When you gain weight does it really go everywhere? is it evenly spread? or is it true that it could be just in certain areas like stomach, legs, etc.?

Not evenly spread: Different parts of the body store the fat, not in the same amounts. It depends partly on a person's genetics (members of the same family have similar body shapes), and on one's hormones plus dietary choices. Also, if a person had liposuction and sucked out a lot of fat from one part of the body, but she kept on eating and eating, she would then store fat in other parts of her body.