More on Diet and Exercise
Dr. Matthew Surburg, a real M.D., weighed in — groan — on the issue of diet and exercise and provides very useful information. He posted this as a comment, but it truly deserves its own post. Thanks Doctor Surburg.
These reflections on the sedentary lifestyle and fast-food mindset in the United States are sound. I would caution people, however, against labeling low-carbohydrate diets as a “fad” alongside those that appear on the cover of supermarket checkout magazines.
Neither Atkins, nor other diets, nor medications, nor any other technique can change the underlying mathematics of human physiology and weight maintenance: energy in and energy out. If energy in, in the form of food consumed as expressed in the measure of Calories (properly, kilocalories) exceeds energy out, that is, expended by the body in the daily activity of maintaining cellular activity plus any other exertion that body may undertake, then that body will gain weight. If energy out exceeds energy in, that body will lose weight. Energy in is, obviously, affected by dietary choices. Energy out is, to a lesser degree, affected by exercise; vigorous exercise will increase total energy expenditure only modestly (say, 400 kilocalories in an hour on a stationary bike, compared to a basal metabolic rate of 1800 kilocalories per day). Of course, this does not make exercise less important, since exercise has other important cardiovascular benefits. However, it does point out that a person’s diet (that is, what and how much he eats) is a key consideration. In a starvation situation, the body will lower its basal metabolic rate, making weight loss more difficult, which explains why “crash” diets are counterproductive.
Low-carbohydrate diets (such as Atkins) have two basic mechanisms of action. The first (and, in my view, predominant) is that protein and fats stay in the stomach longer than refined sugars. This induces a sensation of satiety for a longer period, which makes a person eat less – affecting the energy intake portion of the equation in a desirable way. The second is by altering the body’s physiology to rely more on ketones and less on sugar for energy (all tissues in the body can run on either sugars or ketones, the exceptions being red blood cells, which run exclusively on sugar, and brain cells, which can run on either but are usually the last to make the switch to ketones when the situation requires it). This shift toward ketones, if taken to an extreme, can lead to ketoacidosis, the condition described in the article.
Since this complication has now been reported, it is now necessary to examine the concept of risk. I do encourage patients to think of a low-carbohydrate diet as a medical intervention, and to remember that every medical intervention – aspirin, amoxicillin, even bed rest – carries certain risks. The question is whether the benefit outweighs the risk. Although a serious complication did occur in this case, similarly serious complications can arise from just about every over-the-counter drug in the pharmacy – but they are all extremely rare. Statistically speaking, a low-carbohydrate diet carries less risk than driving to work.
As a physician, I am not a strong proponent of Atkins or any other low-carbohydrate diet, but I would describe my attitude as having gone from skepticism to cautious optimism. I usually will guide patients more toward high-protein diets (such as the “South Beach” diet) than toward the high-fat and –protein Atkins, simply because the high fat still intuitively seems unwise. However, the medical literature has not shown (yet) a broad risk to substantial numbers of people. Thus far, short-term data has been surprisingly positive, although long-term data is still lacking.
The key point people need to keep in mind is that approaching “weight loss” as a matter of being “on a diet,” even a low-carbohydrate one, will be unlikely to succeed unless it is part of an overall commitment to a healthy lifestyle, including eating healthy foods in moderation, getting regular exercise, and sufficient rest. In other words, the best results will flow from proper stewardship of the bodies God has given us.