Moving up and down in weight classes has been an issue for Ultimate Fighter champion Kelvin Gastelum since stepping into the octagon. That issue appears to be gone. Gastelum is starting to look right at home after being forced to move up to middleweight because of struggles to make weight at welterweight. He shared his jacked-up physique on social media:

Gastelum fought Tim Kennedy at middleweight last December in UFC 206, earning a third-round TKO over the veteran fighter. Kennedy would retire following the loss. 

It was a strong showing from a fighter who had a promising 5-0 start to his career stalled while bouncing between weightclasses. Gastelum's physical conditioning looks far ahead of where he was even then.

Next up for Gastelum is former champion Vitor Belfort, set to fight on March 11. UFC Fight Night 106 will be held in Brazil, featuring the five-round bout.

Belfort is a huge challenge for Gastelum, who made his mark as a light-heavyweight that can fight down to middleweight. It's a three-inch height difference in Belfort's favor. 

That size difference is only done justice by photo, via UFC's official Instagram page:

Gastelum could establish himself as a legitimate middleweight contender with a win over Belfort. Beating someone that projects well above his natural weightclass would be quite the feather in his cap. 

Gastelum, 13-2, could use this as a statement victory. Belfort is working toward bouncing back from a two-fight losing streak. It was a TKO loss when he stepped into the ring last, dropping his fight against Gegard Mousasi. 

Can Gastelum make up the size difference with his new physique? Let us know in the comments!