It really depends how long you do it for, for what intensity. You've got to be careful that you're not burning the candle at both ends, so to speak.
If you're trying to build a few pounds or hold onto the muscle you have, then it can have an impact.
Try to keep it to a relatively low intensity and limit it to, say, half an hour once or twice per week. Also take in an extra 100 or so calories immediately afterwards, then you should be able to keep any potential negative effects at bay.
