I need a lot of data to make my application really work. Statistics without the underlying data would help some, but I really want to be able to do my own modeling/analysis on a data set.
I've been searching the web without luck. Does anyone know of any resources for acquiring valid data sets that can be used commercially? In my case specifically, I'm looking for data related to human health, exercise and weight loss.
Most datasets on the web are going to be latitudinal surveys of a population in time, though they may span several years. It sounds like you might want a specific kind of longitudinal study following individuals over time and tracking their individual weight changes and relating that to their personal exercise routines. As garish as it is, http://www.bettycjung.net/Phdata.htm actually has a wide variety of health data links and is probably your best bet.
Finally, a few more links from my bookmarks which look like they might help you (though I haven't looked through them to be sure): http://www.who.int/whosis/en/, http://www.lib.berkeley.edu/PUBL/stats.html, and http://phpartners.org/health_stats.html. Good luck!