Trouble In The Zone

A recently popular example of a higher-fat/higher-protein diet is the Zone diet, which requires that a specific ratio of carbohydrates, fat and protein be eaten at each meal. By modifying its approach and providing for more carbohydrates than the standard high-fat/high-protein diets, the Zone diet prevents ketosis and its associated complications. In addition, the Zone diet recommends limiting saturated fats, another positive.

Nevertheless, other difficulties remain. High-protein diets in general cause excess accumulation of the ammonia products that are a natural result of protein metabolism. This leads to a diuretic effect, increasing the loss of calcium through the urine and promoting osteoporosis.

As noted before, protein directly stimulates insulin secretion by the pancreas, and synergistically increases the release of insulin caused by carbohydrates. The net result is that a substitution of protein for carbohydrate does not reliably lower insulin levels. To consistently lower insulin secretion, you need to emphasize lower-glycemic-index carbohydrates in the diet and eat fewer calories.

Finally, the Zone recommends a four-to-three ratio of carbohydrate calories to protein, based on a postulated effect on the body’s production of eicosanoid hormones. The eicosanoids are compounds that are widely produced throughout the body, and help to regulate such diverse functions as blood pressure, clot formation, the immune system and fat metabolism.

According to Zone theory, all disease—from heart ailments to cancer—can be ascribed to derangements in eicosanoid production. While these hormones are important to the body’s function, it is difficult to imagine that they exert this much effect on health.

Moreover, the actual effect of the Zone diet on eichosanoids has not been measured. And consistently maintaining the 4:3 ratio of carbohydrates to proteins at each meal is a difficult regimen to follow. In the end, the Zone diet appears artificial in its implementation and unrealistic in its expectations.

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