Is this why you feel tired all the time?

If fatigue has become a fact of life and your usual workout routine is becoming seriously hard work, you could be one of millions of people who are not getting enough iron.

Iron is essential for energy because it's a building block for the red blood cells that transport oxygen around the body — which explains why constant tiredness is a tell-tale sign that you aren't getting enough.

Looking pale and interesting is another sign of iron deficiency, along with feeling short of breath and being aware of your heart beating.

But there are many more ways your body could be warning you that you're low in iron.

Other tell-tale clues are headaches, dizziness, tinnitus — hearing sounds which seem to come from within your body, hair loss, cold hands or feet, difficulty swallowing, feeling itchy, disturbed sleep, lack of appetite, abdominal pain, having a sore or unusually smooth tongue, or brittle or spoon-shaped nails.

The study reveals that one in three female athletes have such low iron stores they are at high risk of clinical anaemia and three out of five — 60 per cent — are 'depleted' in iron, which is the first stage in developing a deficiency.

Dietitian Dr Carrie Ruxton, lead author of the paper, said; 'While the studies to date have focused on elite athletes, our research suggests that a chronic lack of iron is undermining the performance and potential of thousands of everyday exercise enthusiasts.'

A key goal for all elite sports stars and amateur athletes is to increase their VO2max score — the gold-standard measure of cardiorespiratory endurance and aerobic fitness.

But this can't be achieved without optimal iron levels.

Lack of iron limits oxygen transport around the body and takes the edge off your mental and physical performance.

Zanna Van Dijk, a personal trainer and fitness guru with a celebrity client list, said: 'When exercising, it is crucial that your body is well nourished so it can perform safely at its maximum ability.

'A lot of people ask me what they should be eating, and I always advocate that lean red meat should be included in their diet. 

'It provides a useful source of nutrients, such as iron, which is needed for energy — and gym bunnies and fitness fans need lots of it.' 

Red meat is one of our richest and most useful sources of iron, a steak will provide three times more iron than chicken and 250 per cent more than broccoli. 

The haem iron in red meat is also more readily absorbed than the non-haem form in plant sources.

Rin Cobb, co-author and clinical and sports performance dietitian adds: 'What's really shocking about this new research is that it shows how a supposedly very health-conscious group is actually undermining their performance and general health.'

Dr Ruxton agrees: 'Iron is essential for energy, so it is very difficult to achieve your peak performance without optimal levels. 

'One of the easiest ways to beef-up your stamina is to increase your intake of red meat towards the recommended level of 70g a day. 

'At present, women on average eat just 56g of red meat daily.' 

(dailymail.co.uk)