Having a light snack or a energy drink is really fine before starting up your workout. You need to have something before you workout in morning. Our body dosent gets anything whole night ,so it really needs proper nutrients in morning so as to start vigorous workout. Atleast having a fruit juice or any energy drink will help your body to regain the energy. And if you have a breakfast in morning before wotkout, you need to keep a healthy gap of 20 min between your workout and breakfast. Also keep on having 2-3 sips of water while workout so as to protect your body from dehydration.