7 Legit Medical Reasons You Feel Exhausted

Why Do I Feel Like CRAP?! Doctor Exhausted Man Repeller-Feature

If staying in is the new going out, then why are so many of my patients telling me they are flat-out exhausted? Every day I hear this complaint from 20, 30 and 40 year olds in the prime of their lives.

Their body aches. They can hardly keep their eyes open at their desks. They can’t concentrate. They’re almost sheepish when they admit it, because who wants to admit to their doctor that they are sleepy, much less ask for help for it?

The truth is that most of these patients are exhausted by life — by an endlessly stressful news cycle, next-level career ambitions and an addiction to screens — and that exhaustion can lead to more severe chronic diseases if left untreated.

Here are the seven of the most common reasons you may be feeling exhausted and spent. If any of this sounds familiar, then you should probably see a doctor and get tested. It’s not normal or pleasant to be permanently wiped out.


You could have an iron deficiency.
If you get your period regularly and don’t eat enough meat or take an iron supplement, you could be anemic, meaning you have too few red blood cells to carry oxygen around your body — making simple tasks like climbing a flight of stairs seems unreasonably hard. A simple blood test from your doctor can rule this out!

You’re out of shape.
We live ridiculously sedentary lifestyles. The average person spends 11+ hours a day in front of a screen. Tech was supposed to give us more freedom, but instead it’s the new ball and chain. If you sit all day and only spend a few minutes a few times each week working out, you may be what’s known as “deconditioned,” meaning your muscles fatigue easily.

You’re too in shape.
Overdoing what I call “long-haul cardio” (running and spinning in particular, but really all forms of overexercise), leaves people depleted, dehydrated and deflated. If you find yourself relying on coffee and sugar-bomb fruit smoothies to keep your energy up and are working out hard six days a week, you could be sapping your reserves. This contributes to adrenal fatigue, which results from spending too much time in “fight or flight” mode where cortisol and adrenaline are high. Your body never has a chance to recover.

You’re getting low-quality sleep.
Maybe you’re in bed for seven hours, but thanks to the blue light emanating from your laptop and those 30 minutes spent scrolling Insta when you get into bed, your circadian rhythm is disrupted, your cortisol is high at when it should be low and you’re tossing and turning, not hitting the ideal three or four full REM cycles per night that we need to feel rested.

It could be your thyroid.
What is that? It’s a gland in your neck that drives your metabolic rate and governs things like digestion, weight, energy and mood. One in eight women in the U.S. will be diagnosed with a thyroid problem in her lifetime and many are undiagnosed. At Parsley Health, the most common reasons we see thyroid dysfunction are nutrient deficiencies, gluten sensitivity and inflammation resulting from a high-carb/high-sugar diet. Autoimmune conditions are also a major reason; doctors often don’t test for the antibodies to find it. We test all patients’ thyroids routinely because it is such a common problem.


It could be depression.
“I’m tired” has become polite code for “I’m in a bad mood.” If you feel irritable, anxious and down most of the time, you could be suffering from low-grade depression — known in doctor-speak as “dysthymia.” You may feel this way because your body is inflamed from eating too much sugar and processed food, because you’re low on key nutrients like B vitamins and magnesium or because you’re chronically not getting enough sleep. When you address these issues, the symptoms of depression and anxiety often get significantly better or disappear.

You may have a vitamin D deficiency.
Over 80% of our patients at Parsley Health are vitamin D deficient because most don’t spend enough time in the sun — even in California! Vitamin D is a hormone, not just a vitamin. It’s available in fatty foods like cod-liver oil, and your body makes it when you are exposed to sunlight. Vitamin D is crucial for bone health and calcium absorption, but also regulates the immune system. If you’re getting too many colds and sinus infections, leaving you feeling run-down, start boosting your intake of vitamin D. We recommend supplementing 5000IU with vitamin D3/K2 drops if you know you are low, and 2000IU for anyone even if you haven’t been tested.

Graphic and illustrations by Maria Jia Ling Pitt.

Robin Berzin

Robin Berzin is the founder of Parsley Health, which combines nutrition prevention and wellness with cutting-edge medicine and testing from top doctors who help you live a healthier life. To learn more, visit You can also schedule a free consult call by visiting

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