Waist Size, Not Just BMI, Predicts Mortality Risk in Postmenopausal Women, New Study Finds
A simple waist circumference measurement may be a more accurate predictor of mortality risk for women after menopause than the commonly used Body Mass Index (BMI), according to a new US study. The findings underscore the importance of assessing belly fat as a key health indicator, even in individuals with a seemingly healthy BMI.
The research, highlighted in the German Ärzteblatt and conducted by Aaron Aragaki of the Fred Hutchinson Cancer Center in Seattle, analyzed data from a large cohort of women. The study challenges conventional wisdom surrounding weight assessment and offers a more nuanced approach to understanding health risks in postmenopausal individuals.
The Limitations of BMI
For decades, the BMI has been the standard metric for evaluating body weight. However, this study suggests its limitations, particularly in women after menopause. Researchers evaluated data from 139,213 women aged 50 to 79 who participated in the ongoing “Women’s Health Initiative,” a large observational study in the United States. Participants were categorized based on traditional BMI ranges: normal weight (18.5 to 25), overweight (25 to 30), obesity class 1 (30 to 35), obesity class 2 (35 to 40), and obesity class 3 (over 40).
However, the study also incorporated waist size as a critical measurement, dividing participants into groups based on circumferences of 80, 90, 105, 115, and over 115 centimeters. This allowed researchers to assess the impact of abdominal fat, which is strongly linked to cardiovascular and metabolic diseases.
Waist Size as a Key Indicator of Risk
The central finding of the study revealed a consistent trend: women after menopause with larger waist sizes exhibited a higher mortality rate across all BMI categories. This suggests that even women within a “normal” weight range, according to BMI, can be at increased risk if they carry excess abdominal fat.
Specifically, the data showed:
- Women with a normal BMI but a large waist circumference faced a mortality risk comparable to those with obesity class 1 and a normal waist circumference – a 12% increase compared to women with normal weight and waist size.
- Women with obesity class 1 and a large waist circumference experienced a 45% increase in mortality.
- Even women with massive obesity (BMI over 40) but a normal waist size had a 40% higher mortality rate compared to those with normal weight.
“The measurement of the waist circumference is a simple and inexpensive way to assess belly fat,” one analyst noted. “However, it is rarely used in the context of patient care.”
Implications for Healthcare and Prevention
The study’s findings align with recommendations from the International Atherosclerose Society (IAS), which advocates for a more comprehensive approach to risk assessment than relying solely on BMI. The researchers emphasize that measuring waist size should be a standard component of health evaluations, particularly for postmenopausal women.
Furthermore, the study suggests that individuals identified as high-risk due to both high BMI and significant abdominal fat should be prioritized for intensive interventions focused on weight normalization and improved fat distribution. This proactive approach could significantly reduce mortality rates and improve overall health outcomes.
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The research underscores a critical shift in how we understand and address weight-related health risks, moving beyond a single number to a more holistic assessment of body composition.
