By Dr. Joseph Mercola
with Rachael Droege
<!-- #EndEditable --->
Numerous studies have shown that lowering your caloric intake may slow down aging, reduce age-related chronic diseases and extend lifespan. The effects have been observed in a variety of species from worms and yeast to rats and fish, and while it is uncertain whether long-term calorie restriction has the same effect in humans, preliminary evidence suggests that it does.
What is known is that calorie restriction reduces metabolic rate and oxidative stress, improves insulin sensitivity, and alters neuroendocrine and sympathetic nervous system function in animals, as noted in a review in the American Journal of Clinical Nutrition. The mechanism behind these effects is not known, but I suspect the majority of the benefits from calorie restriction are related to its influence on insulin, as reducing calories also reduces insulin, a major accelerant of aging. Insulin also affects many bodily systems, all of which could potentially affect longevity. Insulin:
- Alters the expression of numerous other hormones
- Stimulates the sympathetic nervous system
- Promotes vasoconstriction
I do believe that eating less is likely to be healthier for us in the long run, as controlled energy restriction is the only regimen that has been shown in the laboratory to increase lifespan, and therefore may be a foundational requirement for proper diet. Calorie restriction is not the same thing as dieting or starving yourself, however, so please realize that this can't be done without wisdom as human populations that consume low-calorie diets that are restricted in protein and micronutrients have:
- Short stature
- Late reproductive maturation
- Suppressed ovarian function
- Impaired breastfeeding
- Impaired fertility
- Impaired immune function
Fortunately, many of the above side effects can be avoided by using more nutrient-dense food sources. This is one of the reasons why the juicing program works so well. It provides relatively low-calorie, dense nutrition that does not raise insulin levels. Another great whole food option is whey protein concentrate , which provides dense nutrition with low calories and a minimal insulin response, and is very convenient for those who are often on the go.
Calorie restriction won't work if you aren't getting enough vitamins, minerals and other nutrients that are necessary to keep your body functioning properly. Inadequate nutrition will result in malnutrition and a worsening of health. So if you do decide to control your calories, make sure that every calorie you eat comes from a nutrient-rich food source.
It isn't necessary to use an all-or-nothing approach to calorie restriction as studies have shown that minor to moderate calorie restriction can result in some health benefits also. It appears that the more calorie restriction, the greater the health benefits, unless you become undernourished.
While an extreme calorie-restricted diet is not appropriate for some people, merely cutting out junk foods and soda, which are virtually all high in calories, could result in moderate calorie restriction and provide a great deal of health benefits. Occasionally skipping lunch or eating smaller meals, especially when only unhealthy foods are available, is also likely to provide some benefit.
If you are interested in this way of eating, check out my nutrition plan for advice on foods that are rich in nutrients and health-promoting properties. Please note that calorie restriction is not appropriate for children under the age of 21 years, pregnant or nursing women, or women who are trying to conceive.
Interestingly, it is thought that exercise may also create a "relative" calorie restriction as exercise produces many of the same benefits such as:
- Improved insulin sensitivity
- Decreased fat mass (FM)
- Reduced cancers
When you think of calorie restriction, think of minimizing your intake of calories and harmful substances while maximizing your intake of nutrients. Anyone who tries calorie restriction should carefully monitor their health and watch for potential side effects such as decreased bone density, feeling faint or overly fatigued, decreased mood or sex drive and an increased sensitivity to cold temperatures.