which are composed mostly of water, can be as
high as 2–3 l · h–1in men acclimatized to heat over
the short term, and up to 10–15 l · day–1(Wenger
1988). Sauna and sudation or water vapour-
barrier garments have been widely used to
promote sweating, and the subsequent loss of
water can be considerable. These techniques are
not without risk or negative consequences (Vuori
& Wilmore 1994), but dehydration remains a
powerful tool for major losses of weight in short
periods of time.
Dehydration can potentially be induced by the
use of a high-protein diet, as water loss has been
associated with a high-protein diet. However, the
contribution of a high-protein diet to water loss is
most likely associated with the fact that carbohy-
drate intake is reduced. This forces the body to
rely more on fats, with the resulting production
of ketone bodies. It has been clearly established
that an excessive formation of ketone bodies, or
ketosis, leads to diuresis. Also, as the intake of
carbohydrate is limited, muscle and liver glyco-
gen stores are gradually depleted, resulting in
further water loss, i.e. the obligatory water loss
associated with glycogen degradation. Prescrip-
tion diuretics are also used to induce dehydra-
tion, although these are on the banned list of
substances for use by athletes (Wadler & Hain-
line 1989). Certain foods, particularly alcohol
and those foods containing caffeine, have sub-
stantial diuretic properties. However, caffeine is
a banned substance when ingested in excessive
quantities, e.g. 6–8 cups of coffee in one sitting
(Wadler & Hainline 1989). Refer to Chapter 28 for
further details.
Bloodletting has been stated as a method used
for weight loss by wrestlers (Horswill 1994);
however, it is unclear if this is widely practised.
This was not mentioned as a technique for
weight loss in the comprehensive review of
Fogelholm (1994), and was not included as a
technique for weight loss in a large survey of
high school wrestlers (Weissingeret al. 1991).
Most likely, bloodletting is not widely used for
weight loss in athletes, as most athletes do not
like invasive techniques and recognize the
640 sport-specific nutrition
obvious physiological and performance disad-
vantages of blood loss.
Purging behaviours are discussed in detail in
Chapter 39, and will not be addressed in detail in
this chapter. Self-induced vomiting and the use
of laxatives are the primary purging behaviours.
These behaviours can lead to transient weight
losses, but have substantial clinical risk, are
potentially addictive, and can negatively impact
athletic performance. While haircuts and inver-
sion might be used in hopes of reducing the
athlete’s weight, there is no evidence to support
the efficacy of these techniques.Health consequences of weight loss
Athletes generally lose weight for one of three
purposes: to qualify for a specific weight cate-
gory, to achieve a more aesthetic appearance,
and to improve performance potential. There are
a number of questions raised concerning the
potential for detrimental health consequences of
weight loss. While most critical attention has
been focused on rapid and moderate rates of
weight loss, there is also concern over gradual,
long-term weight loss. Each of these will be
addressed.
The primary concern with rapid and moderate
rates of weight loss is the consequences of severe
dehydration. Wrestlers have reduced body
weight by 4–5% in 12–24 h, and losses of up to
12% of body weight have been reported
(Brownellet al.1987; Fogelholm 1994). The great-
est percentage of the weight lost is from the total
body water stores. Water accounts for approxi-
mately 60% of the total weight of an adult man.
Thus, for a 70-kg man, total body water would
represent about 42 kg, or 42 l, assuming a water
density of 1.000. The intracellular fluid accounts
for about 67% of the total body water, or 28 l, and
the extracellular fluid accounts for the remaining
14 l. Of the 14 l of extracellular fluid, plasma
volume would account for 3 l and the interstitial
fluid would account for the remaining 11 l
(Guyton & Hall 1996). With rapid weight loss,
water is lost from each of the fluid compart-