Amazon.com (ISBN 0060392428, Hardcover)

Here's the follow-up to The Zone and Mastering the Zone. Author Barry Sears, Ph.D., has formulated a way for readers to follow his diet plan (30 percent fat, 40 percent each carbohydrates and protein) by breaking down foods into measurable units, à la Weight Watchers. It's designed to make eating on the run--even if you're stopping at McDonald's--a Zone-friendly experience. But it's not exactly a piece of cake.

Anyone who hated word problems in math class may be slightly baffled by the necessary calculations for foods not listed in the charts. For example, if you want to convert a serving of cereal into Zone blocks, you need to look at the label and subtract the grams of fiber from the total grams of carbohydrate; this gives the total of insulin-promoting carbohydrate. Divide this result by 10. (Although to be accurate, it should be divided by 9, as Sears has assigned 9 grams to each carbohydrate block; he says you may as well round up to 10, since that makes the math easier.) And there you get your Zone block. As long as your total blocks stay within the 40-30-30 ratio, you're in the Zone.

Even more confusing are the measurements for some of the "pre-calculated" foods in the charts. For example, 80 fluid ounces of Rice Dream Rice milk equals 39 carbohydrate blocks and 8 fat blocks. While it's unlikely anyone would guzzle down 10 servings at once, it is likely they'd have a hard time finding this product in the listings in the first place, as it's listed under "milk, nondairy," not "rice milk." Many of the other listings are equally frustrating. To get one carbohydrate block of Schweppes ginger ale, you need to drink 3.3 fluid ounces. If you're working with a 12-ounce can, you can do some rounding, but if you have a liter-sized bottle at home, you're going to need a good eye to get that third of an ounce in a measuring cup. It's also hard to believe someone would eat eight-tenths of a slice of Pepperidge Farm bread to get one carbohydrate block, or six-tenths of a teaspoon of Bernstein's Caesar salad dressing to get one fat block. Dieting shouldn't be this difficult.