Looking at your blood counts can reveal many nutritional and metabolic diseases. Vitamin deficiency’s such as Iron, Vitamin B12, and Folic Acid can cause your blood to be anemic (low red blood cell counts). A slow thyroid can also cause anemia since the body will also produce blood slow. Most obese people experience some level of fatigue and shortness of breath.  It is important to ensure these are not symptoms of anemia. Your white blood cell count (cells that fight infection) can also be affected by poor nutrition.