Dr. Grossi's Blog

The Failure of Low-Calorie Diets

Dr. Philip Grossi
Tuesday, 03 April 2012

If you have not read the previous blogs on starvation (Dieting & Starvation) and it's effects as well as the effects of re-feeding, I suggest that you go back and read those quickly as they provide context for this blog.

The community experience with low-calorie diets is extensive, having been suggested by many doctors and professionals for over forty years.  Their success rate as measured by keeping weight off for a few years is almost zero. Why is this the case?

First, some of the most popular diets recommend 800 to 1000 calories per day. Often people will be delighted when they look at the scale in the first two or three weeks. Unfortunately 70 per cent of the weight loss is water, not fat. Most people don't realize that when they loose water they are also loosing essential electrolytes and nutrients such as potassium, sodium, magnesium, phosphorus, and calcium. The body tries to compensate by retaining sodium which leads to water retention, which Keys labeled re-feeding edema. Also, increased insulin production needed for metabolism of food fosters retention of sodium and thus fluid.

Another change produced by extremely low-calorie diets or starvation (your body can't distinguish) is the reduction in the rate at which your body converts caloric intake into energy and slows to conserve the few available calories. This produces fatigue, dry skin, hair loss, cold intolerance, depressive symptoms and others as described by Ancel Keys and cited in a prior blogs. Indeed, your body becomes more efficient with each episode of starvation and this accounts for the increasing difficulty in loosing weight. Eating actually increases metabolic rate and so skipping meals works against the goal of weight loss. I have had a number of patients who have eaten six to eight small meals per day and have lost weight. Another aspect of eating frequently is that one is eating when one is not hungry and preoccupation with food disappears.illustration to low-calorie diets looping blog

Skipping meals or starving also produces binging once food is available as was demonstrated in the Minnesota study. Often this is experienced by the dieter as a lack of self-control or will. This produces reinforced efforts to eat less with subsequent failure. The person is fighting his/her own biology which is responding as if it is in a famine. Again, this was described 62 years age by Keys.

What is the secret to loosing weight then?  Calculate you daily caloric need at rest and eat about 12 to 15 per cent fewer calories distributed in frequent meals and exercise moderately, i.e., walk about 30 minutes three or four times each week. You can calculate your daily resting caloric need or use the rule of thumb which is about 10 calories per pound of weight.