Many organisations have stated that waist size can be a better indicator of obesity than the body mass index (BMI).
This is because the location of body fat is a critical factor in the risk of developing health issues. As a result, people in the healthy BMI range could still have excessive body fat, unknowingly putting them in a high-risk group for obesity-related problems.
What is BMI?
BMI uses a person’s height and weight to work out an indicator of general health. The calculation divides an adult’s weight in kilograms by their height in metres squared, e.g. a BMI of 25 means 25kg/m2.
In the UK, BMI scores are then defined into categories:
- Lower than 18.5 is considered underweight.
- 5 to 24.9 is considered a healthy weight.
- 25 to 29.9 is considered overweight.
- 30 and above is considered obese.
However, muscle is much denser than fat. Therefore, highly muscular individuals such as heavyweight boxers, weight trainers and athletes could be classed as obese by their BMI even though they’re a healthy weight.
The calculation also fails to recognise the type or location of fat. But scientists increasingly appreciate these two factors play a significant part in determining whether a person is at risk of developing serious illnesses such as cardiovascular disease or cancer.
Why waist-to-hip ratio is a better indicator than BMI
It’s long been thought that waist-to-hip ratio is a better indicator of an adult’s health than BMI. The waist-to-hip ratio (WHR) is the ratio of the circumference of the waist to the hips.
For example, the waist measurement is divided by the hip measurement. Therefore, a person with 76 cm waist and 97 cm hips would have a waist-hip ratio of about 0.78.
The World Health Organisation states that a waist-hip ratio above 0.90 for males and above 0.85 for females is defined as abdominal obesity. The National Institute of Diabetes, Digestive and Kidney Diseases states that women with waist-hip ratios of more than 0.8, and men with more than 1.0, have an increased health risk because of their fat distribution.
Why extra fat around the waist is dangerous
A study by the University of Iowa examined data from nearly 157,000 postmenopausal women who were followed for up to 20 years. The University discovered that those with a BMI reading of less than 25 but a waist circumference of 35 inches or more had a 31% higher risk of dying during the study period than women of normal weight with a waist of less than 35 inches.
The reason for this is that unhealthy or visceral fat wraps itself around internal organs. This is why people with a healthy BMI could still have increased health and mortality risks because they’re storing fat around their middle.
Studies have linked excessive visceral fat with raised blood pressure, heart disease, type 2 diabetes, strokes, and certain types of cancer, including breast cancer and colon cancer.
Check at a glance with Waistchecker
Because central body fat is such a serious issue, Waistchecker is designed to highlight an increase in waist size. It’s a simple, colour-coded tape measure that helps keep track of weight loss – and shows progress at a glance.
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