Stick to water to drink as calories consumed in beverage with no nutritional value are not worth it. I would then keep everything simple. eat something for breakfast-- hard boiled egg
, peanut butter on a bread thin, etc. These things stick with you and are not very high in calories. Then have a piece of fruit or low fat yogurt/skim yogurt for a snack (or whatever, carrots, apple, whatever you like) mid day.