
Tiredness is the symptom most often treated with supplements and least often investigated. The order here is deliberate: the blood test comes first, because if you are iron deficient or hypothyroid, no amount of diet change will touch it.
Before anything else, see a doctor for a blood test if your tiredness has lasted more than a few weeks, and especially if you are also breathless, unusually pale, losing weight without trying, bruising easily, or having very heavy periods. Iron deficiency, thyroid disease, coeliac disease, diabetes and depression all present exactly like this and all need diagnosis, not diet.
The week-by-week plan, the foods, the supplements worth taking and the ones to skip. The safety section above stays free, always.