Measuring obesity in a way that is accurate.

Obesity has steadily been rising since 1993, and there are now approximately two thirds of all adults in England classed as being overweight or obese. This can lead to many health problems including heart problems, breathing issues, cancer and diabetes.

I’m sure we have all measured our BMI at some point using a calculator like this, but is it the best way? It works on the theory that if two people are the same height, but different weights, then the difference must be due to body fat. What it fails to take into account however is lifestyle, fitness, and muscle. Muscle is more dense than fat, so many athletes such as rugby players rank as morbidly obese, despite being in peak condition.

So what are the other ways of measuring?

Here are some methods from Harvard School of Public Health

Waist circumference

The extra fat carried on the waist is important regardless of things like BMI, so a waist measurement can be a good indicator.

Problems — The exact place of the waist isn’t standardised.

It can be hard to measure and less accurate with larger waists.

The string test

Measure around your belly button with a piece of string. Do not rely on your trouser size. Ideally your waist should be less than half your height. So if you are 6ft (72in) tall, your waist should be less than 36in.

Problems – its a rough test.

Quick and easy to give you a basis to work from.

Waist to hip ratio

Calculated by dividing the waist measurement by the hip measurement.

Problems — Standardised measuring locations again.

Two measurements more prone to error.

A ratio can give misleading information.

Skinfold thickness

Calipers “pinch” sections of skin, and the numbers can be used to predict body fat percentage.

Problems — Not very accurate.

Very hard to measure in large people.

Bioelectric impedance

We’re getting sciency now. Electric current is passed through the body. It has more resistance going through fat than water or lean mass. The numbers are then used to calculate body fat percentage.

Problems — Hard to calibrate.

Factors such as illness and dehydration can cause the body water to fat ratio to change.

Not as accurate as many other methods.

Underwater weighing

This is my personal favourite. They weigh you both in the air, and submerged in water. As fat is less dense than water, someone with high body fat with have a lower body density.

Problems — Time consuming.

Needs to be done in a research setting.

Not great for children, older adults, and very large people.

Combine some of the measurments

With all things, obesity measures need to be taken with some common sense. You know if you are in the gym all day, then your BMI is likely not a true representation of your size. Maybe combine some of the methods, factor in your lifestyle, and you should be able to tell if you are a healthy size or if you should consider making some changes.

Fat around the waist is metabolically active and seems to be more strongly associated with the risk of heart disease, stroke and diabetes.

The build-up of this fat is normally the result of a number of different factors, which include eating too much sugary, starchy food, drinking too much alcohol (particularly beer), not doing enough exercise, feeling stressed, sleeping badly, and of course, genetics. Once we are aware, we can start making those changes.


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