Identifying Your Allergy
Of course understanding this won't in itself solve the problem – you need to know what the allergy is in order to restrict your intake of that food and address the problem. You also need to find out if it is in fact an allergy that is causing the problem.
To do this you can get a blood test that will test for various allergies. You can get this from your doctor or you can get a specific allergy test from a specialist. Alternatively to start getting an idea yourself you can try keeping a food diary and an energy diary. Every day you write into the diary what you have been eating and what your energy levels have been like and then look for correlations to identify problem foods. Likewise if it's not a food allergy causing the tiredness then you can make a note of other behaviors – such as the amount of pollen exposure or dander exposure. Bear in mind that allergies can sometimes take a while to kick in – so don't expect an immediate response. For instance cutting bread out of your diet won't immediately reduce tiredness you'll need to do so for a short while to start seeing the benefits