To learn more about what's happening on the International Space Station at any given time, check out NASA's frequently-updated ISS blog or their page about the research and development work happening on ISS.
Depends on your body type and metabolism and your routine. But usually it takes around 3 to 4 weeks for visible results. For me it took me a couple of months to actually see any progress visually.
See More: you asked, weight gain, exercise, It's true that many people either gain a little weight or don't see any change on the scale for as long as 4-6 weeks after making a significant change in their level of exercise.