What diet best suits tri training?

Leona, I have to agree with MB.  A slight reduction in calories is probably going to be the way to go.  Radically cutting your carbs will make you feel cruddy and affect your performance, radically cutting your protien will affect your recovery and performance.  And just plain not eating enough calories will make your feel cruddy, affect your recovery AND hinder your performance!  So the trick is to get just enough to eat without overdoing it.

Try eating small meals 5 times per day.  Make sure you get a good mix of carbs, protein, fat.  Don't cut way back on carbs.  Eat a good solid breakfast, it'll help you keep going for the first 1/2 of the day.  Without breakfast, you tend to "binge eat" at lunch and dinner, overdoing things.  Your glycogen stores are depleted in the morning, after having gone all night without eating.  Priority #1 is to top them off in the morning.  Stick with more complex carbs, like brown rice, whole grain breads and cereal, etc.  Eat plenty of fruits and vegetables.  Use common sense and it won't be necessary to follow any sort of regimented diet.

I have found that eating as natural as possible; fruits,veggies, grains, and lean protein has helped my recovery from my increase in training for triathlons.  I have cut down on, for the most part, preservatives, trans fats, sweetener, caffeine and a whole host of the "typical" american diet foods.  I am not perfect at it, but my overall health has really improved without the coffee, chips, fries, cakes and sweets and all of the other junk I used to eat daily. 

I  start with a shake in the mornings made of organic fruits, soy milk, soy protein mix and ice.  It is very tasty.  Drinking the shake in the morning seems to keep me on the healthy eating habit throughout the day. 

I hope this helps. Good luck.

Mollie