Lisa Walford, coauthor of The Longevity Diet (Da Capo 2010), curriculum director YogaWorks Teacher Training

Shortly after being diagnosed HIV positive in 1985, Lisa Walford decided to adopt the calorie-restriction (CR) plan pioneered by her father, Roy Walford, MD. She lived medication free for the next 15 years. Today, the energetic 56-year-old follows a basic medicine regimen, but says her healthy, disciplined diet and her daily yoga practice not only continue to help stave off AIDS and its related health issues, but also make her feel young and vibrant.

Among the many strategies for living longer and avoiding disease, CR has perhaps the strongest scientific backing: more than 1,000 animal and human studies conducted during the past 80 years. Research shows cellular benefits from calorie restriction start to kick in with just a 10 percent cut. The hypothesis is that as calories are reduced—repeatedly exposing cells to mild stress—the body experiences what scientists call a hormesis effect:
a generally positive adaptive response.

“The body believes it has an inadequate amount of food so it goes into more of a survival mode, where it strengthens its defenses at a metabolic level,” Walford says.

You can approach a CR diet in a variety of ways. Walford began by cutting her daily calorie intake by about 10 percent—the difference in eating full-fat dairy products versus low-fat, swapping green tea for juice or soda, and skipping meat once a week. Simply focus on nutrient-dense foods like fruits and vegetables that are naturally high in nutrients and low in calories. There’s no rigid eating plan. Some people graze on small meals throughout the day; others, like Walford, prefer to stave off hunger by eating a protein-packed meal in the middle of the day, for example, 2 ounces of baked tofu with steamed vegetables in tomato sauce. Over 12 years, she gradually cut her calorie intake by 20 percent; she’s quite thin but has a clean bill of health, including low cholesterol and normal blood pressure and glucose levels.

CR diets may cause side effects, including bone thinning and lower libido in 10 percent to 15 percent of people. Some people go too far and get too thin, Walford cautions, and may get heart palpitations. (CR also isn’t recommended for children, people with eating disorders, or pregnant women.) To keep bones strong, eat calcium-rich foods like dark leafy greens; supplement with calcium, magnesium, and vitamin D; and do weight-bearing exercises such as walking and weight lifting, says Walford. She also recommends 15 minutes of meditation and 30 minutes of yoga poses daily. “Yoga makes me more sensitive to the effect that everything has on my health,” she says.