After coming across these Ant-Man questions,
I tried to remember if it was ever explained how Bruce Banner, aka the Hulk, gains and sheds mass.
In the 1960s Hank Pym
discovered and isolated a rare group of subatomic, extra dimensional particles, which became known as "Pym Particles", that could increase or decrease the size and mass of objects or living beings by shunting or adding it from a subatomic dimension.
Pym Particles have the capability to alter the scale, mass, strength and density of organic and inorganic subjects
Even though Pym Particles haven't been mentioned before Ant-Man, could they still be a possible explanation for how the Hulk gains/shed mass?
Is there a MCU explanation for where the additional mass comes from when Bruce Banner transforms into the Hulk?
If not, is there anything in the previous movies that would contradict the theory that Pym Particles are somehow involved?