How can i gain weight in a fast but healthy way?

Ok, so I am not annorexic, AT ALL. I actually eat quite a bit, and no, I do NOT force myself to throw up, or nothing stupid like that. But anyways lets get to the point, I eat nromal meals, I do eveyrthing, like a normal person should do, but I just...

cannot gain weight, I sometimes even loose weight. And my doctors say my weight is unhealthy ( I do not want to say my weight ) but I dont get it, why am I loosing, or staying the same, instead of gaining? I am happy to not be fat, but im tired of being asked if im annorexic. So anyone know how to gain weight fast? but healthy, of course.

Well since you don't want to say you're weight or anything I'll give you the resources to figure out some simple calculations that will help you.

YOUR VITALS
A. Your Weight in pounds ___
B. Multiply A by 11 to get your basic calorie needs (how much your body burns just by existing) ___
C. Multiply B by 1.6 to estimate your resting metabolic rate (rate of calorie burn when you factor in daily activities) ___

YOUR EXERCISE
D. Aerobic Training - Multiply the number of minutes per week that you run, cycle or play sports by 8 ___
E. Strength Training - If you're doing a total body exercise plan, add 600 to your answer from D. If you're doing 3 sets, add 840 to your answer from D. ___
F. Divide that by 7 ___

YOUR CALORIE NEEDS
G. Add C and F to get your daily calorie needs ___
H. If you're happy with your weight stop here.
Otherwise, subtract 500 from G ___
This is your estimated daily calorie budget if you want to lose 1 lb per week. Subtract 1,000 to lose 2 lbs per week. Anything more and you'll be losing more muscle than fat.

***Now all you need to do is ADD instead of subtract. Add 500 to your daily calorie budget to gain a pound a week. Or 1000 to gain 2 pounds. Anything more than that and it'll be unhealthy. Remember though, that although you're trying to gain weight - what you eat still needs to be healthy.

I was thinking the same the a few days ago. I also am a weed, although i eat quite alot. The thing i discovered, was that i'm eating all my food in one binge. Try eating three average sized healthy meals; Breakfast, lunch and dinner. All well-spaced out.
If you haven't already been doing this, then you may find it hard to eat at those three times, seeing as your body won't be used to it.
But give it a go anyway

The basic principle is that you need to eat more calories then you expend. Eating the right foods and eating more often is fundamental to gaining weight. Eating more when you don't eat much as it is can be hard, so I suggest increasing your meal frequency but eating less at each meal. You diet should consist of high protein foods, high carbohydrate foods, and good fats. A great website for gaining weight is http://www.gainingweight.info/