I've had a friend face a similar problem. He was doing lots of high intensity martial arts training, both at class and and home, and wanted to diet down a few pounds without suffering performancewise.
Firstly let me tell you what his teacher told him: there's an advantage in coming to class fatigued. you have to learn to rely more on technique and less on your strength, which is really a big point in all martial arts. so you may want to consider it an advantage to have a period inwhich performance suffers.
Secondly, the way he ended up doing it was somewhat extreme. he chose 1 day a week and ate absolutely nothing in that day. a day of complete fast except water and maybe coffee. nothing, not even a salad. rest of the week he kept eating as much as he liked. worked really well actually.