Longevity And Nutrient Sensing (Intermittent Fasting)

longevity and nutrient sensing

We all want to live as long as we can and in the best possible health far into our old age. Longevity on it’s own isn’t enough.

Now the talk isn’t just about lifespan. It’s about healthspan too.

Healthspan is an area of increasing scientific interest, with many ongoing studies into how to achieve great health for as long as possible.

One of the areas of interest is Longevity and decreased nutrient sensing, and the effect this can have on preventing disease.

It’s  becoming recognized that longevity does not have to result in poor health.

Many studies are now concerned with the link between low carb diets, fasting, and the prevention of disease

This is a very brief introduction to what is a complex subject. There are several links to the relevant studies, and you may want to follow with some more in depth reading.

This subject will be of special interest to anyone who is following a low carb or keto diet.

It has long been known that by adding intermittent fasting, these diets and their health benefits can be greatly enhanced.

Here you will find some information about the processes that are involved in this, and why it is so good for our general wellbeing.

The intention here is to enable you to become familiar with the fact that we have within our bodies three nutrient sensors which closely monitor our nutritional status.

This leads to the expression of a process which is both healing and able to prevent disease, with obvious consequences for both longevity and health as we age.

What exactly is nutrient sensing?

longevity and nutrient sensing

This it the ability of the body to sense the presence of nutrients.

The existence of nutrient sensors are important in any study of longevity.

When the body senses a lack of nutrients it signals a decrease in growth factor and an increase in autophagy.

We have evolved to be able to rapidly sense changes to our nutritional intake. This has important consequences for our survival.

If you’re not familiar with autophagy you can learn more here: The amazing benefits of autophagy and fasting .

The three most important nutrient sensors in the human body are:

  • Insulin ( sensitive to dietary protein and carbohydrates)
  • mTOR ( sensitive to dietary protein)
  • AMPK (sensitive to all nutrients)

Studies suggest that longevity can be enhanced when both Insulin and mTOR are blocked more than normal and AMPK is increased.

Why do we want increased AMPK?

longevity and nutrient sensing

AMPK is an enzyme that increases in response to a lack of nutrients.

AMPK is the energy sensor and when it increases it acts upon mitochondria. AMPK increases in response to a lack of nutrients.

Mitochondria are specialized structures unique to the cells of animals and plants.

They act as power plants, powering various functions of the cell and the organism as a whole.

The main function of mitochondria is to metabolize or break down carbohydrates and fatty acids in order to generate energy.

This study demonstrated that when AMPK increases, it triggers the generation of new mitochondria, and that renewal and recycling was also enhanced.

This was achieved in an animal study where the animals were subjected to intermittent fasting.

The study reported that these data demonstrate that mechanisms that promote mitochondrial homeostasis and plasticity can be targeted to promote healthy aging.

This is an animal study, but if the same pathway exists in humans, this study has major implications for the assumption that intermittent fasting could lead to longevity in people.

These findings  also sits well with what is already known about autophagy, and its benefits for health.

Decreased mTOR

longevity and nutrient sensing

mTor is comprised of two complexes. One of which, mTORC1 is controlled by glucose and protein.

When there is a lack of these nutrients, mTor is inhibited. This is demonstrated here .

When mTor is inhibited it triggers the process of autophagy.

Autophagy is desirable for many reasons including the fact that when mTor is activated too often it is associated with many diseases including cancer, see this study.

The study also showed that increasing mTOR activity was shown to drive cell cycle progression and increase cell proliferation mainly thanks to its effect on protein synthesis.

Moreover, active mTOR was shown to support tumor growth indirectly by inhibiting autophagy. Read more here.

Autophagy

There are three main types of Autophagy, and each is in involved in the eradication or engulfment of damaged cells or proteins.

They also deal with the engulfment of cytoplasmic material, eradication of pathogens and dealing with misfolded proteins.

All of which have amazing health benefits, for both existing disease and the prevention of future diseases.

Both of which have implications for not just longevity, but good health well into old age.

When mTOR is reactivated, autophagy is bought to a halt, and the body switches to concentrating on growth.

Decreased Insulin

longevity and nutrient sensing

Of all the processes discussed here, the effects of intermittent fasting on Insulin are probably the best known.

When insulin levels drop, this is one of the signals for autophagy to begin.

Levels of Insulin that are too high too often can lead to insulin resistance and can cause type 2 diabetes and a long list of other diseases.

Low levels of insulin will also inhibit the signal to store fat, see this study. This plays a big role in the prevention of obesity.

When insulin levels are constantly low this also acts to reduce our appetite, again helping to prevent unnecessary weight gain.

Obesity is now widely recognized as a major cause of many diseases and increased mortality.

Staying within a healthy weight is one of the biggest predictors of a long and healthy life.

Intermittent Fasting

longevity and nutrient sensing

One of the issues with the fact that calorie restriction leads to autophagy in people, is that it is not known if it is necessary to restrict all foods or just proteins.

If proteins need to be restricted,  it would then be necessary to know which proteins.

However, intermittent fasting has been demonstrated to stimulate autophagy by triggering a reaction in all three of the nutrient sensors.

Insulin is the first to react, quickly sensing the presence or lack of carbohydrates followed by proteins.

mTor appears to take longer, at about 15 – 30 hours and AMPK takes very much longer to increase in response to a lack of nutrients.

This would make evolutionary sense. We would need a well honed system of letting our body know when nutrients were short.

In our ancient past, this was something that happened frequently.

Our bodies developed a system whereby, in times of fasting, the body was able to switch from growth to repair. The biological equivalent of making the most of a poor situation.

Intermittent fasting is the main trigger for autophagy, if you’re interested to know more about other triggers read How to induce autophagy

Gene expression

longevity and nutrient sensing

During fasting there are several beneficial changes in many genes and molecules related to longevity and protection against disease.

Science is now at a stage where there is ever more knowledge of both the genetic and environmental factors which have been linked to unsuccessful brain aging.

This from the publication ” Unlocking the secret of longevity genes”

Evolutionary natural selection, the logic goes, has no reason to keep them working once an organism has passed its reproductive age. Yet we and other researchers have found that a family of genes involved in an organism’s ability to withstand a stressful environment, such as excessive heat or scarcity of food or water, have the power to keep its natural defense and repair activities going strong regardless of age.

By optimizing the body’s functioning for survival, these genes maximize the individual’s chances of getting through the crisis. And if they remain activated long enough, they can also dramatically enhance the organism’s health and extend its life span. In essence, they represent the opposite of aging genes–longevity genes.
When food is plentiful and we are eating enough, nutrient sensing pathways engage anabolism and storage.

However, times of scarcity and fasting act as triggers on the mechanisms of nutrient sensors such as insulin, mTOR and AMPK.

These nutrient sensors then mobilize mechanisms such as autophagy, which is the body’s repair and recycle button.

This process makes sense as we evolved at a time when the supply of food was intermittent.

It was beneficial for our bodies to concentrate on growth and nutrition when food was plentiful, but to switch off growth when there was not sufficient fuel for our immediate energy needs.

Autophagy is the process by which we can benefit from both feeding and fasting.

Autophagy is vital to our health and longevity.

It is now widely understood that the modern habit of eating too often prevents autophagy occurring as often as it once did.

Autophagy also naturally decreases as we age, and these two factors are implicated in many of the diseases that are associated with aging.

When insulin and mTOR decrease and AMPK increases in response to fasting, the process of autophagy is triggered.

This is the natural pathway to the body’s much-needed renewal and recycling processes.

For this reason, it is understood that one of the most important things that we can do for both our health and longevity is to control not just the type of food we eat, but also the timing of that food.

One of the best interventions against aging is intermittent fasting.

To read more see this study.

Intermittent fasting is showing itself as the trigger that allows us to not only live for longer, but to enjoy those extra years in the best possible health.

These articles may also interest you:

The amazing benefits of autophagy and fasting.

Seven benefits of autophagy and fasting.

How to induce autophagy

Intermittent fasting guidelines

 

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2 Comments

    • Hi Catherine,

      The evidence for fasting is overwhelming, it’s one of the most health promoting things you can do.

      However, science is still lacking on the amount of times you should fast, and the optimum time for autophagy to work it’s magic.

      There is some evidence that the benefits of fasting peak at about 36 hours, although I have seen 72 hours also suggested.

      Personally, I don’t see enough evidence to convince me to fast for longer than 3 days, and probably not more often than 2 or 3 times a year.

      The situation for intermittent fasting is somewhat different.

      Obviously intermittent fasting, especially 18/6 fasting can be done daily. There is a lot of science that shows how beneficial this is for both weight control and health.

      You’ll need to experiment, and find a daily eating window that suits you and your lifestyle. Somewhere between 6 – 8 hours of eating seems to be best, with the rest of the 24 hours fasting.

      It’s important to remember that fasting and triggering autophagy too often is not good for your health.

      There are many people who intermittent fast every day or a couple of times a week. They will then do a longer fast every four months. This seems to work well.

      I hope this helps, and if and when we see some more studies into the optimum amount of fasting necessary for health I’ll be writing about it here.

      Best wishes,

      Judy

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