maximum fat loss without any muscle loss. Of course, the right type of exercise is also
important. In an attempt to develop guidelines for calorie intake and exercise we will examine the
impact of exercise on three different dietary conditions: maintenance calories, low-calorie dieting
(10% below maintenance levels to 1200 calories per day), and very-low-calorie dieting (below 800
calories per day).
Exercise at Maintenance calories
The most basic approach to create a caloric deficit is through the addition of exercise to a
maintenance calorie diet. As stated previously, while the addition of aerobic exercise with no
change in diet causes fat loss in men, it does not reliably do so in women (3,14).
At maintenance calories, in both men and women, the performance of resistance training
causes a loss of bodyfat with no changes in dietary habits. (14-18) At this calorie level, weight
training alone generally causes a greater fat loss and muscle gain than endurance exercise alone
(14,15). In 8 weeks, beginning trainees can expect to gain 2-4 pounds of lean body mass and lose
2-4 lbs of fat with weight training alone as little as 30 minutes three times per week (17-19).
In a longer study of 20 weeks, women performed three sets of eight repetitions in four
lower body exercises (12 total sets) twice per week. At the end of the study, they had gained 10
lbs of muscle and lost 10 lbs of fat (20). The overall changes may have been even more
significant had the subjects trained their upper body as well. This occurred without dieting or
aerobic exercise, although fat loss would have probably been greater and/or faster with the
addition of either.
Considering the low caloric expenditure of weight training, it is difficult to understand how
weight training can cause fat loss at maintenance calories. The reason is the indirect effect of
weight training on metabolic rate. Every pound of muscle added through weight training burns an
additional 30-40 calories per day in both men (17,18) and women (18).
A beginning exerciser can gain 3-4 pounds of muscle in the first 8 weeks of training with
even the most basic of programs. This gain may increase metabolic rate by 120-150 calories per
day, the equivalent of walking 1.5 miles every day. At maintenance calories, the addition of
aerobic training to weight training will yield even better fat loss results. However, weight training
is critical for long term fat loss and weight maintenance.
Beginners can gain 3-4 lbs of muscle and to lose of 5-10 lbs of bodyfat over 8 weeks
following a very basic program of resistance training (1 set of 8-12 repetitions of 8-10 basic
exercises) and aerobic exercise (30’ at 65% of maximum heart rate), which is described in more
detail in chapter 27 (21).
Exercise with low-calorie dieting (10% below maintenance to 1200 calories/day)
With a moderate calorie restriction (from 10% below maintenance to approximately 1000
calories below maintenance) without exercise, there is inevitably a decline in resting energy
expenditure and a loss of muscle. When exercise is added fat loss increases and the loss of
muscle decreases. The drop in metabolic rate is also decreased. (22-25).