"Hunger for the Glorious Future!"
The promise is tantalizing: Eating dramatically less could add decades to our lives and mitigate everything from cataracts to cardiac disease. But are the daily hardships worth the potential payoff?
I'd start chopping on Sundays. Whole cantaloupes, strawberries, spinach, green peppers--everything I planned to eat during the week ahead. Standing in front of the sink, I'd scrape carrots and scoop out melons while trying to avoid the lettuce draining in the colander. Then I'd start slicing, often nicking my fingers with the knife. Next, another step I despised: measuring. If I wanted blueberries in cottage cheese, I had to measure one-third cup (30 calories). Honeydew melon for lunch? Then dice exactly four ounces (37 calories). As I sliced eight-inch celery stalks (7 calories each), I felt like the speaker in T.S. Eliot's poem, "The Love Song of J. Alfred Prufrock," who measured out his life with coffee spoons.
Three hours later--when my baggies were packaged and I had fished the last renegade grape from beneath the stove--I would ask myself why I endured doing something I hated so much. As I put away the food and closed the refrigerator door, I saw the answer: a snapshot of me and my CRONies.
One year ago, I learned about a diet that could double our longevity and cut our chances of developing everything from cataracts to dementia. The diet, known as caloric restriction (CR), requires eating dramatically less--from 30 to 50 percent fewer calories--for the rest of your life. The payoff, at least according to animal studies, looks promising. Studies have shown CR to preserve bone mass, immune function, and skin thickness, while offering the body better resistance to toxic chemicals and traumatic injury.
But there is a downside. CR leaves most people perpetually hungry, physically cold, and even sexually impotent. If eating substantially less equaled many extra years of such side effects, would people follow the diet? Would living longer and healthier make the hardships worth it? I wanted to focus on caloric restriction for my master's thesis in science writing at Hopkins, so I decided to put myself on the diet for one month; I planned to cut my daily caloric intake by 30 percent to 1,120 calories. For support and information, I turned to a devoted group already practicing the diet. They call themselves CRONies (for calorie-restricted optimal nutrition), and belong to the CR Society, an Internet listserv through which they share advice, discuss problems, and offer encouragement--such as the widely circulated poem, "Cheat Death":
BE HUNGRY, and smile.
BE COLD, and rejoice.
SUFFER NOW, and smile again.
Life ends too soon.
Cheat death you skinny rascal.
IT'S WORTH IT!!
To date, no scientific study has proven the diet will work in humans, because developing such long-term studies would prove nearly impossible. The closest that researchers have come is to study our distant relatives--rhesus monkeys. "The manifestations of aging are very similar," says Donald Ingram, Hopkins adjunct professor of psychology, who has researched aging and CR for two decades. "Like us, these monkeys develop cancer, diabetes, and some aspects of Alzheimer's disease as they age. The females even go through a menopause." In 1987, Ingram, along with researchers George Roth and Mark Lane from the National Institutes of Health (NIH), began work on the very first CR study in nonhuman primates. Headquartered at the Gerontology Research Center on the Hopkins Bayview Campus, the group began studying some 150 rhesus monkeys at a lab in Poolesville, Maryland. The goal: to confirm the results of earlier studies that showed CR to be effective in rodents.
In fact, the effects of CR have been documented since 1935, when Cornell scientist Clive McCay unexpectedly discovered that rats eating less lived nearly 30 percent longer. Over the years, researchers have tested the diet in everything from water fleas to fish. In each study, the animals ate the same foods, but only those in the control group ate as much as they wanted. The others were given between 30 and 50 percent fewer calories. To keep the animals healthy, researchers added vitamins and minerals to their diet. Every study showed that animals eating less lived up to twice as long. The average life span of protozoa increased from 7 to 13 days, spiders from 50 to 90 days, and guppies from 33 to 46 months.
The studies also confirmed that animals on restricted diets lived longer than any animals of their species. Calorie-restricted protozoa, for instance, reached a record age of 25 days--12 days older than the previous record. This was an amazing discovery because extending maximum life span has never been easy. Since the days of ancient Rome, the average human life span has jumped from 22 to 74 years, but our maximum life span hasn't budged. It's still about 110 years. The only way to push this limit is to slow down how quickly humans age. To age more slowly, the entire life span--youth, middle age, old age-- must be stretched out. Researchers had no idea how to do that until McCay discovered caloric restriction.
Because primates live a lot longer than protozoa, Ingram's research won't be finished for at least another decade. So far, the results look promising. "The rates of age-related chronic diseases and mortality are about half in the calorie-restricted group," Ingram reports. "I'm fairly convinced CR is a beneficial treatment of aging. Intuitively, I'm fairly convinced that the diet will work in humans."
Preliminary results from two other primate studies--one led by gerontologist Richard Weindruch at the University of Wisconsin-Madison, and the other by Barbara Hansen at the University of Maryland-Baltimore--match those from the NIH study. "We've seen fewer signs of diabetes and arthritis and less free radical damage in restricted muscle among our 39 monkeys on CR," says Weindruch. Just how, and why, does caloric restriction work? Currently, some researchers are looking at the body's oxidation process. When the power plants in our cells, known as mitochondria, release the energy from food, they produce free radicals--damaging unpaired electrons that can react with fats, proteins, and nucleic acids to set off everything from cancer to vascular disease. Perhaps, the thinking goes, calorie restriction both decreases the production of free radicals and helps the body to better ward off their negative influence.
Other scientists, including Lane and colleagues at the NIH, are examining the body's insulin response to glucose, which is produced in our bloodstream after we eat carbohydrates. Normally, insulin carries off the blood sugar for safe storage in fat and muscle cells. But our cells get resistant to insulin with age and obesity, thus allowing glucose to build up in the bloodstream. By joining forces with collagen and other proteins, excess glucose can damage nerves, organs, and blood vessels. Lane looked at older animals on CR and found high insulin sensitivity, low glucose, and the good health enjoyed by younger animals.
|"I caught myself staring at other people while they ate. When a stranger saw me watching him take a cough drop from his pocket, he asked, 'Are you OK?'"||
Buoyed by such findings, I ate my last cheeseburger, then
headed off to the grocery store to load up on fruits and
vegetables--foods that contain nearly every vitamin and
mineral I would need to stay healthy.
My first day on the diet was a piece of cake. That morning, and every following morning, I made a list of everything I'd eat for the day. Breakfast: half a cup of cottage cheese and an orange (167 calories), lunch: a protein bar, an assortment of vegetables, and eight ounces of honeydew melon (299), and dinner: a large salad with olive oil and a chicken breast (290). I treated my leftover calories as insurance. Whenever I felt hungry but didn't want a meal, I'd snack on fruits or vegetables.
I've never been a fan of spending hours following recipes, so I opted for quick meals that could be fixed in 10 minutes. The CRONies, I quickly discovered, preferred more complex food preparation. "Sherm's Megamuffins," a popular recipe I never made, has 27 ingredients, including calcium and zinc supplements that must be crushed, sunflower seeds that must be ground, and everything else that must be tossed in a blender. The recipe, which goes on for pages, ends with a note: "[The muffins] taste better after freezing and microwaving than they do when eaten hot out of the oven."
By the end of my first week, I had developed food rituals. Every morning after breakfast, I'd tell myself I couldn't have lunch earlier than noon. When I started feeling hungry around 11 o'clock, I'd drink several glasses of water. And I began eating only pieces of things. At a Super Bowl party, I split a much-coveted oatmeal cookie in half and gave the other half to my friend. While he devoured his half in two bites, I savored mine for 15. To be on the safe side, I threw away any leftovers before I found myself eating more than I had intended. When I didn't have the willpower to resist second halves or fourths, another force--God? my subconscious?--intervened: The morning I gave in to a glazed doughnut (190 calories), half of it flew out of my hand uncontrollably and fell to the ground.
I soon learned something that the CRONies had already come to know: All strategies to eat less--whether chewing gum, eating quarts of sugar-free Jell-O, or keeping the names of dead friends in the candy jar at work--eventually fail. Take the low-calorie Cool Whip I bought to jazz up my sugar-free gelatin. The first few nights on the diet, I topped my dessert with just two tablespoons (25 calories). On my fifth night, I found myself standing in the kitchen eating Cool Whip right from the container. In minutes, half the tub was gone (325 calories). But compared to other CRONies, my Cool Whip binge seemed insignificant, as I learned from listserv posts like this one, from Norm Goldstein, who eats around 1,500 calories a day. "Yesterday," he confessed, "I binged on the worst junk possible--potato chips, cookies, ice cream. I probably ate around 3,500 calories."
One week into the diet, I started feeling fidgety and restless an hour after eating. I'd feel dizzy and see everything in a blur. Concerned, I e-mailed the CR Society to find out if anyone else suffered from excess energy. Several replied affirmatively. One man wrote that his restlessness has lasted 14 years, while another said he felt it for about nine months, during the time he lost most of his weight.
In the research lab, this restlessness is called "semi-starvation induced hyperactivity." Researchers working with rats on calorie-restricted diets noticed that those eating less daily ran between 2.8 and 5.3 miles more than the other rats. Some of the rats on restricted diets ran themselves to death.
Despite the possibility of dying from too much energy, I looked forward to my hyperactivity. So did other CRONies. Warren Taylor wrote, "Eat less, and feel more energy. Fast, and feel great." I eventually counted on being restless, and channeled my excess energy into running errands, cleaning, or exercising.
But along with feeling physically edgy, I became an emotional mess. A trivial comment or incident could leave me on the verge of crying. One noon, I couldn't find my lunch in the office refrigerator, and when I thought about someone else eating my chopped carrots and 20 grapes, my eyes teared up. I found myself thinking of nothing but food--the melon and celery lunch that awaited me, the cheesecake party I would host to celebrate the completion of my diet. I caught myself staring at other people while they ate. When a stranger saw me watching him take a cough drop from his pocket, he asked, "Are you OK?"
My preoccupation with the diet and its lifestyle, it turns out, were par for the course. Some days, I received more than 50 individual messages from CRONies, each one going on in detail about some specific part of the diet. "Sometimes when I read the CR digest I want to bury my head in a bag of Cheetos," wrote one CRONie. "I realize we are talking about matters of life and death, but we're all flirting with obsession."
Flirting is an understatement. Most CRONies seemed married to CR. They bought countless diet guides, calipers to measure body fat, and huge pots and pans to accommodate large recipes. They kept track of nearly every calorie and nutrient they consumed and spent hours every day replying to each others' messages. Didn't these people have anything better to do?
Apparently not. I did ask them in an e-mail if they had other hobbies. Some replied, listing bicycling, backpacking, playing sports, and reading diet books. Before starting CR, few smoked, drank alcohol, or ate red meat; many were of average weight and had always been avid exercisers. After starting CR, some stopped consuming any foods made from animal products and even fructose, the natural sugar found in fruit. Although some CRONies couldn't run marathons anymore because they weren't eating enough calories, nearly all have added more weight-bearing exercises to their routines. Keeping toned, one man noted, helps avoid the "concentration camp victim appearance." And very morning, CRONies measured body fat, cholesterol, blood sugar, and blood pressure. Many CRONies, I learned, take self-administered IQ tests to monitor their thinking skills, which appear to improve for animals on caloric restriction. Mine seemed only to diminish.
Taylor repeats to himself every night, before going to bed, "Hunger for the glorious future." This mantra, he said, helps him avoid a bedtime snack and reminds him of what he lives for. Taylor, who grew up in Vermont and now lives in California, also tells himself that he likes feeling cold, a side effect of long-term caloric restriction. "From my childhood conditioning, things like the numbness of my hands don't bother me. And shivering is exciting, as long as you are very active and busy!"
Given such obsessive responses, I sometimes felt like caloric restriction could easily cross the line into an eating disorder, such as anorexia nervosa. In fact, says Angela Guarda, director of the eating disorders clinic at the Johns Hopkins School of Medicine, "Anorexia is extreme caloric restriction." Those with the eating disorder typically eat just 500 to 1,500 calories a day, she notes. They obsess about weight and exercise, have an aversion to change, rarely engage in impulsive behaviors, and enjoy working toward distant goals. As they progressively cut calories, "they develop an intense preoccupation with food and complex rituals that prolong eating." Hmmm ... all of this was starting to sound uncomfortably familiar.
Despite what appear to me to be striking similarities between the CR lifestyle and a life-threatening eating disorder, CRONies are quick to point out the key difference: nutrition. Roy Walford, a 77-year-old pathologist at the University of California-Los Angeles who has studied the life-extending diet for 30 years and followed it for decades, says, "The goal of caloric restriction is undernourishment, not malnourishment. You have to eat foods dense in vitamins and minerals."
But many researchers remain dubious. Ingram and others I spoke with emphasize that they do not recommend people follow caloric restriction, especially severe CR, because the long-term effects and safety of the diet have not been documented in humans. "If a person attempts 20 to 40 percent caloric restriction, the odds are they're getting on the wrong side for any of a zillion nutrients," says Weindruch from the University of Wisconsin-Madison. Ingram adds: "You'd have to be under a physician's supervision to make sure you don't dip into malnutrition."
|"Twenty-three days into the diet, I stopped counting calories. I had lost only four pounds."||
Less than two weeks into the diet, after offering to make
tea for a few visiting friends, I told them I felt more like
a whiskey. We went to a local pub, and I ordered two
glasses. I didn't care if the drinks put me over 1,120
calories. After a few sips, I felt like myself again.
Becoming an alcoholic CRONie, though, was not an option. For the next week, I continued to eat less and suffer more. As I struggled, the grocery store ran out of celery and my friend Penny told me she didn't want to be around me because of my moods. I couldn't cope.
Twenty-three days into the diet, I stopped counting calories. I had lost only four pounds, far short of the CRONie body type ideal. "If you don't look sort of starvation type ratty with your clothes off, you are nowhere near the borderline of safe CR," Taylor advised. CRONie Michael Sherman, who weighs 122 pounds after three years on the diet, said, "People think I have a serious illness."
It turns out that achieving this look can wreak havoc on your sex life. In a recent CR Society poll, 14 out of 26 men who had been on the diet for more than six months reported being less interested in sex. (Women reported similar experiences.) "If you go on CR that is very strict ... you will duplicate the effects of castration. You will be neutered, and you will know it," said Taylor. To my surprise, CRONies, as well as their partners, seemed to adjust. One wrote, "My wife and I have reduced our sexual frequency from approximately weekly to approximately fortnightly to accommodate my lower libido." Some said eating an extra 100 calories twice a week increases interest. Others said more cholesterol or Viagra does the trick.
Toward the end of my diet, I told the CR Society, "The promise of living until I'm 130 years old is too far away to keep up the lifetime routine of taking my own food to parties and telling myself I don't need to eat when I want something." No one responded.
"Is caloric restriction for everyone?'" asks Gaston Bathalon, an NIH nutritionist investigating dietary restriction in humans. "No." Children, for instance, should never follow the diet because it could stunt their growth by up to 10 inches. Some studies also show that caloric restriction may not benefit older animals.
But what about people in their prime? "There are probably some personality types who will be more likely to stick with caloric restriction," says Jeremy Walston, a researcher in geriatric medicine at Hopkins. Recently, he and Hopkins colleague Ross Andersen submitted a proposal to the NIH to study the feasibility of humans following the diet. In addition to measuring physiologic markers such as insulin sensitivity and metabolic hormone levels, their study would investigate who might be most likely to follow the diet and what percentage of caloric restriction could be maintained. The results, Walston says, could guide the design of long-term studies. At press time, funding for the proposal was still pending.
Hopkins's Ingram, who lasted only two weeks on the diet, says, "With poor compliance over a lifetime, our alternative strategy now is to create 'CR mimetics.' " The goal: to fake cells into thinking that not enough energy is available for normal cellular processes.
When an energy source, food, is scarce, an animal's body will use what energy is available to maintain overall health. (Think of a hibernating bear.) The physiologic result is lower body temperature, lower glucose and insulin levels, and slower metabolism--all protective effects you get with caloric restriction.
With CR mimetics, animals don't need to face a food shortage to use energy differently. Instead, a chemical compound reduces the cells' use of glucose. So, even though an animal eats as much as it wants, the animal's cells function as if energy is scarce, thus activating any number of protective mechanisms.
In collaboration with George Roth and Mark Lane from NIH, as well as Mark Mattson, a Hopkins neuroscience professor and chief of the Gerontology Research Center Laboratory of Neurosciences, Ingram has tested a compound called 2-deoxyglucose on rats and mice and, most recently, rhesus monkeys. The compound mimics the beneficial effects of CR, such as longer life, without bringing about many of its negative ones, such as extreme weight loss. Initial findings, however, revealed that high doses of the compound are toxic. Though lower doses appear beneficial, Ingram thinks other compounds might be more effective at mimicking caloric restriction. The results of his research will be published in Scientific American within the next year.
For those who want to start caloric restriction now, we can have our cake and eat it too--by practicing 10 percent restriction. It appears that even this moderate restriction can also extend life. Walford, who compared the life spans of fully fed mice to those on 10 percent CR, found the calorie-restricted mice lived five months beyond the typical 38-month life span.
Following 10 percent restriction would be relatively easy. All I would have to do is drink water instead of soda or use sugar-free jelly instead of peanut butter. Without the hardships of a stricter diet, I could enjoy my life now and in the years to come. Eat a little less, and live a little longer. That's what I'm doing now.
Emily Carlson (MA '01) is a science writer at the University of Wisconsin-Madison.
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