Brief Answer:
hi

Detailed Answer:

Hello Mr Aayush,

Thank you for your query. I understand your concern. Good to hear that you are into regular exercise to keep yourself fit and healthy.
Agree increased protein intake is important for building muscles during gym.
Well i feel natural protein intake is very important and good source and healthy too without side effects.
Avoid taking artificial over the counter protein supplements unsupervised.
Good dietary sources of protein are
Eggs, meat, fish.
Vegetarian sources include daily products like milk, yoghurt, chese, paneer. Nuts beans and legumes. Also soy products like tofu is a very good source.
some protein supplements like ensure plus, peptamen powder, threptin biscuits are also well balanced source without side effects preferably to be taken under medical supervision.
Some of these protein supplements commercially available are likely to aggravate diarrhea (though low chances with the once i have mentioned above). also vegetarian protein supplements i mentioned above are unlikely to cause diarrhea.
hope i am able to answer your query satisfactorily.
please let me know if you have more queries if any.
best wishes.

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