Microwave exposure has been known to induce mitochondria dysfunction. The mitochondria are the powerhouse of the cell. Dysfunctional mitochondria will interfere with the cells' ability to produce energy and can be linked to fatigue and possibly even obesity.
Exposure to long-term microwave radiation has been shown to change a particular form of white blood cell (lymphocyte) ratio - known as the T-helper/T-suppressor (T4/T8) cell ratio - from normal to abnormal. Abnormalities in this T-lymphocyte ratio have been shown to lead to an increased susceptibility to viral, fungal, and bacterial infections. Symptoms include sore throats, low-grade fevers, weakness, persistent fatigue, and swollen lymph glands.
Microwave exposure has been shown in studies to induce what is known as "subliminal" stress ( since the body does not know it is being stressed) causing the adrenal glands to excrete an abnormally greater amount of cortisol and adrenaline. Excretion of adrenaline, for one, can lead to irritability and a feeling of hyperactivity - the latter now very common in children with Attention Deficit Hyperactivity Disorder (ADHD). In a continuous state this will eventually lead to adrenal exhaustion, in which the adrenal glands just stop working.
Electromagnetic fields- like those emitted by cell phones - have been shown to alter regional cerebral blood flow. In conditions like autism and chronic fatigue syndrome (CFS) it has been shown via SPECT (Single Proton Emission Computed Tomography) scans that there is a decreased flow of blood to the brain.
From: http://www.naturalmatters.net/article.asp?article=2965&cat=247