The biggest problem with the tape measure is obtaining consistent tension as it is quite
easy to pull the tape tighter to get a smaller measurement. Ideally, the tape should be pulled just
tight enough that it slightly depresses the skin. Another option is to have someone else take the
measurements.
Also as discussed in chapter 8, keep in mind that changes in the tape measure are affected
by changes in muscle mass. Those starting an exercise program often gain muscle more quickly
than they lose bodyfat. This can show up as a temporary increase in tape measurements.
Section 2: Measuring ketosis
Whether correct or not, many ketogenic diets tend to live or die by the presence of ketones
in their urine. The presence of ketosis, which is indicative of lipolysis can be psychologically
reassuring to ketogenic dieters. However it should be noted that one can be in ketosis, defined as
ketones in the bloodstream, without showing urinary ketones. Since dieters will not be able to
determine blood ketones, other methods are necessary. The two measurement tools which most
individuals will have access to are Ketostix (tm) and glucometers, which are small machines used
by diabetics to measure blood glucose level. Both are discussed below.
Ketostix (tm)
Probably the most common tools used by ketogenic dieters are Ketostix (tm) or Diastix
(tm), which measure the urinary concentrations of either ketones or ketones and glucose
respectively. Typically, they are used by Type I diabetics for whom the presence of high urinary
ketones/glucose can indicate the start of a diabetic emergency. Since a non-diabetic individual
shouldn’t show glucose in the bloodstream, there is no reason for most ketogenic dieters to use the
Diastix (tm). Only Ketostix (tm) are discussed here.
Ketostix (tm) use the nitroprusside reaction, which reacts to the presence of acetoacetate,
to indicate the concentration of urinary ketones. Depending on the concentrations of
acetoacetate, the Ketostix (tm) react by turning various shades of purple with darker colors
indicating greater concentrations.
Since Ketostix (tm) only register relative concentrations, rather than absolute amounts,
changes in hydration state can affect the concentration of ketones which appear. A high water
intake tends to dilute urinary ketone concentrations giving lighter readings.
Ketostix (tm) are typically used to indicate that one’s diet is truly inducing a state of
ketosis. The problem is that Ketostix (tm) are a only an indirect way of measuring ketosis. Recall
from chapter 4 that ketosis is technically defined by the presence of ketones in the bloodstream
(ketonemia). Ketones in the urine simply indicate an overproduction of ketones such that excess
spill into the urine. So it is conceivable for someone to be in ketosis without showing urinary
ketones.