Is there any way to lower my metabolism?
Not really. But you can get around your metabolism's rate at which it can get rid of it's calories by shoveling in more nutrients then your body can burn off. Your body is more efficient at burning off fats and carbs than protein, that's why I put the emphasis on getting tons of extra protein in your diet.
Two points of doubt: (1) I have read that food consumed shortly before sleep or in the middle of sleeping tends to get turned into fat rather than muscle, so getting up in the middle of the night to have another protein shake does not sound like good advice to me. I think it can also lead to the development of acid reflux.
I just said that ectomorphs have a built in regulator of the overconsumption of calories, they cannot usually consume enough calories to have a conversion to bodyfat. The acid reflux is again, getting into genes. If you have the gene for acid reflux, then you will need to coordinate your diet accordingly, if you do not, which most people don't, then you have nothing to worry about. One knows for certain whether or not they are prone to acid reflux disease and it's nasty counterpart esophageal cancer, it is very painful and highly recognizable.
(2) None of the weight-gain mixes that I have used have had any significant amount of polyunsaturated fat or any other kind of fat in them. Optimum Nutrition Mighty One, for instance. (3) The carbohydrates in weight-gain powders are mostly in the form of maltodextrin, which is a complex carbohydrate: it is the main ingredient in corn starch. The nutritional label will tell you what proportion of the calories in a given mix are in the form of sugar. Of course, it is always a good idea to get as many of your calories from real food as you can, and your carbohydrates from whole grains rather than processed ones.
Sorry about the sugar thing. Nutritionists are currently classing carbs such as starches and sugars according to how fast they are metabolized into glucose (glycemic index). Maltodextrin is a polysaccharide that occurs naturally in complex carbohydrates like wheat and potatoes. Maltodextrin naturally occurs with other dextrins like soluble and insoluble fiber as well as gluten and amino acids. Eaten within the structure of a complex carbohydrate like wheat, maltodextrin can give a sustained release of glucose that gives wheat it's characteristic nutrition and fairly low glycemix index, hence it behaves like a starch when digested.
When Maltodextrin is isolated away from the other classes of Dextrins and proteins like gluten, it behaves like a SUGAR and has a high glycemix index rating, meaning that it is converted RAPIDLY into blood sugar like sucrose.
There are a lot of weight gain powders on the market, many contain soybean oil or coconut oil. In the late eighties and nineties, many weight gain powders removed the fat from their formulas because of the whole fat is bad campaign waged by nutritionists. A lot of those companies put the fat back in to reach the astronomical caloric values of 2500 - 3500 calories per serving (Hence, the South Park episode parodying the fictional supplement Beefcake 3000! lol!) Some did not, evidently Optimum Nutrition did... I have never liked that company, I always thought that they didn't have any research facilities and just bought bulk product and re-labeled it (which is what most companies do anyway! lol!)
I used to run a few GNC's back when I was a younger man and competed in two bodybuilding contests. I have always been a bit of a supplement and nutrition nerd.
As far as the genetic debate goes, I don't think that 19th century genetics knew a damn thing as compared to where we are now. The debate over whether we are activating our genes through environment or selecting them through breeding is a highly charged one. I don't think that they occur in isolation, I think that environment and natural selection are
both responsible for genetic development. My theories are just that, theories... but they are damn good ones and are not based on opinion, but on empirical evidence and personal experience.