People whose weight—or other metabolic measurements—fluctuates may be at a higher risk of heart attack, stroke, and death than people whose metabolic measurements stay the same, according to a new study in Circulation.
However, experts caution that the findings should not discourage people who are overweight or obese from trying to lose weight in the first place.
Cardiovascular disease risk factors
Research has shown that obesity and high blood pressure significantly increase the risk of heart attack, stroke, and death, according to Seung-Hwan Lee, a senior author of the study. However, there is less evidence about how cardiovascular disease risk changes when people's metabolic risk factors fluctuate.
For the study, researchers analyzed Korean National Health Insurance System data for over 6.7 million "healthy" people that had no medical history of diabetes, heart attacks, high blood pressure, or high cholesterol. During the study period, which lasted from 2005 to 2012, the participants underwent three health exams.
The researchers observed changes in participants' blood glucose levels, cholesterol concentration, blood pressure, and body mass index (BMI). The researchers recorded the variability of each factor on a zero-to-four-scale, with four indicated high variability in all four risk factors.
Weight loss not always an improvement?
Researchers found that participants with high variability in weight, blood pressure, cholesterol, and blood sugar levels during the study period were at a higher risk of heart attack, stroke, and death than participants with lower variability.
The researchers recorded nearly 55,000 deaths, more than 22,000 strokes, and more than 21,000 heart attacks during the study's follow-up period.
The found individuals with the most variability in their weight, blood pressure, cholesterol and blood sugar levels were about 2.3 times more likely to die during the study period and 40% more likely to have a heart attack or stroke, when compared with those with little fluctuation in those factors.
The risk of these negative outcomes increased with the participants' variability score, regardless of whether these changes resulted in "improvement," like weight loss, or "setback," like weight gain.
Consistency is key
To reduce the risk of heart attack, stroke, and death, a patient's metabolic risk factor should stay within a healthy range throughout their lifetime, according to Claude Bouchard from the Pennington Biomedical Research Center, who was not involved in the study.
This means that patients should avoid the yo-yo diet, or "repeated weight loss and weight regain," according to Marie-Pierre St-Onge, a researcher at Columbia University Irving Medical Center, who was not involved in the study.
"Weight gain poses a stress on the body which can increase the risk of heart attacks or strokes," St-Onge said. "The ultimate goal is not to maintain overweight or obesity but rather to maintain normal weight throughout life."
But, Bouchard said that, with the exception of elderly patients, the study results should not deter people who are overweight or obese from trying to achieve a healthier weight. "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," Bouchard said. "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" (Rapaport, Reuters, 10/2; Kim et al., Circulation, 10/2).
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