What is the best diet for longevity? How can we stay healthy as we age? Are calorie restriction and fasting really necessary for living a long and healthy life?
In this article, we will discuss an alternative perspective on aging, one that is quite different from many of the “alternative health” longevity areas. There is currently no general consensus in the scientific community on aging, but metabolic rate certainly appears to play a role.
While some diet camps believe that you need to slow down your metabolism to live longer (vital force theory), the bioenergetics perspective, based on physiological principles, believes that speeding up your metabolism can prevent aging.
Life Rate Theory
The main idea behind the proposed “life-extending benefits” of calorie restriction and fasting is the “pace of life theory”: live fast and die young.
More specifically, organisms with a fast metabolism have shorter lifespans than those with a slow metabolism. So the idea here is to slow down your metabolism, like a slow-burning flame, to live longer.
Some examples of this mindset include:
- Because car parts break down over time due to use, we want to drive less.
- How many times does our heart beat in a lifetime? So let's slow down our heart rate and make it beat as long as possible.
One of the foundations of this line of thinking is the free radical theory. Aging is the result of the body's cells accumulating damage over time. The damage comes from free radicals, which are highly reactive atoms or molecules that are naturally produced in our bodies. Free radicals are produced during metabolism, so slowing down metabolism can decrease the rate at which free radicals are produced (and thus extend lifespan).
Unfortunately, this idea is based on studies of roundworms conducted in controlled environments. So can this idea be extended to humans in the real world?
As Balaban et al. note, “It is important to note that increased reliance on these alternative (backup) pathways can often result in energetically crippled but long-lived animals… Reducing an organism's reliance on these pathways may allow the worm to survive for long periods in a controlled laboratory environment, but in the real world, where only the fastest and most reproductively fit survive, these animals are likely to be at a significant disadvantage.”One
This free radical aging notion is one of the reasons some people promote calorie restriction for longevity.
Hayflick Limit
Another piece of evidence is something called the 'Hayflick limit', discovered in the 1960s.2,three The idea is that lifespan is determined by the limits of cell division, and cells can only divide a certain number of times, so we want to slow down cell division and reproduction. Unfortunately, these results are based on single cells in cell culture and are not based on in vivo data.
But many researchers are now questioning this notion of aging and the so-called “benefits” of calorie restriction.4,5,6,7,8,9 One review article presented a wealth of evidence that refutes the survival theory.10 Another study directly contradicts the survival claim, stating, “Individuals with higher metabolic rates have lower levels of reactive oxygen species in their bodies.”11
In fact, many researchers now worry that calorie restriction in humans may do more harm than good. One of the biggest criticisms of these survival theory studies is how they treat the control groups.
The experimental group eats a very restrictive diet, while in many studies the control group is allowed to eat as much as they want. The control group often eats much more than they would normally in nature. This makes it difficult to distinguish between the benefits of calorie restriction and the harmful effects of overeating large quantities of poor quality food.
“In recent years, Weissmann’s ‘wear and tear’ theory of aging and Pearl’s ‘life force’ theory have been clearly refuted by metabolic research showing that enhanced mitochondrial respiration reduces cellular damage and supports longer lifespan.” — Dr. Ray Pitt
It is well documented that long-term low-calorie diets result in a decrease in metabolic rate.12 Because the body slows down to conserve energy. So do we really want to slow down our metabolism to prolong our life? I don't think so.
A faster metabolism is linked to a longer lifespan
Evidence that contradicts the survival theory that there is a positive correlation between metabolic rate and longevity (i.e., faster metabolic rate means longer lifespan):
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Small dogs eat more food relative to their size than large dogs, and small dogs live much longer, sometimes twice as long, than large dogs.13 |
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Hamsters with a 20% higher metabolic rate live 15% longer than hamsters with an average metabolic rate.14 |
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Mice with a 30% higher metabolic rate lived 36% longer than mice with a slower metabolic rate.15 |
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Hummingbirds have one of the fastest metabolisms and live proportionally longer than other animals of their size.16 |
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Antioxidant supplementation does not increase lifespan (antioxidants reduce ROS levels). Genetic overexpression of key antioxidants does not lead to lifespan extension.17 |
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Naked mole rats, the longest-living rodents, have higher levels of oxidative damage than mice of the same age.18 |
Calorie restriction and fasting may have advantages over the Standard American Diet (SAD) when it comes to extending lifespan, but here's why:
- Restricting certain types of fat (polyunsaturated fatty acids – PUFA)
- Amino acid restriction that can cause inflammation if not balanced with glycine
- In our modern world, consumption of pollutants that have infiltrated our food system is decreasing.
A bioenergetic perspective on aging
The bioenergetic perspective is diametrically opposed to the life-rate theory, which sees aging as a result of a slowing down in metabolic rate.
Instead of a slow-burning flame (low metabolic rate), a high metabolic rate continuously renews the organism due to higher ATP production. With sufficient energy production, the organism can maintain proper structure and therefore function properly.
When energy production is disrupted (metabolic rate is reduced), the body does not get enough energy to maintain proper structure and function.
The idea is that the system can recover and repair very quickly by mimicking the metabolism of a child that is functioning optimally. Aging is a slowing down of metabolism. And aging can be reversed by improving metabolism.
Optimal levels of T4 and T3 appear to be correlated with greater robustness and improved functional capacity in centenarians.19 Since the thyroid is the main regulator of metabolism, you cannot have good thyroid function without a strong metabolism. If the body is given two choices:
- Calorie restriction/fasting/carb restriction
- Eat healthy foods rich in vitamins and minerals needed for energy production regularly.
Which option would your body thrive on? Option 1 might be better than the standard American diet, which is loaded with processed, funky foods, but humans will not thrive on calorie restriction. End of story. Nature thrives on abundance!
Minnesota Starvation Experiment
In the Minnesota Starvation Experiment, subjects consumed 1,500 to 1,600 calories for five to six months (i.e., they were in a calorie deficit for a period of time).20 Sure, I lost weight, but it had many negative health effects! Here are some examples:
- Metabolic rate and body temperature decrease
- Increased edema rate
- decreased libido
- Loss of muscle mass
- Reduced size of various organs in the body, such as the gastrointestinal tract, heart, and liver. (How can a liver that has shrunk by 50% function properly? It can’t! One of the slow consequences of the liver is that it cannot detoxify properly, which leads to a buildup of toxins and an increased risk of aging.) And many more.
(If you’d like to learn more about the Minnesota Starvation Experiment and its morphological, psychological, and biochemical consequences on the human body, check out our in-depth podcast series here!)
The better your energy metabolism, the better your body functions and the slower your aging process. And you can't have a strong metabolism if you chronically undereat (as some diet camps recommend)!
Lessons from Centenarians
Centenarian diets vary greatly… but when we study centenarian reports and diaries, we find some commonalities.
• They don't get too stressed or worried. Living in a stressful situation is a surefire way to accelerate aging, because it interferes with your ability to produce energy properly. But dealing with stress properly takes energy! So having enough energy reserves through a well-functioning metabolism will help you cope better with stress.
• They eat real whole grains regularly. You rarely hear of centenarians who say that fasting or a ketogenic diet is the secret to their longevity. Instead, they prioritize whole grains and do not restrict their food intake too much. You will see reports of many centenarians eating chocolate and ice cream regularly, if not daily!
(memo: High-quality chocolate and ice cream made with good ingredients are good food! Chocolate is rich in saturated fat, and real ice cream is made with a few ingredients: cream, milk, egg yolks, sugar/honey/maple syrup. Unfortunately, many options sold in stores these days may contain vegetable oils, gums, or other additives.)
• They lived happy and fulfilling lives doing what they loved!
Points to take
So does this mean that you can eat whatever you want without feeling stressed? No! It is important to be mindful of the quality and source of your food. The standard American diet (SAD), which is rich in PUFAs, is clearly not effective. Life expectancy is decreasing.21 Despite the fact that we have both “advanced” biotechnology and medical services.
But SAD is quite different than it was 100 years ago, and one of the biggest dietary changes is the type of fat we consume. Polyunsaturated fats (PUFAs) make up a much larger portion of our diet today, due to the introduction of vegetable oils (seed oils) and confinement of livestock on high PUFA diets.
Image from Frontiers in Nutrition, January 13, 2022. Section: Nutritional Epidemiology.
Unfortunately, the metabolites of PUFA oxidation cause a number of systemic inflammations, and studies have shown that activation of the “master” inflammatory factor (NF-kB) can lead to premature aging.22
Of course, you should eat real food, exercise, and move regularly! But you don’t have to go to extremes to achieve optimal health. Strict fasting regimens, eliminating entire food groups, or extremely low-calorie diets are not the “key” to optimal living.
Instead, eating, living, and exercising in a way that increases your metabolic rate will ensure that your body has the high levels of ATP it needs to maintain proper systemic function.
And in a previous article, I explained how to easily assess your metabolic rate at home using body temperature. There is no one-size-fits-all approach to improving your metabolism, but here are some tips to get you started:
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Eat enough calories to meet your needs (chronic intake of 1,600 calories can be detrimental to your health) |
Minimize your PUFA consumption |
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Eat enough carbohydrates and choose carbohydrate sources that work for you. |
Eat foods rich in glycine (such as bone broth) regularly. |
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Cook most of your meals yourself |
Strength training to build muscle |
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Reduce stress in your life where you can |
Pursue joy and creativity |
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Maintain meaningful relationships |
About the Author
Ashley Armstrong is the co-founder of Angel Acres Egg Co., specializing in low-PUFA (polyunsaturated fat) eggs that ship to all 50 states (join the waitlist here) and the co-founder of Nourish Cooperative, which ships low-PUFA pork, beef, cheese, A2 dairy, and traditional sourdough to all 50 states. Waitlist will be opening again soon.
