A restricted-calorie diet was shown to inhibit the development of precancerous growths in a two-step model of epithelial skin cancer. In contrast, an obesity-inducing diet activated skin cancer pathways.
Epithelial cancers, which comprise 80 percent of all cancers, are those which arise in the tissue that lines the surfaces and cavities of the body's organs, in this case the skin.
Calorie restriction and obesity both directly affected activation of the cell surface receptors epidermal growth factor (EGFR) and insulin-like growth factor (IGF-1R). Calorie restriction inhibits their signaling, and obesity enhances it, leading to cell growth and proliferation.