Stress according to Yoga is imbalance.
During stress our body reacts by
- pouring the stored sugar and fats into the blood-stream to provide fuel for quick energy,
-flooding the red blood cells into the blood-stream to carry more oxygen to the muscles of the limbs and the brain,
-speeding up the heart and soaring blood pressure ensuring sufficient blood supply to needed areas,
-ceasing digestion ,so that blood may be diverted to the muscles and the brain,
-loosening of bowel and bladder muscles etc.
Hence long duration of stress leads to Atherosclerosis,Diabetes,Hyperacidity,Colitis,
Migraine,Tension Headache,Hypertension etc.
Hence one should be very careful about diet during this stressful life and try to revert this imbalance by pranayam,yoga,aerobic exercises,involvement in creative art, etc.