Jessica Alba Started Dieting At Age Of 12, Dark Angel star Jessica Alba has been on a diet since the age of 12. it's taken years of self-control to get her body in trim. Alba says, "Everyone in my family is overweight. I wanted to be healthier, so I started cooking for myself when I was 12." And Alba has even dropped a few hints for anyone wanting to follow her example. She adds, "I don't eat desserts or red meat. I stick to egg-white omelets, poultry, fish, vegetables, salads and fruit."