Thank You. My 20 Y.o. Nephew Felt Congested And Fatigued

Thank you. My 20 y.o. Nephew felt congested and fatigued all day. No hx. Of any medical conditions. He is not prescribed any message/TX. He ate a large bowl of pasta/ziti, clamp chowder, two glasses of iced Tea and a few entree pieces. Then stood up and lost consciousness. Ems came, sugar level, blood pressure and his awareness/responses were normal. Could his blackout be from a carbohydrate overload?