Bob Cavanaugh smokes five cigars a day. He typically sports a mighty tan and has a sweet tooth the size of Montana. These aren't the typical characteristics of a 61-year-old who plans to live to be 120, but Cavanaugh has a secret weapon: he practices severe calorie restriction.
For years there has been evidence that a diet extremely low in calories extends the life span of species from mice to monkeys (and a recent study confirms positive results for humans on this type of diet too), and the more we learn about caloric restriction, the more it appears to be something of a medical marvel: this week, a study in the journal Science shows that monkeys on a 20-year calorie-restricted diet not only lived longer, but had younger brains and fewer age-related diseases than the monkeys that ate a regular diet. But is it possible to eat a low-calorie diet and not lose your mind? Cavanaugh says yes.
Yes, the diet is by definition restrictive (thought practitioners simply call it CR).
Men consume 1,800 calories, rather than the recommended 2,500; women eat only 1,500 to 1,700 calories per day, compared with the recommended national average of 2,000. But that doesn't mean they don't eat well.
On a recent morning, Cavanaugh, who lives in coastal North Carolina, prepared his breakfast, the same one he has had most days since starting the calorie-restrictive diet eight years ago: a quarter cup each of oatmeal, oat bran, powdered skim milk, and liquid skim milk. After two minutes in the microwave, he topped the concoction with half a cup of frozen blueberries—to provide antioxidants and improve mental crispness—and two tablespoons of sunflower seeds that will fulfill 60 percent of his daily vitamin E requirements. He washes down his 451-calorie breakfast with a cup of coffee. He won't eat again until dinner and claims he won't be hungry until then.
"My breakfast gives me more than half my nutrition for the day," says Cavanaugh, who's pre–calorie restrictive eating habits included bacon and eggs, hot dogs, chips, and cinnamon buns. "It's so filling, I just don't get hungry for lunch."
A retired Marine who stands 5 feet 10 inches tall, Cavanaugh eats has seen positive physical results since he scaled back his calorie intake. Prior to embarking on the diet, he weighed 178 pounds, had a body mass index of 26 (an ideal BMI falls between 18.5 and 24.9), and his cholesterol level was 273 (the ideal is less than 200).
Five months into his new lifestyle, Cavanaugh's cholesterol dropped 103 points, and his triglycerides dropped from 145 to 63 (a healthy number is 150 or below). Now 140 pounds, he claims he hasn't had a cold in eight years, and the chronic athlete's foot and jungle rot he suffered since his time in the Marines has disappeared completely. His energy levels have skyrocketed. "Remember when you were a kid and you would suddenly just take off running across the yard because of the exhilaration of energy? That exhilaration came back to me," Cavanaugh says. "I haven't felt like this since I was a teenager playing tackle football."
The benefits of a calorie-restricted diet were first seen in 1934 when a group of researchers at Cornell University observed that the lives of rats extended by 33 percent when the rodents' calorie intake was restricted. Results were first seen in humans almost by accident. In 1991 eight scientists entered a man-made, materially closed ecological system in Tucson, Ariz., known as Biosphere 2 to study man's influence on the ecosystem. The biosphere was unable to produce as much food as the scientists had predicted, forcing the researchers onto a nutrient-packed, extremely low-calorie diet. Roy Walford, the group's physician and an expert in calorie restriction and aging, noted that despite weight loss, the group's mental and physical activity levels were excellent; their blood pressures and cholesterol levels dropped.
A 2004 study published in the Proceedings of the National Academy of Sciences detailed the results of humans who have practiced the calorie-restriction diet for a long period of time. The study's subjects had lower cardiovascular risk factors and extremely high levels of HDL (or "good" cholesterol), and triglyceride levels were comparable to or lower than Americans in their 20s, despite the fact that all the study's participants were between the ages of 35 and 82.
Still, the mechanisms behind the diet's success are still unknown. One general theory is that the diet puts the body into survival mode, causing cells to be extremely efficient, boosting the process by which cells remove damage. Research has shown that these unrecycled or damaged cellular components can lead to age-related decline.
Despite the positive results of this study, caution is advised before jumping into the CR diet. "You need to make sure you do things properly," says Bonnie Taub-Dix, registered dietitian and national spokesperson for the American Dietetic Association, who says issues of malnutrition are a concern. "Even then, it's not a guarantee of living longer. Some people eat lousy diets and have great genetics; others take good care of themselves but have poor genetics. One plus one doesn't always equal two."
Although Cavanaugh is very careful about his nutritional intake, he'll occasionally give in to his sweet tooth, or he and his wife will splurge on dinner out—though he says a steak, which he occasionally enjoys, "just tears my stomach up" due to the high fat content. He still eats birthday cake (400 calories) at his grandchildren's parties, a glass of red wine (124 calories) with dinner "six nights out of seven," and every Thursday he can be found sipping a beer with his friends down at the local cigar bar.
The rest of the time, dinner typically consists of a small portion of lean meat, chicken or fish; a big salad; and fruit and yogurt for dessert. After, Cavanaugh eats his two daily canned oysters to supply the zinc and copper he needs and a handful of nuts, including two Brazil nuts to provide selenium.
Then he and his wife head to the porch. They smoke and watch the sunset. "I used to think about life as being on a conveyor belt. You got on and traveled to the end, then died. But when I got into learning more about CR, it changed my whole outlook on life," he says. "I still see it as a conveyor belt, but now I know that I can regulate the speed of it. I can slow it down. Living to be 100 is now a definite goal."