I am not fat, just big-boned

In some cases this may be true. People do have different frame sizes and different shapes which are not dependent on the total amount of body fat.

Sometimes, however, those who are fat use these possible differences as an explanation for what is really overfatness. How can we make the distinction? Skinfold thicknesses are a convenient and practical way to assess body fatness. Look in the mirror and see where there are bulges of skin with associated fat. Around the abdomen 'the pinch test' can be used; a fold of skin should not exceed 25 millimetres (one inch). The distribution of body fat is also important - fat around the abdomen is a greater risk to health than around the hips. Changes in fat in these two locations can be followed by checking circumferences with a tape measure.

The relationship between weight and height is also a guide to overfatness. As height increases, so muscle and bone mass should increase, but fat less so. Thus, if the weight increase is disproportionate to height, it usually indicates overfatness. The way to calculate and assess this relationship is to divide weight (kilograms) by height squared (metres), which is to say height multiplied by itself. This expression is known as BMI (body mass index).

BMI    =   weight (kg)
           height (m)X height (m)

The healthy range for BMI is 20 to 25. This is suitable for moderately physically active people. A person who engages in muscle building may increase their BMI with muscle rather than fat. But once BMI exceeds 30, there is definite overfatness. Likewise, a person who is inactive and undergoes muscle wasting may have a low BMI and still too much fat. (See BEING YERY FAT IS UNHEALTHY).

It is a fact that many obese (overfat) people tend to have relatively more muscle and greater bone density than people of normal weight. So it is possible for people to be both overfat and big boned. Frame size can be assessed by measuring the distance across the wrist or the elbow where there is usually little fat and no muscle to add to the measurements. People whose elbow breadth is smaller than that shown in the table on Elbow Breadth are considered to be small framed and those whose elbow is larger, are considered to have a large frame.

Appendix 1 is a table of weight in relation to height which takes into account variations in frame size.


Side view showing a right angle


Front view

Elbow breadth is measured by first raising the right arm to the horizontal position and flexing the elbow to form a right angle. Locate the bony protuberances on either side of the elbow and measure the distance between them. It is best done with someone else making the measurement, ideally by using a pair of calipers.

Height* Elbow breadth Height* Elbow breadth
158-161 cm

162-171 cm

172-181 cm

182-191 cm

192-193 cm

6.4-7.2 cm

6.7-7.4 cm

6.9-7.6 cm

7.1-7.8 cm

7.4-8.1 cm

148-151 cm

152-161 cm

162-171 cm

172-181 cm

182-183 cm

5.6-6.4 cm

5.8-6.5 cm

5.9-6.6 cm

6.1-6.8 cm

6.2-6.9 cm

* Height measurement assumes that a person is wearing shoes with heels of 2.5 cm.