Written by Cesare Attuoni
16th Mar 2022 • 3 minute read

While changes in your energy levels are normal, long periods of tiredness might be a sign that something else is going on. A lot of factors can affect your energy — from hormones and diet to lifestyle choices. Understanding what’s causing you to feel tired is the first step to tackle possible fatigue. Here are the main reasons your energy levels might dip. 

How hormones affect your energy

Your hormones are chemicals that play a key role in controlling your body’s processes — for example, your body temperature and heart rate. An imbalance of hormones in your body can result in a variety of symptoms, including tiredness and difficulty sleeping. 

Certain hormones, like oestrogen and progesterone, can hugely affect women’s energy levels. Other hormones, affect the energy levels of both men and women. 


Testosterone is often called a “male” hormone. But it’s also really important for female health —  females just produce it in much lower amounts. Low levels of testosterone, in both males and females, can cause extreme tiredness and fatigue. 

Your testosterone levels naturally drop with age. But there are many things you can do to help maintain a healthy level of testosterone in your body — like eating a varied diet and not drinking excessive amounts of alcohol. 

How does cortisol affect your energy?

Cortisol is a hormone that helps your body respond to stress. While cortisol is essential for your health, it becomes an issue when your levels are raised all the time (due to chronic stress). High cortisol levels can cause tiredness, difficulty sleeping, and irritability.

If you want to understand the impact stress could be having on your body, you can measure your cortisol levels with a blood, urine, or saliva test.

How do thyroid hormones affect your energy levels?

Your energy levels are affected by hormones produced by your thyroid gland. These hormones help control your metabolism — the chemical processes that occur in your body that keep you alive, like breathing and breaking down food into energy. 

If your thyroid is underactive, your bodily processes start to “slow down” and you might feel tired, have memory problems, and feel depressed. While if your thyroid is overactive, you might feel restless, anxious, and have trouble switching off causing sleep problems.

You can check your thyroid function with a blood test.

How diet affects your energy

Eating a balanced diet is very important for overall health. But there are a number of nutrients that are key to maintaining good energy levels. These include:

  • iron — low iron levels can lead to iron-deficiency anaemia, causing tiredness and shortness of breath.
  • vitamin D — symptoms of vitamin D deficiency include tiredness and weak muscles.
  • vitamin B12 and B9 (folate) — a deficiency in either vitamin can cause tiredness and weakness. 

In addition to eating a nutritious diet, it’s recommended to eat at regular intervals to keep your energy levels consistent — for example, consuming at least three meals a day.

Blueberries in white bowl

How water affects your energy

Dehydration can affect your energy, as well as your brain function and mood. You should aim to drink around 6-8 glasses of water a day.

How sleep affects your energy

Sleep is what allows your body to recover and recharge, ready for the next day. A good sleep routine and getting around 7-9 hours of sleep a night, so you wake up feeling refreshed, can greatly improve how you feel when you’re awake. 

How exercise affects your energy

It might feel counterintuitive, but exercise can be an antidote to feeling tired. When you exercise, your body releases endorphins — hormones that make you feel energised and positive. Even just a 10-minute walk has been found to help shake off the feeling of low energy.