If you’re constantly asking yourself “Why am I so tired?”, you’re not alone. Fatigue is one of the most common complaints in both clinical practice and daily life. Yet, the underlying causes are often overlooked or misunderstood. Feeling low in energy isn’t just about being busy or stressed – it often reflects deeper imbalances in the body that need attention.

1. Lack of Sleep & Circadian Rhythm Disruption

Quality sleep is non-negotiable when it comes to energy. Inadequate sleep or disrupted sleep cycles (often due to screens, stress or irregular sleep routines) impair the body’s ability to restore, repair and regulate hormones like cortisol and melatonin. If your sleep is erratic or insufficient, this could be your number one cause of fatigue.

2. Low Nutrient Status

Nutrients are the raw materials your body needs to produce energy. Deficiencies in essential amino acids from protein, B12, folate, iron, and vitamin D can leave you feeling exhausted. These nutrients are key for red blood cell production, oxygen transport, and cellular metabolism. Whether due to a diet lacking in variety or poor absorption (more on that below), low levels can significantly impact your energy levels.

3. Gut Health & Absorption

Even the best diet won’t help if you’re not absorbing your nutrients properly. Poor gut health – think bloating, IBS symptoms, or frequent illness – can compromise your ability to absorb key vitamins and minerals. An imbalanced gut microbiome can also lead to low-grade inflammation, further draining your energy.

4. Blood Sugar Imbalance & Insulin Resistance

Energy crashes after meals, constant cravings, and that 3pm slump can all point to blood sugar dysregulation. If your body struggles to maintain stable glucose levels, it can result in both physical and mental fatigue. Over time, this can progress into insulin resistance, which is associated with low energy and increased inflammation.

5. Low Thyroid Function

Your thyroid is your metabolic thermostat. If it’s underactive, every system in your body slows down, including energy production. Common signs include fatigue, weight gain, constipation, dry skin, and feeling cold. Thyroid function can be checked via a full thyroid panel, including TSH, free T4, free T3, and thyroid antibodies. A TSH over 2.5 may be a sign the thyroid isn’t functioning efficiently.

6. Inadequate Calories & Over-Fasting

While fasting can be beneficial, overdoing it or consistently under-eating can backfire. Your body needs fuel to function, and under-eating (especially combined with high stress or lots of exercise) can leave you depleted and tired. Women particularly, tend to do better in a fed, rather than fasted state. We need adequate calories for proper thyroid, hormone and adrenal function.

7. Mitochondrial & Detox Function

Mitochondria are your energy factories. When they’re sluggish – due to oxidative stress, poor sleep, chronic stress, or low nutrient availability – your energy suffers. Detox pathways also play a role. If your liver is overburdened (due to alcohol, processed food, toxins, or hormonal imbalances), it can create a sluggish, foggy feeling.

How to Get to the Root

Consider running blood tests to assess B12, folate, iron (including ferritin), vitamin D, thyroid function, fasting insulin, and glucose levels. Your GP can run these tests, or you can have them done privately with a functional medicine practitioner or nutritional therapist, who can also assess your gut health and mitochondrial function.

What You Can Do

• Prioritise sleep with a regular routine and screen-free wind-down time. Avoid all sources of blue light after sundown (from your phone, TV and overhead lights). Look for orange-light lamps such as salt lamps and get a blue light filter for your phone, or invest in some blue light-blocking glasses.
• Eat a nutrient-dense, protein-rich diet, making quality protein the centre of your meals, and including a diversity of vegetables
• Balance blood sugar by avoiding ultra-processed foods and including protein and fibre in every meal. Eat a good-sized meal so you don’t feel the need to snack, grazing all day isn’t the ideal approach for your microbiome or your mitochondria
• Support gut health with probiotics, fermented foods, and identifying food sensitivities
• Move daily, manage stress, and spend time in natural light as much as possible to support your circadian rhythm and mitochondrial health. Prioritise exercise when you have the energy

Low energy is your body whispering for help. The good news? Once you identify and address the root causes, your vitality can return. Need help with this? Contact me for a free chat to see where I can help.