I had the same problem the first week, I am still really new. However, when I lessened the grains and upped my veggies it all started to turn around. Although whole grains are great the carbs can still drag some people down into sleepy land and the veggies are really the key to sking improvement because of all those vitamins.
I agree with Libby... bump up the whole grains. And with all that excercise, your body may be craving PROTEIN! Beans, quinoa, oats, nuts,...yum. Has made a big difference for me. On the flip side, I start to feel crappy when I get lazy on the protein intake.
I've been vegetarian for 6 months now. I feel better but haven't had any weight loss. I feel "lighter" and have better digestion. I think its really easy to eat badly still if you have dairy or lots of substitutes. Exercise and a diet high in fruit and veggies is key I think.
I think dairy is the key, at least for me. I've cut out all animal products for a week, definitely went through some detox there on the dairy. After a week, I ate some fish and some eggs, because I was curious to see my body's response (these are the things I don't think I am willing to give up forever). Neither of these gave me any trouble. But today, I had a bagel with cream cheese, and I felt awful! After just a week of no dairy! I was crabby and gassy and tired. It's really hard, but try to give it up, if you can.