Seventy-five years of research shows that dietary restriction (DR) is the one tried and tested means to extend lifespan and to improve many markers of health.
One form of DR is a calorie-restricted (CR) diet with optimal nutrition. The idea is to provide adequate nutrition with the least amount of calories (in other words, under-nutrition without mal-nutrition). Intermittent fasting (IF) is another form of DR. Intermediate fasters eat about the same amount of calories as non-fasters on a carefully restricted schedule. This implies that the episodic deprivation, irrespective of the caloric count, produces the physiological effects of IF.
In almost every species studied, including yeast, fish, rodents, dogs, and primates, DR seems to mysteriously slow aging, extend youth, and postpone diseases associated with old age. In laboratory experiments, some animals have been able to expand their healthy life spans by up to 400% with optimal DR.
The rationale behind the DR theory of longevity is that organisms become stronger and more resistant to diseases in response to the stress of a continual state of mild hunger. Some scientists believe that this could have been an evolutionary adaptation, which allowed our ancestors to survive periods of food scarcity.
The physiological effects of IF and CR are similar. Both CR and IF prompt cells to set up defenses against stress, which protect against aging and degenerative diseases. However, since IF fasters are allowed to eat as much as they want when given access to food, IF is usually more appealing than the continual self-denial of CR.
Many mechanisms of DR induced life extension have been proposed. One of the most prominent is the discovery that DR up-regulates autophagy, or what is called the repair mechanism of the cell. This effect is related to the down regulation of insulin and insulin-related molecules.
Studies indicate that insulin’s role as the body’s blood sugar regulator is simply a consequence of its major role of regulating cellular reproduction, and therefore lifespan. Insulin -predominantly secreted in response to dietary carbohydrates- signals to the body that it is well nourished and conditions are prime for cellular reproduction. On the other hand, when insulin level is low, the body senses famine, down-regulating reproductive pathways and up-regulating cellular maintenance and repair.
The beneficial effects of DR are plenty. They include:
-Prevention of Alzheimer’s Disease
-Improved learning and memory (via increased brain derived neurotrophic factor, BDNF)
-Lowers body mass index (BMI)
-Cardio-protective effect (protects heart and brain cells against injury and improves outcomes in stroke and myocardial infarctions; increase levels of circulating adiponectin).
-Less expression of age markers in the liver and brain
-More youthful appearance
-Resistance of neurons in the brain against excito-toxins
-Prevention of mitochondrial fatty acid oxidation under stress
-Reduced vascular endothelial (inner lining of blood vessel) damage
-Reduce oxidative stress
-Less chance of developing/improvement of diabetes, cancer, heart disease, brain degeneration
In a word, dietary restriction (DR) creates physiological changes that slow down aging and protects against age-related diseases. It is now known that these effects are related to insulin and that reducing insulin secretion plays a major role in extending life.
Therefore, one must learn to efficiently burn foods that do not provoke insulin secretion – fats. Fats are stable, slow burning sources of energy that do not create advanced glycation end-products and that naturally satiate. They have many roles in the body and are the only macromolecules that can carry the fat-soluble vitamins that build healthy bone, teeth, and nervous system. Some fats are essential and therefore must be supplied by the diet regularly.
On the other hand, carbohydrates provoke insulin secretion, have a very limited structural role, are glycating, and can only briefly satisfy the appetite. The body has multiple ways to manufacture them from amino acids and parts of fat (gluconeogenesis).
It is also important to consume enough high-quality, complete protein to meet the body’s daily requirements. Amino acids are required to make enzymes, antibodies, clotting proteins, hormones, transport proteins, muscle, hemoglobin, and other cellular components. However, protein intake beyond the amount required for cellular building, repair, and maintenance up-regulates an important kinase called mammalian target of rapamycin (mTOR). mTOR is a highly conserved enzyme that synthesizes the messages from various pathways that feed into it to regulate cellular growth, proliferation, survival, metabolism, and angiogenesis.
The signaling pathways upstream of mTOR send activating or inhibitory signals based on the presence or absence of nutrients, growth factors, hormones, and oxygen. When protein (and insulin) is in high supply, mTOR is up-regulated, which may accelerate aging and cancer development. mTOR signaling is the focus of current longevity and cancer research.
So how many calories should one consume to reap the benefits of DR? It depends. Age, level of activity, sex, BMI, quality of diet, and level of health will determine what one’s body is able to tolerate. As a general rule, adjust the caloric intake to meet the body’s most basal needs. Calorie restricted (CR) diets usually reduce calories by about 30%.
Here are some guidelines:
- There are multiple permutations of intermittent fasting (IF). For instance, every other day (EOD) fasting is a cycle of 24 hours of fasting followed by 24 hours of not fasting. Eating only one meal a day is another form of IF.
- Carbohydrate-laden foods, like bread, pasta, grains, and sugar, provide very little nutrition, are poorly sustaining, and provoke the secretion of insulin. Cut out the calories from easily digestible carbohydrates because humans have no dietary requirement for them. Moreover, a carbohydrate-based diet drives obesity, high blood pressure, diabetes, and metabolic syndrome.
- Replace the carbohydrates with enough fats in the diet to provide fat-soluble nutrients and long-term satiety.
- Eat nutrient dense foods such as grass-fed/wild organ meats, wild fish, seaweeds, wild foods, dark green vegetable juices, grass-fed butter, etc.
- Include plenty of antioxidants in the diet. Antioxidants have been shown to enhance the anti-aging effects of DR.
- Eat just enough high-quality protein to meet your daily needs (usually about 50-60 grams a day according to the DRI).
- Supplement with anti-glycating nutrients (Vitamin B6, R-alpha lipoic acid, acetyl L-carnitine, L-carnosine).
Combining DR with optimal nutrition can be very powerful. By consuming a nutrient dense diet and learning to burn fats instead of carbohydrates (ketosis), one can obtain maximum benefits from DR without much will or suffering.
1.”Cardio-protective effect of intermittent fasting is associated with an elevation of adiponectin levels in rats” (The Journal of Nutritional Biochemistry, May 2010).
2.”Fasting Away Disease? Intermittent Eating Seems To Fight Diabetes” (Psychology Today, July 1, 2003).
3.”The fast route to a longer, healthier life” (New Science Magazine, May 2003)
4.Primal Body-Primal Mind (Gedgaudas)
5.”Short-term calorie restriction reverses vascular endothelial dysfunction in old mice by increasing nitric oxide and reducing oxidative stress” (Aging Cell, January 2010)