Olga Hernandez, 41, from Tucson, Arizona, has lost half her body weight—going from 405lbs to 13st 7lbs—after swapping fast food for home-cooked meals and undergoing a gastric sleeve surgery. Her incredible transformation helped her drop seven dress sizes, but left her with 17lbs of excess saggy skin. Olga, a mum-of-three and palliative nurse, had the…