been postulated to have negative health conse-
quences (Brownell et al. 1987). These would
include an increased energy efficiency, thus an
increased risk of weight gain, increased deposi-
tion of fat in the upper body (i.e. visceral fat),
lipid and lipoprotein disorders, reproductive
disorders such as delayed menarche and sec-
ondary amenorrhoea, and bone mineral distur-
bances consequent to secondary amenorrhoea.
Fortunately, most of these concerns have now
been clearly established to be unrelated to weight
cycling (van der Kooyet al.1993; Anonymous
1994; Jeffery 1996).
Athletes attempting to maintain a body weight
which is lower than that which is normal and
healthy for them is also a cause for concern.
These athletes are often in a state of chronic
energy deficit (i.e. energy expenditure>energy
intake for many days, weeks or months). In
female athletes, Loucks and Heath (1994a, 1994b)
have demonstrated that once the energy deficit
exceeds a certain critical level, reproductive and
thyroid function are suppressed, which might
serve as a trigger for athletic amenorrhoea (sec-
ondary amenorrhoea in the athletic population).
Amenorrhoea in athletes is associated with low
concentrations of 17b-oestradiol and proges-
terone, which are, in turn, associated with low
bone mineral density in the spine (Snead et al.
1992). The combination of disordered eating
(including energy deficit), amenorrhoea and
bone mineral disorders has been termed the
‘female athlete triad,’ with the assumption that
disordered eating can lead to menstrual dysfunc-
tion, which, in turn, can lead to bone mineral
disorders (Wilmore 1991). The female athlete
triad has become a topic of great concern and is
the focus of a recent position statement by the
American College of Sports Medicine (Otiset al.
1997).
Physiological and performance
consequences of weight loss
With rapid and moderate rates of weight loss,
there will be reductions in total body water,
muscle and liver glycogen stores, as well as in
642 sport-specific nutrition
other components of the fat-free mass (Oppliger
et al.1996). For the most part, these athletes are
already very lean prior to weight loss, and so
very little of the weight lost will be derived from
the fat stores. In fact, Friedl et al.(1994) have
reported that there is likely a lower limit to the
loss of body fat with weight loss in lean individu-
als. In a group of 55 soldiers participating in an
8-week Ranger Training Course, those who
achieved a minimum relative body fat of 4–6% by
6 weeks demonstrated only small additional
total and subcutaneous fat losses in the final 2
weeks and lost increasingly larger proportions of
fat-free mass. Therefore, as the athlete reaches a
low total fat mass, there is a reduced likelihood of
further losses of body fat with weight loss. Con-
sequently, the percentage of the actual weight
loss from the fat-free mass during rapid and
moderate rates of weight loss is likely to be high.
Generally, decrements in performance are associ-
ated with losses in the body’s fat-free mass
(Wilmore 1992).
Several recent papers have reviewed the
research literature on the effects of rapid and
moderate rates of weight loss on physiological
function and performance (Fogelholm 1994;
Horswill 1994; Oppliger et al. 1996). The results
of these reviews are summarized in Table 49.3.
Since there is typically an interval of time
between weigh-in and actual competition for
most sports, ranging from a few minutes up to
20 h or more, it is extremely important to under-
stand how physiological function and perfor-
mance respond following a variable period of
rehydration and replenishment of nutrients.
Unfortunately, while a great deal is known about
the effects of acute dehydration on physiological
function and performance, far less is known
about the regain in function and performance
with rehydration and intake of nutrients.
From this table, it is very clear that rapid or
moderate rates of weight loss can have major
effects on both physiological function and per-
formance. What is less certain are the potential
changes that occur with rehydration and food
intake during the interval of time between
weigh-in and competition. It appears that some