whole book.4th print

appears to be true, in that greater caloric restriction yields greater fat loss. However this ignores
the potential effects of extreme caloric restriction on metabolic rate, muscle loss, etc. A recent
review of twenty-two studies found that extremely low calorie levels, below 1000 calories/day,
caused a much greater drop in metabolic rate than even 1200 calories/day (10). So, there
appears to be a threshold level of caloric intake where metabolic rate is more greatly affected.

There are two common methods of setting calories for a diet: at an absolute calorie level, or
with an absolute caloric reduction. That is, consider two individuals, one weighing 120 pounds, the
other weighing 240 pounds and assume both have a maintenance calorie intake of 15 cal/lb.

First let us examine what happens if both decide to diet at 1200 calories per day. Table 5
compares their caloric intake relative to their maintenance levels.

Table 5: Comparison of two individuals dieting at 1200 calories per day

Subject Body Maintenance Intake Intake Daily

weight (lbs) calories (cal/day)* (cal/day) (cal/lb) deficit (cal)

1 120 1800 1200 10 600

2 240 3600 1200 5 2400

* Estimated at 15 calories per pound of bodyweight

It would seem logical that the second person’s body would perceive a greater deficit
(relative to resting levels) and decrease metabolic rate more so than the first person. While
anecdotal evidence suggests this to be the case, direct research looking at changes in metabolic
rate at different caloric intakes relative to bodyweight is necessary.

In a second situation, assume both individuals decide to create a 1000 calorie deficit
through some combination of diet and exercise. Table 6 compares them as above.

Table 6: Comparison of two individuals dieting at 1000 calories below maintenance

Subject Body Maintenance Intake Intake Daily

weight (lbs) calories (cal/day)* (cal/day)‡ (cal/lb) deficit (cal)

1 120 1800 800 6.6 1000

2 240 3600 2600 10.8 1000

* Estimated at 15 calories per pound of bodyweight

‡ For all practical purposes, whether the deficit is created through calorie restriction alone, or a

combination of calorie restriction and exercise, the body will only perceive that 800 or 2600

calories/day is being consumed.

In this case, the first dieter ends up with an extremely low calorie level, while the second
does not. It would seem logical that the first dieter would see a much greater drop in metabolic
rate under these conditions than the second.

A better method