Back in the 1930s, Dr. Clive McCay was the first to publish data showing that rodents appear to age more slowly and live a lot longer when their food intake was restricted.1 Since McCay?s research in rodents, many other species of animals have been subjected to calorie restriction. In every case, the animals fed 25-40% fewer calories than control animals have been shown to live significantly longer. They also appear to age more slowly.2 The anti-aging impact of reduced calorie intake does not appear to be related to the ratio of carbohydrate, fat and protein in the diet.3 Of course, the amounts and types of fats, proteins and carbohydrates in the diet do impact disease processes like atherosclerosis and coronary heart disease.
Recent studies in dogs and monkeys kept on calorie-restricted diets also show that they appear to age more slowly and experience favorable alterations in biological markers of aging and disease.4 Biological markers for aging that have been shown to improve on calorie-restricted diets include lower body temperature and serum insulin levels. Higher levels of the hormone DHEAS are also associated with slower aging. These same biomarkers of aging in animals have been shown to be associated with increased longevity in men.5
While it seems likely that calorie restriction may very well slow the aging process and increase the life span of humans, it is very difficult to restrict calorie intake, as it leaves most people hungry and often obsessed with food. Researchers recently compared various risk factors for atherosclerosis in a group of 18 subjects who are practicing calorie restriction (CR) and age-matched healthy controls. Table 1 shows the average differences in a variety of risk factors for atherosclerosis. The CR subjects had a markedly reduced risk for atherosclerosis. In addition, the researchers also examined the thickness of the carotid arteries, which are the arteries in the neck that supply blood to the brain. They found no evidence of thickening in any of the CR subjects and the walls of their arteries were about 40% less thick than the arteries of the comparison group. While the results of this study do not prove the CR subjects are aging more slowly than the comparison group, the results certainly demonstrate that their risk of dying from cardiovascular disease is markedly lower. The proportion of the improvements seen in these CVD risk factors that was due to CR and how much might have been caused by a lower intake of saturated fat, hydrogenated fat, cholesterol and salt is difficult to say. This is because the published data did not provide quantitative data on the intake of these and other dietary components, like fiber intake, known to impact risk factors for atherosclerosis.6
The bottom line
It is best to eat more high-satiety foods like fruits, grains, beans and whole grains with a high fiber and water content. This is because these foods will provide more satiety per calorie. This allows calorie restriction and loss of body fat while minimizing hunger. The people who were on the CR diet had an average BMI of 19.6 and about 1/7th the abdominal fat of control subjects; see charts below.
By James Kenney, PhD, RD, LD, FACN.
1. J Nutr 1939;18:1-13
2. Aging Clin Exp Res 2001;13-261
3. J Gerontol Biol Sci 1988;43:59-64
4. J Nutr 2003;133:2887-92
5. Science 2002;297:811
6. Proc Nat Acad Sci. 2004;10:6659-63
Judy’s passion for cooking began with helping her grandmother make raisin oatmeal for breakfast. From there she earned her first food service job at 15, was accepted to the world-famous Culinary Institute of America at 18 (where she graduated second in her class), and went on to the Fachschule Richemont in Switzerland where she focused on pastry arts and baking. After a decade in food service for Hyatt Hotels, Judy launched Food and Health Communications to focus on flavor and health. She graduated with Summa Cum Laude distinction from Johnson and Wales University with a BS in Culinary Art, holds a master’s degree in Food Business from the Culinary Institute of America, 2 art certificates from UC Berkeley Extension, and runs a food photography studio where her love is creating fun recipes.
Judy received The Culinary Institute of America’s Pro Chef II certification, the American Culinary Federation Bronze Medal, Gold Medal, and ACF Chef of the Year. Her enthusiasm for eating nutritiously and deliciously leads her to constantly innovate and use the latest in nutritional science and Dietary Guidelines to guide her creativity, from putting new twists on fajitas to adapting Italian brownies to include ingredients like toasted nuts and cooked honey. Judy’s publishing company, Food and Health Communications, is dedicated to her vision that everyone can make food that tastes as good as it is for you.