How, you ask ?
Custom fitted, armour-plated exoskeleton with a working combination of motors and hydraulics at the joints.
The suit has a full-range of power:muscle ratio degrees ranging from "Regenerative" through "Unpowered" and "Neutral", finally to "Power Assist".
How to Use Your Exo-Skeleton:
Month
1:
Eat all you want. Recharge the suit nightly and when you put it on in the morning move the Selector into the "Neutral" zone. This mode compensates for the weight of the suit allowing you to move as freely as if you weren't even wearing it. As the days go by, slowly move the Selector towards the "Unpowered" zone. Do not attempt feats of SuperHerocity or SuperVillany during this time-period.
Month 2:
Eat all you want. Recharge the suit as required and when you put it on in the morning move the Selector into the "Unpowered" zone. This mode allows you to become accustomed to the weight of the suit without power assistance. As the days go by, slowly move the Selector towards "Regenerative Mode".
Month 3:
Eat all you want. Do not recharge the suit externally. At this point the suit will be your own portable fitness center. As the days go by move the Selector switch to varying degrees of Regeneration. Load your fitness program into the onboard computer and work those muscle-groups individually.
Month 4:
Eat all you want. Switch freely between Neutral, Unpowered and Regenerative as your normal needs dictate. When your PowerPack is topped up, start moving the Selector switch into Assist Mode. Learn how to use the up-to-10x Muscle Augmentation but don't forget to practice walking through doors without tearing them from the frame.
Practice in this mode until you feel competent enough to start your career as a superhero or supervillain.