Sunday, January 15, 2012

The Nutrition Debate #36: Modern Trends in Dieting

This column inaugurates a three part series on dieting, both prophylactic and therapeutic. We emphasize this distinction because we think it is generally unrecognized in the public health community (e.g. “Dietary Guidelines for Americans”). As a consequence most medical practitioners are unaware of it and, in my experience, diabetes educators simply refuse to accept it. The result: the general public does not see the importance of the distinction to their health and well being.

I just rolled by eyes in disbelief when I read that U.S. News and World Report earlier this month had a “panel of 22 experts” rate 25 diet plans and that Weight Watchers and Jenny Craig were among the top rated. These programs emphasize a “balanced diet,” eating less, and exercising more. The reason they continue to be popular, I think, is that the subscriber has to keep coming back year after year after regaining the weight they lost before. They are prophylactic in the sense that the goal is to prevent the consequences to health of being overweight, if they have not yet manifested themselves. (For a discussion of Metabolic Syndrome, see #9 at

The South Beach Diet
Another prophylactic program, The South Beach Diet (a trademarked term), is the creation of cardiologist Arthur Agatston and dietician Marie Almon. It is an ‘alternative’ to low fat approaches such as the Ornish Diet and the Pritikin Diet, advocated by the American Heart Association in the 1980’s. Agatston accepts the prevailing wisdom among cardios that low-fat diets reduce cholesterol and prevent heart disease; however, lower fat means higher carbohydrates, as there are only carbs, fat and protein as calorie sources. Sugar, a simple carb, and other simple carbohydrates, which are rapidly reduced to sugar (glucose) by the digestion process, lead to cycles of hunger. As a result, patients were consuming excess calories and gaining weight. Ironically, the attempt to reduce the risk of heart disease actually increased it, according to Wikipedia.

The South Beach Diet is relatively simple in principle: Replace “bad carbs” and “bad fat” with “good carbs” and “good fat.” The glycemic index (see column #7 in this series) is the scale on which bad carbs and good carbs are measured. And, being designed by a cardiologist, it should be no surprise that the South Beach Diet discourages all saturated fats and favors unsaturated fats, both monounsaturated and polyunsaturated. In sum, the South Beach Diet emphasizes eating the “right carbs,” the “right fats,” and lean protein. Eating this way helps to keep your blood sugar steady. And at the same time you avoid the highly processed, refined carbs that cause drastic swings in blood sugar. Once you stabilize your blood sugar, cravings are virtually eliminated. As a prophylactic plan, the South Beach Diet has some worthy aspects.

The Mediterranean Diet
Another popular prophylactic program is the Mediterranean Diet. Its origins date to the deservedly much maligned Seven Countries Study by Ancel Keys, based on his work in the 40’s and 50’s in which he carefully selected data from 7 countries out of a 22 country study to bolster his hypothesis. It lead to the diet-heart or Lipid Hypothesis (see columns #1 & #3), which in turn lead to the American Heart Association’s endorsement of the hypothesis. This let ultimately to U. S. government policy, through the 1977 McGovern Committee’s work, and the cataclysmic low-fat vs. low carb dichotomy we have in dietary theory today.

Nevertheless, in the 1990’s Dr. Walter Willett of Harvard University’s School of Public Health again helped popularize this diet program. Its main tenets are: high amounts of olive oil, the principal source of fat on the diet; low to moderate amounts of dairy products (principally cheese and yoghurt), fish, poultry and red wine; and low amounts of eggs and red meat. Interestingly, it is a diet high in salt (olives, salt-cured cheese, anchovies, capers, salted-fish roe, and salads dressed in olive oil). It emphasizes abundant plant foods, including legumes, and fresh fruit daily, typically for dessert. The total amount of fat calories in the diet is, however, about 30%, with less than a third from saturated fats. This is not dissimilar to the current Dietary Guidelines for Americans recommended percentages. One of the main differences is the high level of monounsaturated fats, most notable oleic acid, for olive oil. My personal favorite aspect of this diet is the glass or two or red wine daily, although a bowl of berries in full cream for desert once or twice a week would be a close second.

© Dan Brown 1/15/12

No comments:

Post a Comment