Body Weight Swings Linked to Increased Mortality Risk

Nancy A. Melville

December 05, 2018

A continuous pattern of weight gain and loss, or weight cycling, is associated with an increased risk of premature death; however, the weight fluctuations in fact show some benefits in warding off diabetes among people who are obese, according to new research.

"This study shows that weight cycling can heighten a person's risk of death," says lead author Hak C. Jang, MD, PhD, a professor at Seoul National University College of Medicine and Seoul National University Bundang Hospital in Seongnam, Korea, in a press statement issued by the Endocrine Society.

"However, we also concluded that weight loss as a result of weight cycling can ultimately reduce the risk of developing diabetes in people with obesity."

Findings Add to Body of Literature by Including Korean Patients

The prospective study, published online November 29 in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism, included 3678 participants (56% women) in the Korean Genome and Epidemiology Study who were followed over 16 years and had health-related outcomes reported every 2 years.

Assessments of body weight over the course of the study showed that, after adjusting for possible confounders, including cardiovascular risk factors, for every one-unit increase in average successive variability (ASV), a measure of frequent weight fluctuation, there was an overall increased risk of mortality (hazard ratio [HR], 1.46; P < .001).

However, those with a lower baseline body mass index (BMI < 25 kg/m2) were more likely to have incident diabetes associated with each point in weight fluctuation (HR, 1.36; P = .003), whereas among those with a higher BMI at baseline (≥ 25 kg/m2), each point of ASV was in fact associated with a protective effect in terms of diabetes (HR, 0.76; P = .014).

The findings are consistent with previous research supporting the so-called obesity paradox, in which a dose–response relationship is seen between lower BMI and higher mortality, the authors note.

No association was seen, however, between rates of weight cycling and cardiovascular events.

"High body weight variability showed a protective effect on incident diabetes mellitus in obese subjects in contrast to a negative effect in subjects whose BMI was less than 25 kg/m2," they note.

"Therefore, body weight fluctuation would be a useful assessment tool to predict future health-related outcomes such as diabetes...and mortality."

These latest findings add to the evidence on weight fluctuations with important insights that now include a Korean population.

"The current study added novel findings in a Korean population to previous reports dominated by Caucasian data," the authors explain.

Yo-Yo'ing Body Weight Also Bad for Healthy People

Whereas previous research has suggested factors including smoking history and preclinical disease are important confounders, the new study in fact showed the highest adjusted HR linking increased weight fluctuation with mortality among healthy individuals who never smoked (HR, 1.66; P = .001).

"The association between high body weight variability and increased mortality was observed not only in participants with high cardiovascular risk, but also in healthy participants," the authors say.

As many as 80% of people who lose weight are estimated to either gain it back, returning to their previous weight, or even progress to a heavier status, because of complex processes of hunger and satiety hormones, as described in a scientific statement published by the Endocrine Society in 2017, as reported by Medscape Medical News.

These new results suggest that the weight fluctuations induce an unhealthy body state, although the exact mechanisms are not understood, say Jang and colleagues.

"Although the pathophysiological mechanisms of clinical hazards of body weight fluctuation are not yet fully clear, alteration of energy expenditure and neuroendocrine signals might have a role," they suggest.

In terms of people who have type 2 diabetes, weight fluctuations appear to be associated with increased risks of cardiovascular events including stroke, myocardial infarction, and death, compared with those who have a stable weight, according to research reported earlier this year by Medscape Medical News.

"However, the effect of body weight fluctuation on incident diabetes mellitus was positive in obese individuals and negative in their lean counterparts," in this latest study, Jang and colleagues conclude.

The study received support from the Research Program funded by the Korea Centers for Disease Control and Prevention.

J Clin Endocrinol Metab. Published online November 29, 2018. Abstract

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