Crude And True Calorie Deficits

Suppose you weigh 14 stones; your present balance point is 2,400 calories and your basal metabolism amounts to 1,600 calories daily. You select a 1,400-calorie diet so the crude deficit is 1,000 calories a day. The true calorie deficit turns out to be 900 at the start, because of the change in specific dynamic action; this becomes less when you actually lose some weight. When 20 pounds of the original 196 have been lost, the energy expenditure has dropped by about 110 calories for basal metabolism and 80 for activity, just because of the reduction in the body mass. At this stage the real deficit provided by the 1,400-calorie diet is only 900 - 110 - 80 = 710 calories daily. By the time another 20 pounds are lost the daily deficit, still on the same 1,400-calorie diet, is only 520 calories.

In the Minnesota Starvation Experiment during the war, our 32 young men volunteers came into calorie balance at 1,570 calories, whereas six months earlier, when they started the starvation diet, they needed 3,490 calories a day to hold weight constant. This is an extreme case of adaptation by men who were not fat to begin with but who lost a fourth of their original body weight. Besides the economy resulting from lowered basal metabolism and only three-fourths as much body weight to move around, they saved much energy by avoiding all surplus movement, in spite of being on a supervised regimen of ostensibly constant activity. The reduction of calorie expenditure by the fat person on a reducing diet is less than in these volunteers, fortunately, but the reducer must be careful not to reduce his activity. The temptation must be resisted to say you are weakened by the diet and therefore must have more rest than usual.

All this sounds discouraging, but actually it is fortunate that these are the facts of life. Without this automatic adjustment the world would be full of circus freaks, cadaverously thin and mon;trously fat. This phenomenon explains why, in times of famine or war and its prison camps, everyone does not starve to death in a hurry. It complicates reducing, but in spite of it you can lose weight successfully.

But how, it may be asked, does it happen that obviously incorrect schemes of predicting weight loss sometimes give the right answer? The answer is, first, that the predictions do not often really come very close except when the diet is adjusted as the programme is continued. Ordinarily, the patient is given a diet and a chart with the weight predicted week by week. If the weight does not follow the chart the patient is accused of cheating. It is not surprising that everyone who runs an obesity clinic on this basis says that most would-be reducers are liars.

The more attentive and kindly diet supervisor watches what is happening on the chart and revises the "activity factor" so as to come up with a "corrected" computation for the diet prescription. And the sensible patient watches the weight chart and "interprets", that is to say changes, the diet prescription accordingly. Either the diet or the chart is really being adjusted to the weight response so it automatically manages to get somewhere close to the predictions.

In this way everyone is happy, the weight gets lost, and the diet supervisor is convinced that this is a good demonstration of how well "theory" works out in practice. We do not object much except about the latter conclusion and all the mumbo jumbo attached. We prefer to be honestly empirical after learning the hard way by 20 years of dietary experiments in which patients were locked up, every item of food was carefully measured, and the activity was precisely controlled. We know that people differ, not only in basal metabolic rate but even more so in the movements they make and energy they expend.

Practical Reducing Programmes

Presumably a doctor has been consulted and has advised that a reducing progamme is desirable and that the proposed weight loss is safe. Any person who plans to lose more than a few pounds should always see a doctor before going on a diet. It is seldom that obese people should not reduce but contra-indications must be ruled out.

Before starting on any reducing diet an estimate of the present calorie balance point is desirable. Unless something is known about how many calories of food maintain the present weight without change, it is impossible to make a reasonable selection of a reducing diet. For most people this "balance" point is really just about what they are now eating, so a good estimate can be made from measurement of the present diet or of any good diet that holds weight steady over a period of several weeks.