They measured height, weight and body mass index - calculated by dividing weight in kilograms by the square of your height in metres.

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The studies measured the participants' body mass index (BMI), a ratio of their height and weight, but it wasn't able to take into account their body fat composition, or how much of their overall body weight was made up of fat versus muscle.

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Body Mass Index (BMI) is defined as the ratio of weight (in kg) to height (in meters) squared and is an inexact measure of body fat, though it supposedly establishes cutoff points of normal weight, overweight, and obesity.

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All models were required to have a body mass index -- a ratio of height and weight -- above 18, the minimum limit considered healthy by the World Health Organization.

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The study also took into account body mass index (BMI) - a measure which relates weight to height.

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Body Mass Index is calculated by dividing your weight in kilograms by the square of your height in metres.

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GPs will be advised to use the body mass index, where the person's weight in kilograms is divided by his height squared in metres, to get a reading.

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