o.k.
the only thing that i am aware of that will increase your metabolism is exersize... lets think about it, if you take a person that does no exersize at all other than daily functions and give him his caloric matience of lets say 2,000 calories in 6 meals rather than 3 what is it gonna do for him as far as increasing metabolism? notthing... some might argue the fact that digestion burns carlories, and it does, but nothing your gonna see a difference from... you would probably burn the same amount from laughing your ass off at a few jokes at work!
the only reason why 3 big meals a day would make a person gain weight is insulin response from a large amount of carbs being consumed at one time, this in my book would not be the best way to go, plus your blood sugar is all over the place and you are tired and lethargic most of the time.....
what will increase your metabolism is exersize, weight training or cardio can do this.... now if you have a fast metabolism and your trying to gain lbm it can be tuff, but not a bad thing in most cases if you look at it the right way... increased metabolism= increased protein synth.(in most cases) thats a good thing, that means mnore of the protein you consume can be used for building muscle!
now the way i see it if you have a fast metabolism you need to consume more calories, so the trick is finding nutrient dense foods that will not slow digestion too much and bloat you too bad.... the trick that i found to work very well is oil.... I use coconut oil, mac. nut oil, and olive oil to make up for caloreis i need to grow... its easy, take 2 tbsp of oil with every meal through out the day, in most of these there is 12-14 grams of fat (good fat) per tbsp roughly 120 cal, so by adding 2 tbsp per meal you are getting an additional 240 calories per meal and with 6 meals a day thats 1,440 calories extra from taking 2 little tbsp's of oil with each meal... now make sure your protein and carbs are correct and enuf to grow and this is pretty much fool proof...
make sure to take some good digestive enzymes as this have extra demands on your stomach and to create its own, hope this helps.. good luck