who are overweight or obese should not, however, be deterred from trying to shed excess pounds by concerns that weight fluctuations might harm their health, St-Onge, who wasn’t involved in the study, said by email. Instead, they should set achievable weight loss goals that would enable them to maintain a lower weight over time and avoid yo-yo dieting.

“Weight gain poses a stress on the body which can increase the risk of heart attacks or strokes,” St-Onge added. “The ultimate goal is not to maintain overweight or obesity but rather to maintain normal weight throughout life.”

In the study, researchers looked at variability in metabolic risk factors of more than 5 percent. They examined improvements like weight loss and worsening measurements like weight gain separately.

Large fluctuations in metabolic risk factors – whether improvements or setbacks – were associated with a higher risk of death during the study, researchers report in Circulation.

The study wasn’t a controlled experiment designed to prove whether or how variation in metabolic risk factors might directly cause heart attacks, strokes or premature death. Another limitation is the possibility that results in Korean patients might not reflect what would happen elsewhere or with people from other racial or ethnic backgrounds.

Patients should also look differently at weight than they do at other metabolic risk factors, said Claude Bouchard of the Pennington Biomedical Research Center in Baton Rouge, Louisiana.

Blood pressure, cholesterol and blood sugar levels should remain stable, in a healthy range, for optimal cardiovascular health, Bouchard, who wasn’t involved in the study, said by email.

But with the exception of elderly patients, overweight or obese people should still try to lose weight even when it means their size fluctuates a lot over time, Bouchard advised.

“There is no convincing evidence that it’s detrimental to health for obese people to attempt to lose weight even when they relapse and try again and again,” Bouchard said. “The bulk of the evidence suggests that reaching a lower body weight, even when it is only for a limited number of months, has positive effects on the metabolic profile for most people.”

SOURCE: Circulation, online October 1, 2018.