Q: does dextrose powder help in gaining weight?

A: It'll help you gain lots and lots of fat. Dextrose is the more 'sugary' part of sugar (the other part is fructose) and really should not be part of anyone's diet. It is widely used in 'weight gainers' (see my Protein Supplements article) because it does put on weight quickly but that weight is going to be far more fat than muscle if you rely too heavily on it. A much healthier and more effective way to put on quality weight in muscle is to eat all the healthy foods, but simply eat A LOT of them so you gain weight. Fill out http://www.mikesfitness.com/content/fitnessguide and specify 'Gain Muscle' as your goal to see a sample bulking diet without any dextrose.