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Caloric restriction, a diet that reduces calories without malnutrition, is a key player in the study of aging and longevity. This practice, often a significant but balanced reduction in calories, has been shown to extend life and health span across species from simple organisms to mammals. The mechanism is complex and involves metabolic regulation, stress resilience and cellular maintenance that slow down the aging process.
By triggering a cascade of biological changes caloric restriction optimizes energy use and repairs cellular components and puts the body in a state of longevity. This article, we will explore how manipulating dietary energy intake can impact the biological pathways of aging and what that means for a healthier longer life.
Caloric Restriction, Autophagy, and Longevity
Caloric restriction and energy deprivation are known in only a few instances for actually extending lifespan in most species. Caloric restriction lowers mTOR signaling which in turns upregulates other pathways of energy homeostasis such as AMPK and autophagy.
Autophagy and cellular turnover are required for life extension effects in DAF-2 mutants. Autophagy suppression does indeed negate the longevity effects of caloric restriction in other species as well. For example, if you block the autophagy genes in genetically modified mices’ then they won’t live longer even under caloric restriction, whereas normal mice who have autophagy activated do
So, the benefits of caloric restriction and fasting on lifespan are largely brought about by autophagy and sirtuin activity that promote cellular turnover and recycling of old cells.
That’s key because you can side-step some of the negative side-effects of prolonged caloric restriction by knowing what you’re doing and elevating autophagy with other means. In Chapter IV, we’ll examine this in greater detail.
Nematode Worms and Anti-Aging
Nematode Worms and Anti-Aging In 2017, a research paper appeared in the journal Cell Metabolism demonstrating that aging and age-related diseases accompany a decline in the cells’ efficient capacity to process energy [60] . Scientists manipulated the mitochondria of nematode worms who live for a short two-week span to conduct their experiment on longevity.
By restricting the worms’ calories and manipulating AMPK, they promoted longevity by maintaining mitochondrial networks and increasing fatty acid oxidation. This occurs in communication with other organelles called peroxisomes that regulate fat metabolism. Essentially, more fatty acid oxidation from their own energy stores led up to living longer because they were put under caloric restriction.
In short, caloric restriction encourages energy economy because the body must now maintain itself on concomitantly fewer calories. Unlimited energy supply, however, insists on mitochondrial inefficiency because every mitochondrion now must work less hard to carry its load so to speak. This can result in the storage of dysfunctional subunits. These pathways demonstrate that the mitochondria evolved to adjust to severe shifts in nutrient flux in the manner of fasting and feasting.
When food becomes sparse, the body enters a state of partial hibernation and repair so that it can survive until the next cycle when food is abundant and it is again a more favorable time to reproduce. Fasting and caloric restriction encourage mitochondrial economy by merging into one several mitochondria. Excess nutrients during the eating cycle fragment the mitochondria and reduce their capacity to generate energy.
Rats and Monkeys on Caloric Restriction
Caloric restriction and intermittent fasting have been shown to increase longevity before. Here are the main findings in other species.
- Rat Fasting Study (1946): A study on rats found that fasting one day out of three increased lifespan in males by 20% and in females by 15%. They didn’t experience any growth retardation but death of tumors increased in proportion to the fasting period. Other studies on rodents have shown reduced inflammation and other age-related diseases.
- Yeast Longevity: Fasting has been shown to increase the lifespan of bacteria and yeast by 10x. Yeast has a very short lifespan of just a few days and weeks but 10x is still impressive.
- Brain Neurons in Humans and Monkeys: Caloric restriction shows increased lifespan of brain neurons in both humans and monkeys. Maintaining brain health is key to longevity because you won’t be able to enjoy your life.
In 2009, a group of scientists from University of Wisconsin found biomarker and longevity benefits in rhesus monkeys who ate less. But in 2012, a follow-up study by National Institute of Aging found no improvement in survival but a trend towards better health. After going through the results, it’s thought that the different outcomes were due to several factors.
Does Caloric Restriction Truly Extend Lifespan?
Yes, many studies across many species from yeast to primates show that caloric restriction does work. It reduces metabolic rate and oxidative stress and delays the aging process and age related diseases. In short eating less makes your body’s maintenance systems work better and longer and potentially longer and healthier life.
What Health Benefits Does Intermittent Fasting Offer?
Intermittent fasting isn’t just about living longer; it’s also good for you now. That means better glucose regulation, stress resistance and fat metabolism. Some people even get mental clarity and focus. By fasting you’re giving your body a break to repair and clean out toxins so everything can run smoothly.
How does caloric restriction impact brain health?
Research shows that caloric restriction can extend the life of brain cells, which means better brain health as we age. This could be better cognitive function, lower risk of neurodegenerative diseases like Alzheimer’s and overall better mental health. The idea is that eating less wears less on your brain cells so they can keep functioning for longer.