high carbs.. high fat.. low calories?

It's not ideal since you'll have to consume very low protein levels in order to do this. You can still lose weight with this approach but you'll be much better off increasing protein at the expense of carbs.

First up, the only solidly proven 'unhealthy' fat is trans fat. Fat is demonized by the media and it's very easy to buy into it all, but a moderate balance of saturated (yes, saturated!), monounsaturated and polyunsaturated should cause you no significant health issues at all. There's evidence that eating a lot of red meat has cardiovascular effects and people jumped to the sat fat hypothesis but there are simply too many other confounding factors in a western high red meat diet to really say. Conversely, look at the inuit diet - very high fat, very high protein from non-red meat sources and they're pretty steaming healthy. So yep, don't be scared of fat. Nuts, peanut butter, olive oil, fatty fish... all that good stuff will help you get your calories up higher.

I totally agree with Sidesteal (but then, I always do because the dude really knows his stuff), about increasing protein at the expense of carbs. Protein and Carbs both have about the same amount of calories per gram (roughly 4), but whereas there's a lot of strong evidence out there that too many carbs may have adverse health effects, protein is pretty much universally accepted as the "healthiest" of the three macros. High protein diets will help your body to minimize lean tissue loss while you are on a calorie deficit - i.e. it will help to maintain and rebuild the muscle that your body cannibalizes for energy (when on a calorie deficit you don't only lose fat).

Hope that helps.

how many fat grams are you averaging per day, total?