Causes of Fatigue and lack of energy

By: Nutrition expert- Vidula Kozarekar, Mumbai.

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Fatigue is a common non-specific symptom experienced by many people and is associated with many health conditions. Often defined as an overwhelming sense of tiredness, lack of energy and feeling of exhaustion, fatigue relates to a difficulty in performing voluntary tasks. Fatigue accumulation, if not resolved, leads to overwork, chronic fatigue syndrome (CFS), overtraining syndrome, and even endocrine disorders, immunity dysfunction, organic diseases and a threat to human health (1).

Acute fatigue & chronic fatigue:

There are many different fatigue classification methods. According to its duration, fatigue can be classified into acute fatigue and chronic fatigue. Acute fatigue can be quickly relieved by rest or life-style changes, whereas chronic fatigue is a condition defined as a persistent tiredness lasting >months that is not ameliorated by rest (2), (3).

Fatigue can also be classified as mental fatigue, which refers to the cognitive or perceptual aspects of fatigue, and physical fatigue, which refers to the performance of the motor system (1).

Muscle fatigue:

Muscle fatigue is defined as a decrease in maximal force or power production in response to contractile activity. Muscle fatigue is a commonly experienced phenomenon that limits athletic performance and other strenuous or prolonged activity. It also increases and restricts daily life under various pathological conditions, including neurological, muscular and cardiovascular disorders, as well as aging and frailty (4).

Mental fatigue:

Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity and characterized by subjective feelings of “tiredness” and “lack of energy” (5). mental fatigue is a common symptom in a large number of chronic medical conditions such as cancer, Human Immunodeficiency Virus, Multiple Sclerosis, Chronic Fatigue Syndrome, Alzheimer’s disease, Huntington’s disease and Parkinson’s disease (6).

What causes fatigue?

Lifestyle factors:

  • physical exertion
  • lack of physical activity
  • lack of sleep
  • being overweight or obese
  • periods of emotional stress
  • boredom
  • grief
  • taking certain medications, such as antidepressants or sedatives
  • using alcohol on a regular basis
  • using illicit drugs, such as cocaine
  • consuming too much caffeine
  • not eating a nutritious diet

Medical conditions:

  • Anaemia
  • Sleep apnoea
  • Underactive thyroid
  • Celiac disease
  • Chronic fatigue syndrome
  • Diabetes
  • Depression
  • Anxiety

Lifestyle changes that can help reduce fatigue:

  • drink enough fluids to stay hydrated
  • practice healthy eating habits
  • exercise on a regular basis
  • get enough sleep
  • avoid known stressors
  • avoid a work that’s overly demanding
  • take part in relaxing activities, such as yoga
  • abstain from alcohol, tobacco, and other illicit drugs

When to see a doctor?

If you’ve made efforts to address the most common lifestyle causes, such as lack of rest, poor eating habits, and stress, without success, and your fatigue has continued for two weeks or more, make an appointment with your doctor.



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