They are packed in food lockers. Some of the snacks include nuts and cookies. Sometimes the astronauts take their favorite snacks. The same kinds as on earth - protein, calories, vitamins and minerals. We are working on understanding some of the mechanisms of muscle and bone loss.
Exercise is also a very important component as is food.
What is the rda for astronauts in space. Many of the reommendations depend on the nutrient. Choices include eggs dishes and cerals, there are several breads flown. Typically 40-45 hours a week.