Chances are you burning more calories than you are putting in. The complex carbs will help with that, and the other is to eat a lot of protein.
Your cardio is going to be good with sparring, and if you do your circuit training right you can still use high weight/lower rep, and Olympic lifts to essentially do your strength training for you.
Keep in mind lifting for athletics means building lean, fast twitch muscle, which tends to not be bulky.
The idea should be putting on more muscle mass in order to gain weight. In order to do that you need more calories, and a lot more protein. You should be eating 5 to 6 times a day, and ensuring that for 4 of those meals you are taking in 20grams or so of protein. (Eating much more than 20 grams of protein in one meal is a waste, your body can only metabolize so much protein at a time, so avoid any sort of protein powder/bar that claims 40 or 50 grams of protein...)
I don't know your weight/height/age/body composition to really get too in depth.
But in general, focus heavily on strength building, perhaps by either catering your circuit to Olympic style lifts, or forgoing circuit training to do more superset Olympic workouts.
You can lift like this on training days, but ensure you have some key time to rest.
(Edit: KW: Just poking around, same ol same ol.
Eat more food. That is it.
My question is that how do i maintain or increase my weight without loosing it? I'm going through extensive training right now and i lost more than 1/5th of my weight. I've been doing circuits and sparring non stop as well as lifting. But my weight keeps dropping. I tried lifting and training on the same day but my body couldn't take it. I would always vomit. If you need more details. I'm around 6 to 7 % body fat and i can lift around half or more of my own body weight. If anyone can give me some good diet or advice it'd be great. Thank you.
