A. Most of the protein powder or weight gain supplements are prepared from herbal ingredients & do not have any side effects if taken in the optimum dose.
However, before choosing any such health supplement, it is advisable to consult your family physician once.
Also make sure they do not contain steroids
...as intake of such a supplement will cause harm in the long run.
B. These products are only dietary supplements & should not compromise on routine healthy food such as:
1. Consume more of natural diet like fresh fruits, green vegetables, milk, eggs, wheat, etc.
2. Avoid oily and junk food.
3. Stay away from smoking
Best is to stay active, exercise regularly, avoid stress
, get good sleep, think positive and stay happy.
Wish you a healthy life.