The CR Diet
Tools and Resources for the Calorie Restriction Diet

How do you start a CRON diet?
Although Caloric Restriction with Optimum Nutrition (CRON) has been shown to extend the maximum life span of many species, the diet has to be started cautiously. People who start calorie restriction with great zeal often worsen their health instead of increasing their longevity. A high degree of calorie restriction without adequate monitoring of nutrition can result in nutritional deficiencies, loss of bone mass or osteoporosis. Here are some general recommendations about how to start a Calorie Restriction diet:

1. Read Dr. Roy Walford's book Beyond the 120-year diet - How to double your vital years. This book describes the scientific principles of the CRON diet, including how to select nutrient-dense, low calorie foods.
2. Schedule a medical exam. Get some lab tests to establish a medical baseline including lipid panel, CBC, blood pressure, bone density, etc.
3. Join the Calorie Restriction Society. This will give you access to support from many members who can answer your specific questions.
4. Start using nutrition software to analyze your food so that you can learn to optimize what you eat. You don't have to start a diet, but you have to start measuring and weighing what you eat. By tracking your nutrition you will learn how many calories you are consuming on a daily basis, and you will identify any nutritional deficiencies.
5. Concentrate on Optimum Nutrition. Try to devise daily menus that meet 100% of the RDA of all vitamins and minerals. Get your nutrition from foods rather than supplements.
6. Exercise 30 minutes per day with emphasis on strength-building exercises, but don't overdo it to avoid getting injured.
7. Use the Calorie Restriction Calculator to determine the number of calories required to achieve 5% Calorie Restriction. Start with a 5% CR diet, but make sure that you still achieve Optimum Nutrition.
8. Once you are familiar with measuring your food and optimum nutrition, you can gradually reduce your calories, but you should probably not go below 16% CR.

Risks of CR
The amount of food in rodent experiments is usually restricted by 30% or 40% starting shortly after weaning. At maturity, animals restricted by 40% weigh only half as much as the unrestricted controls, but they live approximately 30% longer. Several studies have determined that sudden implementation of severe calorie restriction shortens life instead of extending it. Humans usually start CR in adulthood after achieving a normal height. Humans who practice CR are usually thin because CR does not reduce the size of the bones or the height. Low calorie diets, unless properly implemented, may not contain sufficient nutrients to maintain a healthy body. Some human practitioners of CR have reported decreased bone density and osteoporosis.

Calorie Restriction should not be confused with anorexia nervosa which is a psychological eating disorder characterized by an obsessive fear of gaining weight. A few CR practitioners allow their Body Mass Index (BMI) to decrease into the range typical for anorexia, but they monitor their nutrition carefully. Most people practicing CR have a Body Mass Index in the lower half of the normal range (18.5 to 24.9). White blood cell levels usually decrease during CR, and medical professionals unfamiliar with the effects of CR may assume that this is a pathological condition. It should be obvious that extreme CR without adequate safeguards can result in malnutrition or death by starvation.

Calorie Restriction with Optimum Nutrition (CRON)
Calorie Restriction involves only the reduction of calories. Calorie Restriction with Optimum Nutrition (CRON) requires selecting low-calorie, nutrient-dense foods that contain 100% of the Required Daily Allowance (RDA) of protein, essential fatty acids, vitamins, and minerals. Since the number of calories depends on the activity level, active persons need to consume more calories than sedentary persons. The implementation of a CRON diet requires accurately measuring and weighing foods, and using nutrition software to assure that the diet contains 100% of all nutrients. Learn how to count calories.

Books about Calorie Restriction

• Roy Walford, M.D.,
  Beyond the 120 Year Diet : How to Double Your Vital Years
  This book, often referred to as BT120YD, describes the fundamental principles of the CRON diet. Dr. Walford was a pioneering researcher in the anti-aging field, and he was also a participant in the Biosphere II experiment which provided a lot of data about the physiological effects of human CR.
  
  
• Paul McGlothin, Meredith Averill,
  The CR Way: Using the Secrets of Calorie Restriction for a Longer, Healthier Life
  This is one of the latest books about the practice of Calorie Restriction. The book describes some of the benefits of maintaining low blood glucose levels. Paul McGlothin is Vice President for Research and Director the Calorie Restriction Society, and Meredith Averill is in the Board of Directors. There is a web site associated with the book: Living the CR Way (www.livingthecrway.com). In their web site, Paul and Meredith market subscriptions to The CR Way to Happy Dieting, and promote workshops to learn about Calorie Restriction and about choosing foods that improve your health. The CR Way diet tries to obtain the longevity benefits of calorie restriction that are regulated at the cellular level. The diet is based on the metabolic efficiency that results from the physiological changes caused when the body tries to cope with food scarcity. These changes protect against disease and slow the aging process.
  
  
• Brian M. Delaney, Lisa Walford,
  The Longevity Diet: Discover Calorie Restriction--the Only Proven Way to Slow the Aging Process and Maintain Peak Vitality
  Brian M. Delaney is the President and Director of the Calorie Restriction Society. Lisa Walford is the daughter of Dr. Roy Walford, and Director Emeritus of the Calorie Restriction Society. The book describes the benefits of CR, includes comments from CR practitioners, and provides recipes for typical CR dishes.

Nutrition Software
There is a variety of software for tracking nutrition. Some programs reside in your own computer and offer privacy but little portability, whereas other programs are available online and make the data available at home, in the office, or while traveling. What you choose will depend on your personal preferences and the features that you find most useful.

• CRON-o-Meter
  CRON-o-meter is a free, open-source, Java-based desktop program written to meet many of the requirements of persons on a CR diet. The program features pie charts showing the proportion of macronutrients (protein, fat, carbohydrate), and bar charts for the percentages and amounts of nutrients in the diet. The program runs on Windows, Linux, and Macintosh computers. CRON-o-Meter is also available as a web application that can be accessed from mobile devices.
  
  
• FitDay
  FitDay.com provides a free online diet journal to track foods, exercises, and weight loss. Over 2 million members use the site to monitor their diet and their weight.
  
  
• NutritionData
  NutritionData.com provides a suite of online tools to analyze your diet quickly and easily. You can save, edit, and manage the foods you eat most often. You can also analyze recipes, and log the foods that you eat to track the nutritional value of your diet. One of the most valuable tools of this web site is its Nutrient Search interface that makes it possible to find foods with the highest or lowest concentrations of specific nutrients.
  
  
• DWIDP
  Dr. Roy Walford's Interactive Diet Planner (DWIDP) is a downloadable nutrition tracking program that is available to supporting members of the Calorie Restriction Society. The program runs on Windows systems only. A free demo version is available at www.walford.com.
  

Calorie Restriction Calculator
Whereas nutrition software is used to determine the proportions and kinds of foods needed to achieve 100% of all nutrients for a specific caloric intake, the Calorie Restriction Calculator is used to estimate the number of calories required to achieve a specific level of Calorie Restriction. The CR Calculator calculates the Basal Metabolic Rate (BMR) for a person identical to you but with a Body Mass Index in the middle of the normal range. Since there are no experimental controls for human CR, the CR Calculator provides an objective method for estimating a reference value to determine the percentage of Caloric Restriction.

Other diet calculators and web pages:

1. Body Fat Calculator - Calculates percent body fat using the Navy circumference method.
2. Macronutrient Calculator - Helps to calculate the weights and percentages of protein, fat, and carbohydrates, including fiber, for a diet.
3. How to Count Calories - Explains how to measure food and how to use nutrition labels to count calories.
4. USDA National Nutrient Database - Search the USDA database to get nutrition information about food items.

CR Community
These are organizations and online groups that discuss Calorie Restriction.

• Calorie Restriction Society
  The Calorie Restriction Society, now called the CR Society International, is nonprofit 501(c)(3) corporation dedicated to understanding and promoting the Calorie Restriction (CR) diet. The CR Society provides basic information about practicing CR, runs several email groups, acts as a contact point for anyone interested in CR, pursues basic research in CR through long-term human studies, and organizes regular CR Conferences. A basic membership of the Calorie Restriction Society is free and it allows participation in the list discussions that cover many aspects of the latest scientific research in longevity science.
  
  

CR Supplies
Warren Taylor's store - Features artificial sweeteners (sucralose, neotame), bulking agents/fiber (guar gum, konjac powder, baker's micronized cellulose), flavoring oils, defatted cocoa. The fiber products are used to provide satiety for low calorie diets and diminish hunger.

CR Blogs and Web Sites

• CRON Diary by Mary Robinson - Discussion of the CRON life style by a long-time practitioner.
  
• Matthew Lake's Calorie Restriction blog. Through the practice of calorie restriction Matt hopes to be alive when there are true anti-aging therapies available so that he can live even longer. Matthew also has a YouTube channel that features several CRON videos.
• CRON yogitect - Blog by Arturo Veve featuring ashtanga yoga, calorie restriction with optimal nutrition (CRON), Zen Buddhism, and architecture.
• CRON-IC - A blog by Drew Patterson with an emphasis on the need for long-term commitment to Calorie Restriction to obtain real health benefits.
• Bob Phillips' Calorie Restriction web site. Bob is an active back-packer and runner who started practicing CR in 2004. His web site features many scientific references about the benefits of CR.
• Fight Aging - A non-profit organization that encourages the development of lifestyles and medical technologies to extend the current limits of mortality. Topics include Anti-Aging, Calorie Restriction, Cryonics, and Negligible Senescence.
• Zenpawn Vegan food blog - Erin Dame's blog featuring information about vegan CRON lifestyle. Erin markets vegan recipe books through his web site.
• Jeff Novick's blog - Jeff is a nutritionist who practices vegetarian caloric restriction. Jeff's blog discusses food choices, labels, pesticides, and other interesting topics. He offers his professional services through his web site, and lectures about nutrition. Some of his presentations are available on DVD: Lighten Up - Weighing In On The Weight Debate