Do you weight more when you flex your muscles?

Not you but your muscle for sure. It is simply logic as and you flex your muscle there is a similar thing happening in your body.

Your bloods and cells circulation is moving so well and more that your muscle, like in doing cardio session will be more full of circulation and flexible. Automaticaly your muscle will be heavier and stronger .

Six pack abs have no functional use, then why are they so sought after?

Hi Arun,Kindly allow me educate you a bit on the human anatomy (science that studies the human body) and kinesiology (science that deals with how the human body moves) Once you understand this concept then I may not need to answer your question.I am sure you have heard

Why can't I gain weight?

May be due to fast metabolism system.These 5 yoga poses helps to gain weight fastly :-Top 5 Yoga Poses To Gain Weight That Actually WorksThere can be several reasons for this :-Poor eating habits.Fast metabolism system.Poor lifestyle.Overwork or stressGenetical problems.Some health issue.