Slimming World BMI calculator

BMI stands for Body Mass Index. It’s calculated by dividing your weight (in kilograms) by your height (in metres), squared.

If you’re over 18, BMI is a calculation used by health professionals to assess any possible weight-related health risks. For the majority of adults (excluding pregnant women), BMI gives a pretty good indication of how much body fat you’re carrying and what that means for your health. It’s also a simple and useful way to monitor your progress as you lose weight.

 

In some circumstances, though, BMI can’t give a true picture. This is because it doesn’t distinguish between weight you carry as body fat and weight you carry as muscle. So for example, very muscular athletes may be heavy in mass, but not have a lot of body fat – meaning they’d be misclassified as overweight or obese by the BMI method.

 

If your BMI is 35 or less, your waist-to-height ratio can be another useful way to indicate whether your health is at risk. To find your waist-to-height ratio, measure around your waist with a tape measure or a piece of string – your waist is the midpoint between the bottom of your ribs and top of your hips (not your trouser size as it can be surprisingly misleading). Divide your waist measurement (cm) by your height (cm) then take a look at this BMI table.

 

Waist-to-height ratio

Healthy range: 0.4 – 0.49
Increased risk: 0.5 – 0.59
Greater risk: 0.6 and above

The healthiest BMI range for most adult women is between 18.5 and 24.9.

 

The healthiest BMI range for most adult men is exactly the same – between 18.5 and 24.9.

 

If your BMI is below 18.5 you are underweight – and intentionally trying to lose weight or stay in this range may be unhealthy.

 

If it’s between 25 and 29.9 you may be at greater risk of developing weight-related health problems.

 

If it’s 30 or over, your health is at considerably greater risk.

 

It can be a shock to calculate your BMI and discover it’s in one of the latter ranges. At Slimming World, so many of us have been there – and we truly understand what you’re feeling. We’ll help you make really simple, sustainable changes so you can start to lower your risk of weight-related health problems without ever going hungry – naturally bringing your BMI down along the way.

The easiest way is to use our BMI calculator, or this BMI chart – both of which do the maths for you.

 

You’ll spot in the chart that in addition to the four BMI ranges (white: underweight, yellow: healthiest range, red: greater health risk and purple: considerably greater health risk), there are two dotted lines. This is because the point at which someone’s health is at risk due to their weight varies between ethnic groups.

 

So if you’re Asian (South Asian and Chinese), black African or African Caribbean, please use the area between the dotted lines as an indicator for when your health may be at greater risk due to your weight, and the area to the right of the dotted line as an indicator that their health is at greater risk.

At Slimming World we’ll never dictate what your BMI ‘should’ be – regardless of your age, height, gender, starting weight or anything else.

 

If you’re over the age of 18, a healthy BMI is between 18.5 and 24.9.

 

If you’re under 18
BMI of children and teens is calculated differently. If you’re under 18 and concerned about your weight, or you’re a parent supporting a child with healthier eating, there’s a specific adult’s and children’s BMI calculator on the NHS website. Our Family Affair resources also support parents and guardians in helping their children to make healthier lifestyle choices. Ask your Consultant for a free booklet in group or read more on the Slimming World blog.