Stress is on of the biggest precursors of acne, especially beyond puberty. Controlling stress can reduce the release of the stress hormone cortisol, and therefore reduce the severity of the acne.
Eating refined carbohydrates (white bread, pasta, rice, flour etc) and sugar leads to a surge in insulin and an insulin-like growth factor called IGF-1. This in turn leads to an excess of male hormones, which encourage the skin to excrete large amounts of sebum. This grease-like substance encourages the growth of bacteria responsible for acne.
