BMI, waist circumference severity increase risk for poor cardiometabolic health
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Adults with higher average BMI or waist circumference over 20 years have increased risk for poor cardiometabolic health in normal weight and overweight/obese groups, according to study findings.
Additionally, researchers found adults both with normal weight and overweight/obesity with a persistent history of central obesity have the highest risk for poor cardiometabolic health.
“Our findings support and further highlight the need for the maintenance of an optimum and stable BMI and waist circumference across the lifespan, even for adults who do not become overweight or obese,” Ellie Robson, BSc, a PhD student at Loughborough University School of Sport, Exercise and Health Sciences in the United Kingdom, told Healio. “Findings also further challenge the concept of ‘metabolically healthy obesity,’ by showing that this condition represents, at least partially, a lower level of exposure to BMI and waist circumference across twenty years of adulthood.”
Researchers collected data from Whitehall II, a study exploring the relationship between socioeconomic status, stress and cardiovascular disease. Of the Whitehall II study cohort, 3,018 adults aged 35 to 55 years working in government in London who participated in an exam from 1985 to 1988 were included in the analysis. Clinical and questionnaire data were collected five times over approximately 20 years of follow-up. Weight, height and waist circumference were measured at each visit. Overweight or obesity was defined as a BMI of 25 kg/m2 or greater, and central obesity was defined as a waist circumference of 102 cm or more. Blood pressure was also taken at each visit, and HDL cholesterol, triglycerides, glucose and insulin levels were obtained through fasting blood samples.
At outcome, 20 years after baseline examination, participants were considered metabolically healthy if they had zero or one of the following cardiometabolic risk factors: BP of at least 130/85 mm Hg or the use of hypertension medication, HDL cholesterol of less than 1.03 mmol/L for men or 1.29 mmol/L for women, triglycerides of 1.7 mmol/L or higher, fasting plasma glucose of 5.6 mmol/L or higher or use of a diabetes medication, and a homeostasis model assessment for insulin resistance of greater than 5.1.
The findings were published in Nutrition, Metabolism and Cardiovascular Diseases.
BMI, waist circumference severity increase cardiometabolic risk
About 61% of study participants had overweight or obesity at the final follow-up, and 37% were considered metabolically unhealthy with two or more cardiometabolic risk factors. Of those with metabolically unhealthy overweight or obesity, 69% had overweight or obesity at all time points in the study compared with 56% in the metabolically healthy overweight/obesity group. Of the 39% of adults with normal weight, 14% were metabolically unhealthy. About 61% of the metabolically unhealthy normal weight group never had overweight or obesity compared with 74% in the metabolically healthy normal weight group.
Each 1 kg/m2 increase in BMI was associated with a higher risk for being metabolic unhealthy for adults with normal weight (RR = 1.23; 95% CI, 1.1-1.38; P < .001) and adults with overweight or obesity (RR = 1.15; 95% CI, 1.11-1.18; P < .001). Similarly, each 1 cm increase in waist circumference was associated with a higher risk for being metabolically unhealthy for adults with normal weight (RR = 1.09; 95% CI, 1.05-1.12; P < .001) and adults with overweight or obesity (RR = 1.06; 95% CI, 1.05-1.08; P < .001). BMI variability was associated with an increased risk for being metabolically unhealthy for participants with normal weight (RR = 1.59; 95% CI, 1.1-2.31; P = .013) and those with overweight or obesity (RR = 1.35; 95% CI, 1.2-1.53; P < .001). Waist circumference variability was associated with a higher risk for being metabolically unhealthy only for adults with overweight or obesity (RR = 1.07; 95% CI, 1.02-1.11; P = .002). In models that were mutually adjusted for BMI or waist circumference severity and variability, the estimates for variability attenuated and became null.
Higher risks with overweight or obesity duration
Adults with overweight or obesity at all five examinations had a 1.6 times higher risk for metabolically unhealthy overweight or obesity at outcome compared with those who had overweight or obesity at only one examination. However, no association was observed in those with overweight or obesity at three or four of the examinations, and those with overweight or obesity at two of the time points had a lower risk for metabolically unhealthy overweight or obesity compared with those with overweight or obesity at one examination. However, duration of central obesity had stronger associations with being metabolically unhealthy in both normal weight groups and overweight/obese groups. For example, those with central obesity at all five examinations had a 4.2 times increased risk for having metabolically unhealthy overweight or obesity at outcome compared to having metabolically healthy overweight or obesity. Further, adults with central obesity at two or more time points had a higher risk for having metabolically unhealthy normal weight compared with those who never had central obesity (RR = 3.06; 95% CI, 1.23-7.6; P = .016).
“Research needs to be replicated in longitudinal cohort studies with a longer duration than 20 years to fully capture exposure to ‘lifespan’ adiposity,” Robson said. “Our study only looks at BMI and waist circumference exposure across 20 years, but ideally BMI and waist circumference would be measured across the whole life, or at least a longer period than our study.”
For more information:
Ellie Robson, BSc, can be reached at e.m.robson2@lboro.ac.uk.
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