If by weight gain shakes you mean protein shakes then it depends on what your goals are. They can add calories to your diet, yes, but since they are largely protein it won't trigger the same response as say a chocolate milkshake. The carbohydrates/sugar in a regular milkshake would spike your blood sugar and trigger an insulin response, which in turn would store more fat per calorie then if it was all coming from protein. This does lead to a higher risk of diabetes and other complications however. A protein shake on the other hand would simply increase the volume of calories which would cause weight gain as well, but at a much more reduced rate.
tl;dr
Protein (weight gain) shakes: Healthier slow gain.
Regular sugary shakes: faster gain but with more risks for health complications later on if you don't plan on eating a protein based diet.
tl;dr
Protein (weight gain) shakes: Healthier slow gain.
Regular sugary shakes: faster gain but with more risks for health complications later on if you don't plan on eating a protein based diet.
12 years