The publication earlier this year of Greg Crister's Eternity Soup: Dying for Eternal Youth as well as a big story in The New York Times Sunday Magazine last October have brought calorie restriction into the mainstream. Calorie restriction is a theory and practice of consistently and permanently eating an extremely low-calorie diet with the aim of extending one's lifespan.
Calorie restriction diets that aim to extend lifespan aim do so by consuming fewer calories than are needed to maintain normal weight, while still including all the nutrients and vitamins needed for good health. Most people who follow this diet eat 20 to 30 percent less than is normally recommended for their weight and age.
Proponents of calorie restriction contend that since processing calories uses energy, taxes organs, and creates cancer- and disease-causing free radicals; keeping calories to a minimum thus extends life. The easiest analogy is that our bodies are like cars and eating/digestion is like driving them – the less you run them, the longer they'll last.
The science behind calorie restriction is based primarily on animal studies. The theory, according to Crister, stretches back to the 16th century when the Renaissance humanist Alvise Corano posited that an extremely modest diet would lead to a longer life. His doctor recommended a simple diet because of symptoms that sound like type 2 diabetes. Corano ended up living to the age of 83 and credited his long life to his modest eating habits.
Modern and scientific studies cited by calorie restriction proponents have mostly been done on rodents. Mice fed a diet that reduced their calories by 30 to 60 percent from a young age increased their lifespan by 30 to 60 percent. Mice given a diet that reduced their calorie intake by 44 percent as "adults" lived, on average, 10 to 20 percent longer. Calorie restriction also seemed to lower cases of diabetes, heart disease, and cancer as well as decrease the rate of nerve damage from Alzheimer's disease, Parkinson's disease, Huntington's disease, and strokes.
The problem (or the good news if restricting less than 1,000 per day sounds more pleasant) with this theory is that it doesn't carry fully over to humans. The limited studies of calorie restriction in humans have found both positive and negative effects, and no evidence that it extends lifespan. According to the Mayo Clinic, the limited research that has been done on calorie restriction in humans has shown it beneficial in lowering blood pressure, controlling blood sugar and cholesterol levels, and (not surprisingly) maintaining a healthy weight. Yet seniors and leaner people are particularly susceptible to the ill effects of calorie restriction which include hormonal changes, reduced bone density, and a loss of muscle mass. Calorie restriction has been shown to cause depression, irritability, and lethargy.
Eternity Soup points out that there is a difference between lifespan and life expectancy. A lifespan is the maximum number of years that an organism can, with all things being optimal, live. While no one is sure about the true possible human lifespan, many agree that it probably hovers around 120 years. Of course, because of disease, lifestyle, and environmental factors, our life expectancy is nowhere near that and instead hovers in the 70s and 80s.
The possible benefits of calorie restriction become even murkier when one considers the emerging notion of longevity quotients, which is how long an animal lives relative to how long it should live based on its body size, all questions of optimal life span aside. Calorie restriction allows animals such as mice with low longevity quotients to reach their full lifespan. People already have a high longevity quotient, that is, we live longer than one might expect based on our size. The possible lifespan-enhancing effects of calorie restriction, following this logic, are minimal.
What is clear is that balanced modest diets – not restricted but not gluttonous either – have clear health benefits at every stage of life. The Balanced Care Method™ focuses on maintaining a lean body mass through a diet high in nutrient-rich, plant-based foods, regular physical activity, and eating until 80 percent full.
Corano, the Renaissance Italian who believed less food would help people live longer, believed the perfect meal was one of panatella, a soup made of rich chicken broth, bits of dried whole grain bread, a poached egg, and a generous spoonful of olive oil: Delicious, healthful, and a good addition to the Balanced Care Method™.
Panatella
This recipe is inspired by Corano's description of a good, simple meal. We've added a few vegetables to make it more Balanced Care Method™-perfect. This recipe makes one serving but is easily doubled, tripled, and beyond.
- 1 slice whole grain bread
- 2 to 3 cups reduced sodium chicken broth
- 1 tomato (fresh or canned), chopped
- 1 cup spinach or chard leaves, cut into ribbons
- 1 egg (optional)
- 1 Tablespoon extra-virgin olive oil
- Toast the bread. Tear or cut the toast into bite-size pieces and place in the bottom of a soup bowl.
- In a medium saucepan, bring the broth to a boil. Reduce heat to a steady simmer and add tomato. Bring broth back to a simmer and add the spinach or chard. Cook until spinach or chard is tender, about 2 minutes.
- Crack egg into soup and simmer, undisturbed, until cooked to desired doneness (about 3 minutes for cooked whites and a runny yolk, about 6 minutes for a set yolk). Use a slotted spoon to transfer egg onto toast pieces in the soup bowl.
- Pour broth and vegetables over the egg and toast. Garnish by drizzling with the olive oil. Serve hot.
