no aerobic exercise should be done to avoid metabolic slowdown.
The decrease in metabolic rate seen with very low-calorie diets makes weight regain likely.
Eventually, a dieter will have to eat. And when normal eating habits are resumed after a period
of starvation dieting, weight and bodyfat regain will be the result.
Therefore the best fat loss solution, in terms of both fat loss as well as maintenance of
that fat loss, is to eat at maintenance (or a slight deficit, no more than 10-20% below
maintenance) in combination with resistance training (33). Aerobic training can be added as
required and will increase fat loss as long as it is not overdone. For most, 20-40’ of aerobic
exercise several times per week should be sufficient. In this case, more is NOT better. However,
if an individual has significant amounts of fat to lose, a greater frequency of aerobic exercise may
be beneficial.
The ultimate point of the above discussion is this: resistance training coupled with a slight
decrease in energy balance is the key to fat loss. The inclusion of aerobic training can increase
fat loss as long as total calories are not taken too low.
Section 3: The fat burning myth
A commonly held idea in the field of exercise is that one must burn fat during exercise in
order to lose bodyfat. This has led to the development of charts which indicate a certain ‘fat
burning zone’ during aerobic exercise. However, recent research as well as anecdotal experience
draws into question the idea of the fat burning zone, a topic discussed in greater detail below.
The fat burning myth
A very prevalent misconception about aerobic exercise is the so-called ‘fat burning zone’
which is supposed to optimize fat loss. It is true that a greater percentage of fat is used during
low-intensity exercise (see chapter 18 for details). This suggests that low-intensity exercise is the
best form of exercise to lose fat (6). However, due to the low total caloric expenditure, the total
amount of fat used is small. As exercise intensity increases (up to about 75% of maximum heart
rate), while the percentage of total calories derived from fat is smaller, the total amount of fat
used is greater (34).
The physiology of fuel utilization described above ultimately ignores the following fact: the
utilization of fat during exercise has little bearing on fat loss (1). Numerous studies have
compared the effect of different intensities of aerobic exercise on fat loss. As long as the caloric
expenditure is the same, total fat loss is identical whether the exercise is done at low or high-
intensity (35-37). That is, the fuel used during exercise is of secondary importance compared to
the amount of calories expended. As long as more calories are burned than eaten, the body will
reduce fat stores.
One thing to note is that as the intensity of exercise increases, the duration of activity
decreases (see chapter 24). This means that some individuals will burn more calories by using