The best advice I can give to gain weight is pretty simple...eat a lot! By a lot I really do mean a lot. 6 meals a day each containing 30grams protein at least, totalling 3500+ calories. You might even have to eat more than this. A good rule is if you aren't gaining weight, eat more.
As for training I wouldn't do more than 9 work sets for large bodyparts and no more than 6 on smaller bodyparts (I would recommend 4-5 on bi's & tri's) A common beginners mistake is overtraing, don't copy the workout's in Arnold's book because that would be massive overtraining.
Try to concentrate on the basic movements, ie squat, deadlift and Bench press, the main mass builders.
At your weight you should be able to pack on those pounds very quickly indeed providing you train sensibly, sleep well and probably most importantly - EAT EAT EAT!
Andy |