When I first started tai chi, I had been a couch potato and had reached size 20 (85kg). With the regular practise of tai chi and a little practise at home every day, I also changed how I was eating. The combination of gentle exercise and change in food habits meant that I lost weight slowly, until I reached my present size 14 (65kg).

I'm not a doctor or a diet specialist, but since my diet worked for me, I thought I'd share it here:

The diet I made up for myself was based on what I had read were anti-cancer foods (I'd had a brush with cancer), and cutting down how much I ate in the way of carbohydrates, as well as cutting out all fast foods. Concurrently, I upped the amount of veg in my diet, so that I now eat more healthily. But I'm not fanatical about it, I take weekends off to eat anything at all. I also cook my veg in bulk and then freeze it in ready portions in ice cream tubs, so that I can immediately have my five-a-day to hand, without that becoming a tedious chore...

During the week my diet looks like this:

Breakfast - a banana or an avocado

Lunch - a sandwich, usually salmon with watercress. This sandwich is my only carb of the day.

Evening meal: Veg with herbs and spices and either tofu or chicken
The principle is that I choose veg I like, not veg that I don't fancy, so no celery. Therefore I don't eat anything I'm going to hate, it's all good tasty stuff!
Veg I especially make a point of including are broccoli, carrots, aubergines and garlic, but others are added as I spot them in the market.
Spices I like to include are turmeric, ginger, paprika, cumin
I recommend buying spices in ethnic food shops, as you get them in larger quantities at cheaper prices!

Snacks: I make up a mixture, which I tote around and snack on whenever I feel  like it:
Almonds, pumpkin seeds, walnuts, brazilnuts, dried cranberries
70% choc - any less % and you are really just upping your sugar levels.

Supplements; calcium and vitamin D

It worked for me, so I hope you have similar success, if you want to try it!