Low-Calorie Diet Q+A

Researchers say humans may be able to extend their life span by severely limiting caloric intake while packing in the nutrients. What's it like to try this type of nutrition plan?

Paul and Averill McGlothin shared their experience on 20/20 and are answering questions from ABCNEWS viewers regarding their nutrition choices. For more information, contact the Calorie Restriction Society at www.calorierestriction.org

Question: How do you handle hunger? Small meals often, snacking or what?

— Alyce Ann Jula Aber Hamburg

Answer: We accept occasional hunger as part of this lifestyle. The hunger sensation is not extreme, and it makes us glad: it's a signal that we are doing what we intend — eating less fuel than our bodies might crave, so we are more likely to attain our health and longevity goals. We definitely like it better than the bloated feeling of being satiated. Another cause for joy is that when the body is fed fewer calories than it "expects," it goes looking for more. That takes the form of the cells' digesting inclusions that they "didn't bother with before." This results in a clean-up, a sort of cellular level detox. We love it! Our bodies are so smart.

Q.: How do you maintain a low weight, yet still consume enough calories to sustain an exercise program? Also, what research has been done to link the benefits of CR with taming Multiple Sclerosis (MS), which I was diagnosed with 11 years ago.

— Cathy

A.: An intake of 1,800 calories is plenty for me to sustain my (Paul's) weight at my level of exercise activity. I weigh myself regularly and if my weight slips lower than my target of 131, I increase my caloric intake until my weight is stable. I run about 60 miles per month and weight lift. While the CR lifestyle appeals to me, I don't think I would be consuming enough calories to remain strong while exercising.

There are all levels of CR, so it's not necessary to restrict like we do to get some benefits. Studies show that CR gives far more longevity benefits than exercise, though, so we personally follow a moderate exercise program — making it easier to sustain my limited calorie intake.

We don't have an answer for you about MS but recommend that you keep an eye on the work of researcher Mark P. Mattson. His work on Brain Derived Neurotrophic Factor may be especially interesting. Searching on multiple sclerosis and BDNF in www.Pubmed.gov (the National Library of Medicine's online access) ought to be useful. It turns out that a discussion is at this moment going on about MS and CR on http://calorierestriction.org/. We're wishing you the best.

Q.: Will you be telling the viewers what foods you eat to maintain good health; do these foods satisfy hunger; and, do you exercise regularly? Thank you.

— Suzanne Lexington, Ky.

A.: We eat nutrient-dense food choices, such as protein (salmon, chicken, whey, brewers' yeast, etc.) and low glycemic carbs (cabbage, broccoli, collards, and the like), as well as fruit (kiwis, oranges, for example) and fats (egg yolk a couple times a week, walnuts daily, olive oil, etc.) These foods satisfy hunger when eaten, but we do get hungry, and that's when we know that our bodies are detoxifying themselves at the cellular level. We exercise moderately on a daily basis (run-walk) and more vigorously twice a week for aerobics and weight training.

Q.: While on this diet, did you experience any light-headiness or dizziness? Did you feel more tired than usual? How long were you on this diet and did you lose weight?

— Isabel Columbus

A: We have been living this healthful lifestyle for about 10 years. We have not experienced any light-headedness or dizziness. Rather than feeling more tired, we have more energy.

Yes, weight loss is virtually universally experienced when fewer calories are consumed than the body would normally use. And we're talking about a 25 percent - 30 percent reduction in intake. If you are interested in more detail, the Calorie Restriction Society is an organization of people, most of whom are CR practitioners, who exchange information about the process and how it works. (http://calorierestriction.org/)

Q.: Did you lose any muscle mass?

— Steve

A.: No, I have gained muscle mass because I exercise with that in mind: maximum strength training per muscle group only once per week and careful choice of optimal amino acid sources like whey protein. True, I might have gained more muscle if I were not on CR, but my fitness goal is optimal function not muscle size.

Q.: What are the effects of this diet upon a person's mental abilities? Does a slower metabolism correlate to a lesser mental ability, or lesser problem solving skills?

— Geoff Haisty Raleigh, NC

A.: As we told the interviewer, there is no "this diet," rather there are many different ways to approach CR. My experience has been improvement in mental capabilities.

Some of the most dramatic improvement came when I integrated limited daily fasting into my CR regimen, meaning that in addition to limiting calories, I also spend a significant time away from food-finishing a very small, easily assimilated dinner at say 5 PM and not eating again until 6 or 7 in the morning. On weekends I stretch the fasting period even longer to maybe 8-10 a.m.. Exciting research by Mark Mattson at NIA labs has shown that such fasting provokes secretion of neuroprotective chemicals involved in protecting and regenerating brain cells. (Search on Mattson M in www.Pubmed.gov to review his work.

Q.: What's the difference between this "diet" and semi-starvation?

— Amy O'Donnell Marque TX

A.: Semi-starvation is depriving your body of what it needs. We are giving our bodies what they need to function optimally. Our interest is to nourish ourselves as close to optimally as we can using foods with a high deliciosity index. We measure food, track the components and experiment with spicing. We eat proteins and fats relatively sparingly, and it does take a lot of nutrient-dense vegetables and fruit to add up to enough calories even for us. We should rush to assure you that this attention to detail is not necessary to gain real benefits from CR. Optimal health-and-nutrition is our hobby, and you will find almost as many versions of CR practice as practitioners. A good place to learn more is http://calorierestriction.org/.

Q.: Would you recommend teenagers to maintain a low-calorie diet? If so what would be best the best way for one to go about this?

— Jessica Newport

A.: The research is not yet definitive on how early it is advantageous or safe for a person to begin CR. So while it is probably good for everyone to eat in moderation, one should be careful about restricting calories during the teen years when the body is still growing. Note that we describe our diet as calorie restricted NUTRIENT-dense. We would recommend that anyone include high quality foods in their diet like sweet potatoes, broccoli, and other yummies, which offer benefits at any age.

Q.: How does one start on a low-calorie diet? Is it a gradual process? Where can I get more information?

— Toni Loftin Austin, Texas

A.: We recommend reading Roy Walford's latest book, Beyond the 120-Year Diet. Here you will find all the info necessary to intelligently and safely follow a nutrient dense, low-cal diet. Another very useful resource is the Calorie Restriction Society. You can learn about the Society and its information exchange at http://calorierestriction.org/. Yes, gradually is the safest way. Try to integrate the dietary changes into your lifestyle over a period of a year or more.

Q.: How long have you been doing this? Did you make any other lifestyle changes at the same time or since you began? How much has your weight changed? How energetic do you feel? Describe any effects, good or bad, that you think can be ascribed to this diet, and explain why. Probably what you eat has changed as well as how much. Can you comment on separable effects and interactions? How feasible would you consider a vegan version of the diet?

— Robert Atlas Austin, TX

A.: We've been practicing some degree of CR for about ten years. Other lifestyle changes that we've adopted in that period and practice to some extent include meditation, the Alexander Technique, Feldenkrais, the Sedona Method. Both of us have better energy than ever, better recall, lower blood glucose, more gradual blood glucose rises, and reduced levels of many hormones. Our dietary practices also include an effort to control glucose, using the glycemic index of foods. We are currently eating less protein than we used to because research shows that protein restriction has similar effects to calorie restriction. A vegan diet is very feasible and there are many members of the Calorie Restriction society who are vegans. Our particular approach does include small amounts of animal protein: salmon, white meat of chicken, egg whites for example. We also eat an egg yolk a couple times a week, especially for the cholesterol, which our bodies' need and which is not found in plants.

Q.: What is meant by "extreme Caloric Restriction"? How do you define this and what is the target? I have seen definitions such as 15-20% lower than your set weight or the weight you were at when you were in your 20s. But that seems vague. Using the BMI a score of between 19 and 19 put you at underweight. Can we use the BMI to set a target?

— Andy Lefebvre Warren, MI

A.: We are serious but not extreme. Our caloric intake is about 20-30% reduced from that of an average person for our heights. Probably, national averages are too high anyway because so much of our society suffers from obesity. CR is not really about losing weight but maintaining a comfortable weight where you can eat the fewest calories. If you get too slim, you will actually need more calories to maintain your weight than if your weight loss is moderate. Our favorite, calorie restrictor, Ralph, is almost 101 and at 5'10" and 157 lbs eats only 1000-1200 calories a day to maintain his relatively high (compared to most calorie restrictors) BMI. We'd recommend losing weight slowly and when you find you can maintain a weight that allows you to restrict calories at 20-30% of normal for your height, consider stopping there.

Q.: I've recently lost 20 lbs. by using the Weight Watchers diet. How do I go about getting the nutrients that I need and how do I know I am getting the right amount?

— Matt Fury A.: Congratulations! Track your intake with a software program designed for that purpose. By doing so you will learn a great deal about choosing the best foods and the right amounts for you. Some of the best packages are Dr Roy Walford's Interactive Diet Planner (www.walford.com) NutriBase Nutrition Software (www.NutriBase.com).

Q.: I take a multi-vitamin that supposedly has 100% of what I need but does my body absorb these well enough?

A.: It's impossible to answer the absorption question without a thorough assessment of your digestive and intestinal health. Progressive laboratories like MetaMetrix Clinical Laboratory (www.MetaMetrix.com) provide expert testing and analysis. Work with your doctor on this.

Q.: What are the 5 best vegetables to eat? Less calories with most nutrients.

— Allison Hummer Amherst

A.: Spinach, collards, kale, broccoli, and turnip greens are our favorites for low calories and high nutrients. Lightly steamed sweet potatoes, a bit higher in calories, are another nutrient-dense favorite. Lots of other veggies are excellent. Which ones we want to eat, when, and in what amount depends on whether we are looking for something to support our immune systems, whether we are looking for more fiber or less, what other nutrients we've had that day, and of course which wonderful flavors we want to enjoy. We use nutritional software to help us decide our menus. Two of the best packages are Dr Roy Walford's Interactive Diet Planner (www.walford.com) NutriBase Nutrition Software (www.NutriBase.com).

Q.: I was just wondering how this diet is affecting your blood sugar? I get really shaky and feel very week if I don't have carbohydrates. How do you have the energy to get anything done and not feel hungry all of the time? What is the secret? Do you eat every two hours? Is this working for you? Do you feel better in general and are you losing weight? Are you taking certain supplements to help with the food reduction? — Rowena Kerby Lubbock

A.: Our blood sugar is on the low side in the 80s or 90s after meals and in the 70s after fasting overnight. Note that because our bodies have adapted to these lowered glucose levels we rarely have the low blood sugar feelings many people experience.

We select foods that are low-glycemic choices like salmon, nonfat yogurt, steamed sweet potatoes, cauliflower that provide a slow steady source of glucose when digested. We avoid foods like white potatoes that provide a rapid influx of glucose into the bloodstream. For a thorough list of foods and their glycemic ratings as well as in-depth info on this subject, log on to Rick Mendosa's Web site (http://www.mendosa.com/). This definitely is working for us. We feel better in general. We are not losing weight now, though we weigh less than when we started. We take nutritional supplements, trying for a full spectrum of vitamins and minerals at 100% RDA instead of mega-doses. We eat carbs, proteins, and fats for every meal except dinner, when we don't eat concentrated protein. For lunch especially, we are concerned about giving ourselves a protein bias for focus and concentration, so our first lunch course will be something like salmon, chicken or egg whites. We space the courses out so that we can get the effect we want. We are following (in www.Pubmed.gov) the research of Mark P. Mattson at NIA in Bethesda with great interest. His work shows that the body's time away from food may be as important as the reduced amount of food. So we are timing our meals so that we have 14-16 hours between dinner and breakfast. This is relevant to the present question because we continue to work productively during that period, so my guess is that our bodies are processing food and specifically glucose differently from yours. That may not be very helpful, but I think that all the calorie restrictors I know have designed different programs — ones that work for them individually.

To that very point, some of the testing that has been most helpful to us is MetaMetrix's ION (Individualized Optimal Nutrition) Profile: http://www.metametrix.com/Testing%20Services/Special%20Profiles/ION/