Eating to live longer: It can be a page turner

As for Braverman's claims about brain chemistry, scientists in the 1970s and 1980s began to demonstrate a link between diet and brain neurotransmitter levels. Since then, researchers have, in fact, shown that levels of brain chemicals, such as dopamine, can become depleted with age; they've also linked obesity with deficiencies in certain brain chemicals. Braverman cites such studies, but for proof that his regimen works he points to the successes of his patients, whose cases are reported throughout the book. With supposedly brain-chemical-boosting dietary changes and exercise plans, the profiled patients reportedly shed pounds, gained energy and improved their life outlook. But these stories are case reports, not formal scientific studies. Whether people improved because of better brain chemistry, and whether they'll live longer as a result, is any scientist's guess.

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The Anti-Aging Zone

Barry Sears

Regan Books, 1999

This decade-old book continues to attract followers. Sears first unveiled the Zone Diet -- a dietary approach to fighting heart disease and diabetes by optimizing hormone levels -- in his 1996 book "The Zone." In "The Anti-Aging Zone," Sears, a biochemist now widely known for his diet books, explains why the Zone Diet may be able to prolong life.

The diet is low in carbs and calories. Sears advises people to consume 40% fewer calories than normal: 1,200 a day for women and 1,500 for men. He says that the diet is calibrated to prevent hunger, malnutrition and declines in mental and physical performance. It's high in protein, rich in vitamins and minerals, low on starches and grains, and stresses low-glycemic vegetables and mono-unsaturated fats.

In "The Anti-Aging Zone," Sears attributes aging to excesses of insulin, blood glucose, free radicals and cortisol. The Zone Diet aims to keep levels of all four within a "zone": not too high and not too low. He advocates small meals and snacks throughout the day to help control insulin and blood glucose; reducing calories to cut consumption of free radicals; and lifestyle changes to control the stress that can stimulate cortisol production.

On a typical day, a Zone Dieter may eat a vegetable cheese omelet for breakfast, steak and vegetables for lunch, chicken and vegetables for dinner, and snack on ham-wrapped apple slices, wine and cheese. Moderate exercise helps keep insulin and blood glucose low, and meditation helps balance cortisol. Stick with it, Sears writes, and blood sugar will normalize, blood lipid levels will fall, stress and depression will diminish, and sexual function will return.