I think it would surprise many people to know that a big part of my motivation to move away from North America was weight loss. But crazily enough, it was! Where I lived prior to my move my lifestyle was horribly unhealthy - terrible food was cheap and easily accessible, I had to drive a car virtually everywhere (work, church, the store, most of my friends' places), and my job was hard and long enough that it was extremely difficult to be motivated to wake up early or stay up after I'd had [a late] dinner to exercise. When I did have free time I spent it with my friends, and when we were together we didn't do much beyond talking or watching TV. (Not their fault - I was tired enough most of the time that that was all I was up for!)
By the time I moved I'd been trying for years to lose weight and it just wasn't happening, in large part because the deck was stacked against me being able to do so. So while money was definitely the prime motivator in my move around the world, a change in lifestyle was a close second. I was tired of sitting in a car for hours a day. I was tired of sitting around. And as much as I love lattes and Sausage Egg McMuffins, I was tired of easily available fast food. I desperately needed a change, and it wasn't happening where I lived.
I should probably through a disclaimer in here: You can gain weight in China! I have friends who have, and indeed I have myself. If you go everywhere by taxi, spend the extra money to pickup a lot of Starbucks, KFC, and McDonald's, and never cook at home you can and likely will gain weight here. The second half of my first year here I embraced exactly this lifestyle and regained half the weight I'd lost my first six months here.
If, however, you embrace the perks of living here China makes it very easy to consistently lose weight. For starters, you can make the bus or metro your primary mode of transportation - you'll save a lot of money and suddenly have a decent amount of walking and standing (or gymnastics, depending on your bus driver!) built into your day. Take advantage of how ridiculously cheap many local grocery items (grains, vegetables, eggs, tofu...) are and cook at home whenever you have the chance - you'll save money and be eating healthier than you would be picking up fast food. (Trust me, there's no way you'll be putting more oil in your stir fry than the street food vendor or restaurant near your apartment!)
I grew up with some of these perks and they played a big part in my decision to change countries. Sadly enough, very few places in North America are designed for pedestrians anymore. Even Portland, Oregon - the one place I've lived in North America where I consistently lost weight - isn't always that pedestrian-friendly. China still is, however. (For the moment at least.) You may have to spend a little more time going from A to B, but the change will be worth it! I lost 18 kilos (40 pounds) my first 6 months here, thanks to the lifestyle changes mentioned above. Sure, it takes me 25 minutes to get to work instead of 10 or 15. But I walk a bit and I get to read in that time. The changes are small and easy, and I'm grateful to China - despite all its air pollution and environmental issues - for making some healthy life change achievable!
