(Allow me to step up on a soapbox for a moment: Please shout it from the rooftops that avocados, nuts, and olives are infinitely more healthy than white flour or high-fructose corn syrup!)

A few books bring into play the glycemic index, or GI, a measure of how quickly an individual food raises blood sugar. Some take it a step further and tell you how to calculate glycemic load, or how much a normal portion of food will raise blood sugar. All of these diets, thankfully, emphasize the need for green leafy vegetables in the diet. And most add, somewhat grudgingly, that whole-grain products are okay for long-term weight maintenance.

Other books bring up a good point about allergens. Even if you do not have what the conventional medical community considers a true food allergy, it is very possible to have a hidden food intolerance, especially to omnipresent food staples such as dairy, wheat and other gluten grains, soy, or corn. (If you suspect you may have a food intolerance, try an elimination diet and then slowly add back in the potential allergenic foods one at a time.)

By labeling carbohydrates as the bad guys, the focus shifts to favoring animal foods (meats, fish, eggs, and cheese) over plant foods. Stricter phases of certain plans do not even allow for most varieties of fruit or beans. Can you honestly say that a beefsteak is better for you than lentils or a fresh mango? By restricting the amount of plant foods, unfortunately, it also means you are restricting your sources of dietary fiber, vitamin C, antioxidants, and a whole host of phytonutrient chemicals which are protective factors against everything from cancer to heart disase.

While the body can indeed convert dietary fat or protein into glucose, it does so only at considerable expense to the kidneys and liver, which are forced to work overtime in order to convert amino acids into glucose. When too much protein is consumed, the kidneys need to deal with the excess nitrogen by increasing urea output, which means more urination, dehydration, and depletion of the body's calcium stores (i.e., bone loss which could lead to osteoporosis). Atkins' diet followers are constantly urged into "ketosis," which, while a natural adaptive mechanism for coping with inadequate glycogen stores, can cause frightful buildup of toxins, loss of body protein stores (i.e. muscle), and tremendous strain on the liver and kidneys.

The books regarding glycemic index and glycemic load do have a point about being careful about the types of carbohydrates you consume, but too often their claims about "good" and "bad" carbs are based solely on a food's glycemic effect. One, an individual food's glycemic index or GI can vary greatly depending how (and how long) it is cooked, prepared, processed, or even ripened. Two, by that logic alone, a person should eschew watermelon or carrots in favor of french fries or full fat ice cream. How often do you eat only one type of food at a meal? The fact is, you can easily make for a moderate glycemic load by balancing low and high GI foods within the same meal. Some books remember to mention that, but not all.

Any claim that Americans are protein-deprived must be taken with a grain of salt. It's true that some amounts of protein and fat at each meal can help balance blood sugar levels. But especially in Western cultures, it isn't lack of protein that we should be concerned about. Protein RDA's made by the U.S. Department of Agriculture are made with a built-in buffer, just as any other RDA. The World Health Organization emphasizes that a diet of around 5-8% of calories from protein, as long as total calories are sufficient, is more than adequate for the average person. (Athletes need perhaps 8-10% of daily calorie needs from protein, which is still met easily without the need for meat at every meal.) And more and more studies are showing the health hazards of a diet too high in protein, particularly from animal sources. As with all aspects of nutrition, the key is to strike a balance and moderation, not claim absolutes of "good" or "bad."

The most ironic thing of all is that even if so-called "low impact carb" meals don't raise blood sugar, they still cause the release of insulin into the bloodstream. Actually, overeating anything --- carbs, protein, or fat --- can unfavorably raise blood insulin levels. So don't think that skipping the spaghetti means that you can then indulge in as many meatballs as you'd like.

The fact that the diet books advocate "whole food sources" of nutrients doesn't seem keep their companies from manufacturing and marketing their own brands of meal-replacement bars, powders, and shakes. And carbohydrate-conscious consumers can have a field day in the supermarket with low- or controlled-carb versions of everything from bread to pasta to breakfast cereal to vegetarian entrees, and even milk or peanut butter. At first glance, this seems innocent enough; they miss their bread and pasta, so what's wrong with providing a suitable alternative? The problem is that these "foods" are just as refined and unnatural as the conventional foods they are supposed to be replacing; sometimes even more so.

My favorite example of this is the new "low carb peanut butter." Real peanut butter (where the ingredients are peanuts, oil, and possibly salt) is naturally "low carb," a great source of monounsaturated fats (the "good fats"), and as natural as you can get outside of raw peanuts. It's when your favorite brand name company adds all the sugar and hydrogenated oils that the health factor drops significantly. The low-carb peanut spreads not only contain the usual trans-fats, but now artificial sweeteners as well. Yummy.

And this is typical of what manufacturers do to make foods suitable to the carbo-phobe. They add cream, oil, soy or whey protein isolates, wheat gluten, oat fiber, aspartame, sucralose, hydrolyzed collagen (gelatin)...the ingredients list grows. How can it be argued that such an item is more healthy than you than, say, a banana and some almonds? Just because something is edible does not mean that it can be called food.

The definition of a "diet" is what one eats on a regular basis. But it has instead come to mean something one follows for the short-term, just long enough to lose x pounds, go back to their normal diet and habits, regain the weight (and then some), and try the next new fad that comes along. John Robbins laments that he strongly objected to his publisher giving his first book the title Diet For a New America, because he hates the word "diet" and its connotations, and is disgusted with the weight-loss industry. Interestingly enough, his first book wasn't even intended to be a weight-loss program. He discussed the personal and ecological benefits of a "compassionate" plant-based diet. But ironically, many people who read his book followed his suggestions about healthy lifestyle changes, and found out that they lose excess weight and were much healthier overall.

Change your lifestyle, get healthy. What a concept!

Added 3/28/04, revised 3/15/05