Americans report high rates of chronic fatigue, but myalgic encephalomyelitis (ME), also called chronic fatigue syndrome (CFS), represents a distinct, clinically defined disease that affects a small subset of the population rather than a diagnosis that explains widespread tiredness. Around 2 million people currently have ME/CFS, which is characterized by crushing fatigue that does not improve with rest, plus post-exertional malaise, unrefreshing sleep, pain, and cognitive problems, such as brain fog.1

The exact cause of ME/CFS remains unknown. Research suggests that the condition can follow certain triggers, including acute viral infections and severe physical or psychological stress, but no single cause has been identified. In recent years, several studies have reported abnormalities in mitochondrial function and energy metabolism in people with ME/CFS, suggesting a possible role for disrupted ATP production.

Immune Cells Show Clear Signs of Energy Overload

A study published in Cell Reports Medicine examined how ME/CFS is linked to a failure in cellular energy production. For the analysis, the researchers looked at an array of biomarkers, including immune cell metabolism, immune cell composition, and blood makeup.2

The study population included 61 individuals who met strict diagnostic criteria for ME/CFS, meaning they had long-standing fatigue, profound crashes following physical or mental effort, unrefreshing sleep, and cognitive problems.

•There is an ATP imbalance — The study found that adenosine monophosphate (AMP) and adenosine diphosphate (ADP) — two forms of energy molecules that rise when the cell exhausts adenosine triphosphate (ATP) — were elevated in ME/CFS patients. To put that into perspective, ATP is your body's ideal energy format, whereas ADP and AMP are the substrates for ATP synthesis. If your body begins to use these, the energy you're using is substandard.

•A theory on how cellular energy production is compromised — The researchers believe that those with ME/CFS have trouble producing enough energy due to an obstacle in the production chain. While their findings aren't solid enough to propose a definite conclusion, here's what they theorized:3

"The elevated NAD+ [nicotinamide adenine dinucleotide] levels observed in PBMCs [peripheral blood mononuclear cells], together with the increased AMP and ADP, suggest that NAD+ is not being efficiently reduced to NADH [nicotinamide adenine dinucleotide + hydrogen] to drive ATP synthesis through oxidative phosphorylation.

This impaired reduction of NAD+ to NADH may also help explain the observed inverse correlation between plasma AMP and PBMC ATP levels, although this finding requires further study."

•Another major finding involved the natural killer (NK) cells — The researchers also discovered changes in the balance of immune cell types, including a reduction in certain mature dendritic cells and terminal NK cells. These normally help coordinate immune responses and act as a first line of defense.

When the population of NK cells drops, the immune system loses some of its agility and responsiveness. This means the fatigue you're feeling is not only about energy loss — your immune system shifts into a pattern that reflects reduced readiness.

•Blood tests paint a more complete picture — The team reported higher levels of proteins associated with thrombus formation and altered vascular reactivity in the ME/CFS group. For context, thrombus means blood clot formation, and vascular reactivity reflects how blood vessels respond to signals that regulate tightening and relaxation.

When these protein levels rise, it suggests the lining of the blood vessels is under strain, which disrupts healthy circulation. For someone with ME/CFS, that could mean poor oxygen delivery, dizziness upon standing, and cold extremities.

•The study highlighted where the largest metabolic imbalances appeared — Individuals with the most altered ATP-to-ADP ratios tended to show larger distortions in immune cell composition. That suggests a link between energy depletion and immune exhaustion. If the immune system lacks energy, its cells lose the ability to mature properly or carry out normal defense tasks.

In addition, the vascular protein shifts closely aligned with the energy imbalance. When cellular energy drops, blood vessel function suffers. When this happens, the delivery of nutrients and oxygen is affected. This creates a loop that leaves the entire body underpowered.

•The biological mechanisms behind these findings trace back to disrupted ATP production — Normally, mitochondria generate ATP through oxidative phosphorylation, a process that depends on oxygen, nutrients, and intact cellular machinery.

When ATP falls and ADP or AMP rises, the cell enters a state of metabolic stress. Here, the cell may shift into emergency survival mode instead of normal function. That shift drains resilience, reduces cellular performance, and leaves tissues — especially the immune system and blood vessels — operating at a deficit.

•Another mechanism involves immune maturation — Dendritic cells and NK cells rely on ATP to fuel activation, communication, and response signaling. When ATP drops, these cells lose their functional sharpness. The study found this exact pattern: fewer mature cells and more signs of immune imbalance.

•Mechanistic hallmarks of ME/CFS — Although the paper did not measure symptom improvement over time, it did compare variables to determine which markers best distinguished ME/CFS participants from healthy controls.

A statistical model that incorporated metabolic markers, immune shifts, and vascular proteins reliably separated the two groups. This includes an abundance of AMP and ADP. In addition, the immune system is skewed towards less mature pathogenic fighters, alongside a lower population of NK cells.

Energy Deficits Push the Immune System Toward Burnout

In a related study published in Biomolecules, researchers showed how energy metabolism and immune function interact in ways that worsen symptoms of ME/CFS over time. Here, they used a broad body of evidence to map out how energy shortages inside cells feed directly into immune dysfunction, especially immune senescence and immune exhaustion.4

•Mitochondrial dysfunction stands at the center of this illness — However, the study adds something new to the conversation. In particular, the researchers noted that those with ME/CFS have compromised levels of carnitine, which is needed for fatty acid oxidation and energy metabolism.

Moreover, the researchers noted that this chemical helps maintain integrity of the mitochondria and reduce the production of reactive oxygen species (ROS). The image below provides an overview of their hypothesis:

Source: Biomolecules. 2025 Mar 1;15(3):357

•The link to viruses — The paper identifies striking parallels between ME/CFS and chronic viral infections. In chronic viral states, the immune system fights for long periods without rest. Over time, some immune cells lose function and responsiveness through a process called cellular senescence, a state in which cells remain alive but no longer divide or respond effectively to threats. And when this reaches a chronic state, ME/CFS pathology occurs.

•Immune function breaks down — The immune system in people with ME/CFS shifts into a dysfunctional state. Similar to the previous study, they have altered NK cell function, changes in cytotoxic T cells, and persistent immune activation patterns that resemble those seen with unresolved infections.

•How energy metabolism and immune regulation are linked — The researchers argue that mitochondrial defects impair the immune system's internal communication network. In addition, the same dysfunction creates a bottleneck for immune activity itself. In other words, your cells do not produce enough energy to meet the demands of immune signaling, repair, or defense.

•ME/CFS displays patterns of metabolic inflexibility — Cells struggle to switch between energy pathways or ramp up ATP production during stress. When your cells cannot adapt, even minor activity can produce a disproportionate crash. The featured study highlights published literature showing impaired energy production and utilization.

•Immune exhaustion driven by chronic metabolic strain — The paper explains that persistent energy deficits interfere with immune cell communication and their ability to generate powerful responses. When immune cells lack ATP, they lose the ability to proliferate, secrete cytokines, or kill infected targets effectively.

Strategies to Reclaim Your Energy and Live Life to the Fullest

If you're low on energy, the solution isn't drinking more coffee or energy drinks. It lies in your mitochondria, which has been compromised to such a point that it can't function properly anymore. That said, I'll be releasing a new book soon, "Cancer Cure," which explores what changes occurred in our society today that resulted in a dramatic rise in metabolic dysfunction among millions of Americans.

The book will also discuss several strategies that can help you regain your cellular energy and improve your quality of life. Here are some of my recommendations:

1.Reduce linoleic acid (LA) intake — One of the reasons why you're feeling fatigued is excess intake of LA, one of the most prominent toxins in the Western food supply. In fact, I'd go so far as to rank it above refined sugar, although that plays a role, too.

The reason why I'm saying this is because excess LA generates reactive byproducts that eventually suppress immune behavior, as well as damaging your mitochondria. So, get rid of any foods you have that contain LA, which are mainly seed oils — soybean, corn, cottonseed, canola, sunflower, and grapeseed.

In a previous article, I mentioned that modern Western diets now contain 15 to 25 grams of LA daily, which is a far cry from the estimated 2 to 4 grams that pre-industrial populations consumed.

In light of this, I recommend you keep your LA intake below 5 grams a day; if you can keep it below 2 grams, that's even better. To track the LA in your food, sign up for the upcoming Mercola Health Coach app. It contains a feature called the Seed Oil Sleuth, which calculates daily LA consumption to a tenth of a gram. Swap LA-rich seed oils for healthier saturated fats like grass fed butter, ghee, tallow, and coconut oil.

2.Familiarize yourself about sources of LA — You'll find LA not just in cooking oil sold in grocery stores. They're found in most ultraprocessed foods, so it's important to read through the ingredient list of whatever you're buying.

In addition, it would be wise to minimize the times you eat in restaurants or order takeout. Unless strictly stated otherwise, it's safe to assume that all the food cooked in these establishments use seed oils.

LA also is found in conventionally raised chicken and pork due to the ultraprocessed nature of their feed. Prioritize beef, lamb, bison, and other ruminants, which are likely to have lower LA levels.

3.Support your immune cells at the mitochondrial level — When ATP runs low, immune cells can't communicate, divide, or kill threats efficiently. Several natural compounds have shown promising effects in boosting mitochondrial resilience and NK cell performance:

•Beta-glucans from yeast and mushrooms wake up your immune system by activating macrophages and NK cells.

•PQQ, found in papaya and green tea, sparks the production of new mitochondria and protects them from oxidative wear and tear.

•Urolithin A, a gut-derived compound from pomegranates, recycles defective mitochondria to keep your cellular engines running clean.

•Polyphenols like quercetin, fisetin, curcumin, and resveratrol scavenge harmful free radicals and reduce inflammatory suppression of NK cells.

In preclinical studies, when NK cells were given a combination of these compounds — delivered via nanoliposomes that targeted mitochondria directly—their killing capacity jumped five to tenfold. Instead of exhausting after five to ten kills, these cells could eliminate 30 to 50 targets before tiring out.

4.Repair your gut — Aside from your mitochondria, LA also wrecks your gut microbiome, which plays an extensive role in your health, including energy metabolism.5

Gut repair requires adequate carbohydrate intake to support intestinal cells and microbial balance. Your gut lining relies on glucose as a primary fuel, and insufficient carbohydrate intake can slow repair and weaken barrier integrity. Most adults need at least 250 grams of carbohydrates per day, adjusted for activity level and metabolic status. This intake supports gut repair, thyroid signaling, and overall energy balance.

Begin with well-tolerated carbohydrate sources such as sweet potatoes, carrots, winter squash, ripe fruit, and cooked white rice. These foods supply glucose while being lower in fermentable substrates. Add high-fiber foods slowly if gut health remains poor. Large amounts of fiber can intensify bloating, cramping, and constipation when intestinal permeability or dysbiosis persists. In this phase, prioritize digestible carbohydrates first and increase fiber only in small, gradual steps as tolerance improves.

As epithelial integrity strengthens and immune signaling stabilizes, fiber tolerance will improve as well. At that point, a broader range of fiber-rich foods can support short-chain fatty acid production and long-term resilience.

5.Exercise with restraint and precision — Your immune system relies on cytotoxic T lymphocytes and NK cells to remove damaged or dysfunctional cells. In ME/CFS, immune signaling, mitochondrial output, and energy recovery all falter, which changes how your body responds to physical stress. So, conventional exercise advice does not apply here.

High-intensity or endurance exercise often worsens symptoms and can trigger post-exertional malaise, a hallmark feature of ME/CFS. Rather than restoring immune function, excessive exertion can deepen mitochondrial injury and prolong recovery.

The goal is not fitness training. The goal is cellular signaling without metabolic overload. Most ME/CFS researchers emphasize gentle, low-stress movement that respects your available energy. Appropriate options include slow walking, light stretching, yoga, tai chi, and short bouts of resistance exercise that use body weight or very light loads.

Time and intensity matter more than duration. Many patients tolerate exercise best in intervals lasting seconds to a few minutes, followed by full recovery. Heart-rate monitoring and pacing strategies help you stay below your anaerobic threshold, which lowers the risk of symptom relapse. As mitochondrial function and autonomic balance improve, capacity often expands gradually.

Progress depends on consistency, recovery, and restraint, not intensity. Any program should adapt to daily energy limits rather than fixed schedules or goals.

6.Get restorative sleep — This is another cornerstone of health that's often overlooked. In the case of people diagnosed with ME/CFS, research shows that sleep habits are often compromised — longer sleep onset latency and reduced sleep efficiency are common occurrences.6

When you get proper sleep, your body undergoes crucial repair processes. In particular, sleep allows your immune system to rest, allowing optimal surveillance in the long run against wayward cells that contribute to fatigue.

If you're having a hard time sleeping, there are many strategies to help you. Read "Sleep — Why You Need It and 50 Ways to Improve It." There, I also go over the science on what happens to your body while you rest, as well as the consequences of insufficient sleep.