. >> reporter: kelaf sharp always thought he was in pretty good shape. he is a personal trainer and realtor in birmingham, alabama. but type 2 diabetes runs in his family. >> my grandmother had diabetes my mom my sister has it >> reporter: kelaf was so busy, he used to grab fast food, sweet tea, energy drinks. >> people see you and think, oh, you work out. you're healthy there's nothing wrong with you that's not the case. >> not if you're not eating right. >> exactly >> reporter: a few years ago he was diagnosed with type 2 diabetes and prescribed medicine. but kelaf wanted alternatives so he volunteered for a study at university of alabama at birmingham, looking at two diets. kelaf was put on a low carb diet for three months every tuesday, a box of food arrived with recipes. >> eggs with vegetables you can put whatever vegetables you want in it >> no carbs? >> no carbs. >> reporter: this nutrition researcher launched the study five years ago. >> americans tend to eat a lot of sugar and carbohydrates and you reach a limit to the ability to store the exce