I've heard so many times that you can't lose weight by doing tai chi or yoga. It actually made me give up my tai chi at one time. You CAN lose weight doing these sorts of exercises, they don't work on cardio as much but they are a form of strength training, both of which specifically target the core a very important area. It won't give you body building muscles but both tai chi and yoga should teach you to bear your own weight. You also burn calories, but everything you do burns calories

You can't lose weight doing tai chi or yoga alone, watching what you eat and being active throughout the day is important to. But I've been told so often that theres no point in doing tai chi or yoga because you can't lose weight - it's an activity and every activity you do can boost your weight loss - so if you enjoy it, do it! It's actually harder than a lot of people think. In my tai chi class people were dripping sweat after an hour.

 

AND you can gain weight! I did tai chi for a while years ago. When I started, I was quite, well, scrawny and unathletic. I was actually considered underweight for my age and height. But when I started Tai Chi I put on about 10lbs in the first few months....of muscle mass! Mainly on my quads and glutes......so don't let anyone tell you that tai chi isn't good for building muscle, either!