Certain foods help you relax or cause stress in the body.
The normal American diet is fast food: the drive thru, microwaved or a quick pizza. These foods contain oils, sugars etc. and sometimes no minerals and vitamins essential for health. Digesting these foods sends a nerve response to the brain to release stress hormones (cortisol, catecholamines).
A consistent diet in these foods keeps our body in a stressed state. The side effects can be muscle/joint pain, tiredness, weight gain, etc. When this becomes our norm long-term diabetes, high blood pressure and increased chance for stroke/heart attack becomes real.