A Few Things You Need to Know
the problems, necessary needs, and difficulties in space
First step to space: Space sick
Immediately after entering space, fluids in your legs and the lower part of your body move upwards towards your head. In fact, your face will feel and look swollen. Except for the occasional headache and congestion, astronauts usually aren’t bothered by this fluid shift. Some astronauts feel dizzy and have an upset stomach during the first few days of a space flight as they get used to zero gravity.
Daily Work Out
Your body is literally made for surviving here on earth. When you're in space, though, you don't normally use as many muscles and bones to get around, like walking or carrying things, due to its micro-gravity. Although it may seem like a luxury to you, it has a large toll/effect on your body. In bones for instance, this reduction leads to bone breakdown and a release of calcium, which is reabsorbed by the body, leaving the bone more brittle and weak. To prevent that astronauts exercise daily to maintain your muscle and bone health.
Eating in Space: The Challenge
Astronauts can't eat food the way we do here on earth. Since they don’t have a freezer, refrigerator, stove or microwave, most of the food has already been cooked, then freeze dried and vacuum packed (meaning the water and air has been taken out of it), or it is thermally stabilized (meaning treated and sealed in a package to prevent spoiling), much like camping food. These packages of freeze dried food can be reconstituted by adding water and then warmed up in a small warming oven. But they don’t want food that makes crumbs in space since crumbs would float all over the place and that could clog up equipment! Peanut butter, in fact, is the nearly perfect space food. It has no crumbs and almost everyone loves peanut butter!
I know what you're thinking: "How do astronauts eat on a space walk?" Let me tell you it's a completely different process. On a space walk they install a drink bag, a bag that holds water for the expedition. The bag has a drink tube with a valve which prevents free flow of water into the suit. The valve is opened when the crew sucks on the tube for water.