Willa Mag

There are still many unsolved mysteries in science. For example, what is dark matter? Why do we have consciousness? Are we alone in the universe? But for the average adult, no question is more vexing than this one: Why do I always feel so tired?

This question is of crucial importance, especially since a recent analysis of data from 32 countries showed that as many as one - fifth of healthy adults complain of severe fatigue. Persistent tiredness is one of the most common reasons for seeking medical advice, so common that medical staff often abbreviate it as TATT (Tired All The Time) - perhaps to conserve their own energy. Usually, there is no obvious medical explanation for fatigue, and doctors can offer little help beyond blood tests to rule out common nutritional deficiencies.

Despite the huge impact of fatigue on our overall health, until recently, the medical community had surprisingly little research on the concept of "having energy". Filling this gap is the multi - trillion - dollar wellness industry, which offers a variety of supplements, special diets, and lifestyle adjustments that claim to boost our energy.

However, scientists are now re - examining what it really means to be "energetic" or "tired" from a brand - new perspective. Research shows that our perception of this state largely depends on the brain's continuous assessment of the energy available to cells. This discovery is changing our understanding of overall health, providing new ideas for the clinical treatment of fatigue and revealing practical ways to help us relieve energy depletion.

It seems unreasonable that many otherwise healthy people still feel tired. At least in Western societies, most people can easily access far more calories than they need. If "feeling energetic" were simply a matter of the relationship between calorie intake and energy expenditure, we should all be full of vim and vigor.

So, why isn't this the case? The short answer is that the energy we feel - our "subjective vitality" - isn't as simple as a fuel gauge. Instead, it's a continuous assessment by the body - brain system of the energy available in the body, including how much energy is currently available, how much has been allocated for use, and whether there's any remaining energy to handle upcoming tasks.

This feeling is an example of interoception, which is our ability to sense internal signals from our bodies. These signals tell us how well we're adapting to the external environment. When something goes wrong - like when the body senses a lack of energy - these signals prompt us to take action to solve the problem. Research on interoception shows that our emotions, feelings, and motivations actually stem from a continuous and ever - changing dialogue between the body and the brain.

Viewing "energy" from this perspective can explain why replenishing energy isn't just about eating more food or spending money on some trendy supplement. The key is to identify which part of the body - brain dialogue is sending the signal to "conserve energy" and take corresponding measures to address the issue.

The problem could lie in the mechanism of cellular energy release, or it could be that the brain anticipates an upcoming physical or psychological challenge and deliberately holds back some energy. Or perhaps certain factors, such as stress or the immune system's fight against infection, are consuming a large amount of the body's resources. Whatever the cause, the end result is the same - you feel terrible. But the specific ways to improve this state depend on the underlying cause.

In many parts of the world, the idea that energy is closely related to health is not new. Traditional Eastern medicine, which originated thousands of years ago, is based on the concept that the flow of energy in the body determines health and vitality. Western medicine, on the other hand, has its roots in anatomy and physiology - objective entities that can be observed, measured, and dissected, and thus can be treated with drugs or surgery. Naturally, Western medicine has paid little attention to those "invisible forces".

Western medicine has achieved great success in extending human lifespan, increasing the average lifespan by 30 years in less than a century. However, its effectiveness in extending the healthspan (the number of years a person lives in good health) has been relatively limited. According to an estimate in 2021, globally, the average human lifespan exceeds the healthspan by 9 years.

Going with the flow of energy

Martin Picard of Columbia University believes it's time to change the focus of medical research. Instead of just concentrating on treating diseases, we should gain a deeper understanding of health itself. He argues that to do this, we must better understand how energy flows within the body. He says, "We've steered away from this direction because the reductionist science of the past has given us limited tools - if something can't be sequenced, seen under a microscope, or measured with an oscilloscope, then it's not considered a suitable object of study. I think this limitation has made us miss out on some things that could be very important and valuable."

Picard was trained in the laboratory led by geneticist Doug Wallace, a pioneer in mitochondrial research. Mitochondria are known as the cell's energy factories, responsible for converting digested food molecules into chemical energy that cells can use. Research quickly found that when mitochondria don't work efficiently, people often feel tired and lethargic. Based on this discovery, Picard expanded his research and created a new field - mitochondrial psychobiology - which specifically explores how the energy release of mitochondria affects our sense of energy and how our sense of energy, in turn, affects mitochondrial energy release. He and other researchers found that even in healthy people, mitochondrial dysfunction can be caused by a variety of reasons, some of which are almost certainly related to the prevalence of TATT.

Surprisingly, one of the biggest factors affecting mitochondrial energy production is an excess of fuel. The process of energy release by mitochondria occurs through a series of small biochemical steps. This process cannot be accelerated and must follow a specific sequence; otherwise, it will lead to metabolic pile - up. If too much fuel is consumed in a short period, mitochondria have to pause energy release and let cells store the excess energy for later use. As a result, energy actually decreases in the short term rather than increases. A high - sugar diet is especially problematic. Studies show that a high - sugar diet can lead to inefficient mitochondria, making people feel down and sluggish rather than energetic. Interestingly, some evidence suggests that a ketogenic diet, which is low in carbohydrates and high in fat and involves a significant reduction in sugar intake, may have the opposite effect on mitochondria.

In addition, both emotional stress and physical stress such as infection or injury can have a huge impact on the body's energy system. A study by Picard and his colleagues found that stress can increase the rate of cellular energy consumption by 60%. One important reason is that mitochondria not only produce energy but also produce cortisol - a stress hormone that signals to the body that it needs extra energy to deal with an upcoming challenge.

Stress not only directly consumes energy but also affects the body - brain's energy calculation mechanism. Lisa Feldman Barrett, a neuroscientist at Northwestern University, proposed the concept of "body budgeting" to describe the role of the brain in managing energy supply to ensure survival. She links body budgeting to predictive processing - a theory that suggests the brain works by generating "best guesses" about the external world and adjusting them based on the sensory information it receives. When the brain's predictions don't match the actual situation, this "error" signal is manifested in the form of emotions or feelings, whether it's pleasure or anxiety, energy or drowsiness. She explains, "We think these feelings are like an overall summary of the body's metabolic state."

This mechanism can explain why even if you had a good night's sleep the previous day, just thinking about a full - day meeting schedule can still make you feel tired. Similarly, it explains why a sudden piece of good news can make you instantly energized. The body's energy state hasn't changed, but the brain's prediction of the available energy has, thus changing our subjective feeling.

A study led by Arran Davis of the University of Oxford shows that this brain prediction mechanism has a real impact on our energy consumption. When subjects were asked to exercise to the limit, those accompanied by supportive friends could persevere longer and burn more calories before giving up. Davis explains that this indicates that when we know we have support and help, we're more willing to tap into our energy reserves. He points out, "Social support sends a signal to the brain that the resources needed for recovery are available, so we don't need to be as cautious when consuming the body's resources."

The factors affecting the body - brain's energy assessment are extremely complex, including both physiological and psychological ones, and many processes occur unconsciously, making objective measurement extremely challenging. However, scientists have identified several possible "biomarkers" that can reflect physiological processes and the subjective feelings of vitality or fatigue.

One key biomarker is growth differentiation factor 15 (GDF15), a metabolic signaling molecule that is released when cells are under stress. Whether it's infection, injury, or psychosocial stress, it can cause changes in GDF15 levels. Stephen O’Rahilly of the University of Cambridge says that GDF15 seems to be an "all - purpose" stress signal that warns the brain to conserve energy.

Another research direction suggests that GDF15 may explain why aging always makes people feel more tired. GDF15 is considered a reliable marker of aging, and its blood level rises by about 25% every decade. Picard believes this is closely related to energy budgeting. In a recent paper, he proposed that many symptoms of aging (including fatigue) may stem from the accumulation of cellular damage, which leads to an increase in repair costs while the energy supply struggles to keep up. When there's more and more "waste" inside cells, they send stress signals to the brain, and the brain's response is to conserve energy as much as possible.

Picard explains, "GDF15 is like saying, 'The metabolism is overloaded, cut costs!' So, muscles start to atrophy, vitality declines, and hair turns white - these are all ways to save energy."

Meanwhile, other researchers are exploring different biomarkers. In 2021, the World Health Organization (WHO) convened a group of experts on health and aging to try to formulate a brand - new definition of health, no longer based on "being disease - free" but on "vitality capacity" - that is, whether the body can effectively obtain enough energy from food to maintain normal functioning. Ivan Bautmans, a geriatrician at the Free University of Brussels, co - led this research team. They explored a variety of possible vitality assessment indicators, including muscle strength, inflammation markers in the blood, and even asking people to directly rate their own energy levels. One very promising method originated from Bautmans' doctoral research 20 years ago, which is to assess energy levels through a muscle endurance test.

This test is called Eforto. It measures the time it takes for a subject's grip strength to decline by 50% when squeezing a device with maximum force. The test results are combined with a questionnaire about the current energy level to calculate a composite score. Bautmans says that the final score can reflect the subject's physical and psychological energy levels. "It's an indirect measurement that can determine whether the physiological state is imbalanced or there's a problem." In a study involving nearly 1000 middle - aged people, those with the lowest scores were more likely to have biomarkers of low - grade chronic inflammation detected in their blood than those with higher scores. And this chronic inflammation is considered a key factor driving aging. This also raises an intriguing question: If we can detect problems early and take the right intervention measures, is it possible to slow down the aging process itself?

Taking control of energy

A study by Picard and his colleagues brings hope, suggesting that we may have a way to influence the aging process. He was interested in cases where people's hair turned white and then started growing in colored from the roots again. So, he recruited 14 volunteers who had experienced a similar phenomenon and conducted a study. The study found that the period when their hair turned white often coincided with a high - stress phase in their lives. And when the stress subsided, the hair color began to return.

Picard believes this is the result of the body - brain system re - allocating energy in the short term - the energy originally used for hair pigment production was prioritized for more important physiological needs. He explains, "When your stress eases, the energy budget may release a portion to be used for pigment production again."

Of course, this doesn't mean that white hair can be reversed at will. As we age, the changes in the body's functions will ultimately make white hair an inevitable result. But this discovery shows that the rate of aging may be more malleable than we thought.

Viewing fatigue as the result of the dialogue between the body and the brain also provides a new perspective for understanding chronic fatigue syndrome [CFS, also known as myalgic encephalomyelitis (ME)]. The symptoms of this disease have long been difficult to explain. If we can better understand the energy pathways involved, doctors can more precisely identify potential problem areas. For example, the latest research links chronic fatigue syndrome to the following factors: reduced blood flow, which leads to insufficient fuel supply for mitochondria; chronic inflammation, which continuously consumes the body's energy reserves; and a "processing bottleneck" in the brainstem - the brainstem is a key center for interoceptive processing and is responsible for managing the energy budget.

In our daily lives, this latest understanding of vitality also reveals new ways to deal with fatigue. One possible strategy is "deep rest", a concept proposed by Elissa Epel of the University of California. Epel studies the psychological benefits of contemplative practices such as meditation and prayer. She points out that these practices have been proven to contribute to well - being in part because they can calm the mind and body, thereby reducing the brain's over - protection of energy reserves.

Diet and exercise also play important roles in energy management. Studies show that high - sugar snacks can cause a rapid decline in mood and energy levels, a phenomenon closely related to low mitochondrial function. Short - term exercise ("exercise snacks"), on the other hand, can have the opposite effect. In addition, long - term regular exercise can force the body to increase energy output. It will remove inefficient old mitochondria and replace them with more efficient new ones, thereby enhancing the overall energy level.

Finally, it's worth noting that the people around you can have a significant impact on your energy level. So, no matter how busy your life is, even if you occasionally slack off in terms of diet and exercise, fortunately, our bodies and brains are naturally socially adaptable - as long as we're in the right social environment, we can usually find enough energy to support ourselves.