If I were in a controlled study for the improvement of arthritic joints I would be doing just one thing differently from before. But I am impatient and am doing two. I suspect most of us jump in with both feet when we get obsessed with making a real change, and I am no different.
So in addition to the yoga routines, I have changed my diet somewhat. I have been vegan for about two years, vegetarian for about 26. Vegan diets, like any other diets, can be healthy or not. I could try to live on french fries, for example. Vegan, but not healthy. Over the past several years I have slid into the use of more oil and more bread. Neither of these is necessarily unhealthy. Too much of either, though, can have a bit of an impact. So while I eat a lot of good, fresh foods - fruits and vegetables and grains - I have been shoveling in calories that aren't doing so much for me, and because my body is what it is, those calories have turned into extra pounds.
I do not apologize for my weight or feel guilty about it. I do not believe that I am "bad" or lacking in "will". I'll put my will against a host of thinner folks and likely come out ahead. But my body easily puts on pounds. This isn't the place to get into why my body more than that of somebody who has never been fat, so I'll leave it at that. The issue is simply that the extra weight puts more strain on my joints and causes increased pain and difficulty in moving and I'm sick of it.
So I have also moved to more of a McDougall-style diet. When I say "diet" I don't mean calorie-controlled, portion-controlled, any of that. I mean a way of eating. This way of eating means cutting out the oils that don't come naturally in the food. It means eliminating the white breads. Otherwise, it's a vegan diet based on the use of whole plant foods. I eat as much as I want.
I therefore expect that when I see improvements (note that I say "when", not "if"), they will come from both ends: from the yoga-style exercises and the change in diet.