calories may occur (7). Most individuals will not be able to sustain exercise intensities high
enough to generate a large EPOC with aerobic exercise. With few exceptions, primarily elite
endurance athletes, the EPOC from aerobic exercise is unlikely to be significant in the overall
energy balance equation (1).
Following resistance training (and perhaps interval training), the magnitude of EPOC is
much higher. Increases in metabolic rate of 4-7% over 24 hours have been seen following
extensive resistance training (10). For an individual with a 2000 calorie per day metabolic rate,
this could amount to 80-140 calories burned following every resistance training session, the
equivalent of walking an extra mile.
Part of this increase reflects increased protein synthesis which rises for 24-36 hours and
which is energetically costly. The energy used for protein synthesis will come primarily from fat
stores (11).
Section 2: The effect of exercise on fat loss
Dieting without exercise
The most common approach to fat loss for most people is to simply restrict calories
without exercise. The biggest problem with weight loss by caloric restriction alone is an
inevitable loss in lean body mass (LBM), with a large part of the LBM drop from muscle stores,
and a drop in metabolic rate. The more that calories are restricted, the more the body lowers
metabolic rate to compensate. This reflects the body going into starvation mode to prevent
further weight loss. Depending on the amount of caloric restriction, the addition of exercise may
or may not have benefits in alleviating or preventing this drop in metabolic rate.
When food intake invariably increases again, the lowered metabolic rate makes the change
of fat regain very likely. As many individuals have found out, dieting by itself is not effective for
long term weight loss. In fact a recent analysis of studies shows that weight maintenance is
much better when individuals include exercise as part of their weight loss efforts than when it is
not. Other issues dealing with weight regain are discussed in more detail in chapter 14.
Exercise at different caloric levels
Although the exact reasons are unknown, the impact of exercise with caloric restriction on
fat loss is not as simple as eating less and exercising more. Many individuals have found that
eating too little and exercising too much can put the body into a starvation mode, and fat loss
slows or stops completely. The reason for this starvation response is not known at this time. It
is sufficient to say that moderate approaches to both exercise and caloric restriction tend to yield
the best long term results. Additionally, exercise appears to have its greatest effect with
moderate, not excessive, caloric deficits (12).
The key is to find the optimal combination of dietary modification and exercise to generate
maximum fat loss without any muscle loss. Of course, the right type of exercise is also