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Table 2: Comparison of bodyfat levels

Group Essential fat (%) Average bodyfat (%) Recommended (%)

Men 3 11-18 10-15

Women 9-12 21-28 18-25

Male bodybuilder 3 3-4 N/A

Female bodybuilder 9-12 8-9 N/A

Measuring bodyfat (3)

Over the years, many methods have been used to measure bodyfat. The method currently
considered the ‘Gold Standard’ is underwater weighing. Based on the fact that fat floats better
than muscle (technically, fat is less dense than muscle), bodyfat percentage can be estimated by
weighing an individual on ground and again when submerged underwater.

Many assumptions and estimations are made during underwater weighing. Although the
subject is instructed to exhale all air from their lungs, there will always be a small amount left. A
correction for this residual air must be made. Additional estimations are made on the density of
bone, fat and muscle but these vary greatly depending on race, age, activity level, etc. Many of
the assumptions which are being made for underwater weighing have been found to be incorrect
(3).

The other methods of bodyfat measurement are generally based on underwater weighing.
Descriptions of the most common methods of measuring body composition appear below.

Girth measures

Girth methods of bodyfat estimation typically use weight and several girth measures (i.e.
circumference of the waist, wrist, or hips) to estimate bodyfat. While these measurements are
fast and easy to perform, they are notoriously inaccurate as they cannot distinguish between an
individual with excess fat, excess muscle, or simply a large bone structure.

For example, an equation which used hip circumference would vastly overestimate the
bodyfat percentage of an individual with genetically wide hips, even if that person were very lean.
Although girth measures can provide another measure of progress on a diet, they should not be
used to estimate bodyfat percentage.

Bioelectrical impedance (BIA)

BIA estimates bodyfat by running a small electrical current through the body based on the
fact that muscle, fat and water conduct electricity at different rates. With several other
variables (height, age, weight), the BIA machine will estimate body fat percentage. BIA can be
severely affected by hydration state. Due to changes in hydration during ketogenic diets
(especially cyclical ketogenic diets), BIA is not recommended.