Too Fat to Start? Too Thin to Win?

A quick and easy way to check whether you are an ideal weight for your height is to work out your Body Mass Index (BMI). This is simply your weight divided by your height squared (kg/m2).

Values for BMI range between 15 (or less) to over 40 (see below). The normal range is 18.5 – 25.0. A BMI of less than 18.5 indicates that someone is underweight and over 25 indicates that they are overweight. If the value is 15 or less, it suggests an eating disorder or starvation and a value of over 30 indicates obesity. There are numerous online calculators that will work out your BMI for you – all you do is type in your height and weight and the instant calculator does the rest. One such instant calculator can be found on the BBC health pages at but there are many others.

BMI Categories:

  • Starvation: less than 15.0
  • Anorexic: less than 17
  • Underweight: less than 18.5
  • Ideal: from 18.5 to 24.9
  • Overweight: from 25 to 30
  • Obese: from 30 to 40
  • Morbidly Obese: greater than 40

This system is a good general indicator for average adults, but isn’t suitable for children, pregnant women, people over 60 or active individuals with developed muscles, since the calculation does not take frame or build into account. Muscles are heavier than fat, so, for example, an active person who exercises regularly may have a higher than average muscle mass, and may well fall into the overweight category when in fact they have a healthy body shape, very little fat and do not need to lose any weight at all. Further assessments, such as calculation of body fat percentage, are more useful in this instance.

Do you know what your BMI is?

If it is over 25 are you taking steps to bring it within the ‘ideal’ range? An increased BMI can lead to a significant increase in the chance of you developing diabetes, arthritis, heart disease, hypertension or stroke.

Conversely, the current trend for ‘size zero’, super skinny models is leading to increasing numbers of young people, especially girls, having a BMI of 18 or less. Just as a BMI of more than 25 can lead to health issues, an unhealthily low BMI can result in heart disease, osteoporosis and other premature, age-related illnesses. As discussed in the Scotsman earlier this year, Madrid fashion week has banned all models with a BMI of less than 18 in an attempt to reduce this trend, and others (including the Edinburgh fashion show) have followed suit.

Far more of us, however, battle to keep our BMI below 25: Statistics reveal that, in 2003, 43% of Scottish men and 34% of Scottish women had a BMI that fell between 25 – 30, while 23% of men and 26% of women had a BMI of greater than 30. In other words, 66% of men and 60% of women in this country are potentially overweight.

This information, coupled with the increased chance of ill health caused by being overweight, and the ever increasing cost of health care, is leading some insurance companies to include height and weight details on life assurance applications and to set higher premiums for people with a BMI of more than 30, the same as they do for smokers.

Need some help? If you would like to have your BMI calculated for you, want to know what your body fat percentage is or have a high BMI and need help reducing it, please contact Dr Amanda Gillies or look at

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