One of the, if not THE, most prominent teachers of Tai-chi is Yang-style grandmaster Yang ChengFu (楊澄甫). His famous “Ten essentials of tai-chi” has become the definitive guide to serious tai-chi practitioners. I have translated and commented on these important teachings in my previous posts. But…he looked quite over-weight.
First question: Is Yang’s overweight caused by his practice of tai-chi? The answer is a definite no. A counter example is Master Wu TuNan 吳圖南 who was slim and healthy and lived up to 100 plus. But both practitioners and non-practitioners wonder: why are there many tai-chi coaches being over-weight? The truth is tai-chi is a very adaptive form of exercise (assuming no combat-type martial art training involved), one can adjust one’s calories burn through different vigor-levels of practice. And those who eat more than their fair share of calories burn will certainly result in gaining weight. Simple mathematics, as our nutritionists would have said.
The above is still not too problematic. The most harmful misunderstanding is that, as some practitioners or non-practitioners believe, through tai-chi practice, one will gain chi, and that chi will be stored at one’s belly, resulting in an over-sized body! “That is not fat but chi!” has been their belief! And some pointed out the inflating and deflating actions of a master’s fat belly being a demonstration of chi – without knowing that a slim body can also do, even better, such diaphragm movements!
Finally one reason why some tai-chi coaches like keeping a over-weight body, I speculate, is due to inertia and stability of a heavy body: a fatter guy is more difficult to be pushed away in friendly (or controlled) pushing hand matches. That's why sumo wrestlers are fat guys.
If you practice tai-chi and are over-weight, you can choose doing the more vigorous tai-chi exercises, or take advice from your nutritionist, or, better still, do both.