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. 162