Brock Lesnar vs Shane Carwin: Why does Brock look bigger?

The fighters have what is called "weigh-in" before the fight. Most of the time it is the day before. They will dehydrate themselves to meet the weight requirement for there class. Once they meet weight requirement they can rehydrate themselves and eat whatever they wish. That is the reason they look bigger during the fight. Water accounts for about 60-80 percent of your body weight. Once they rehydrate, they blow up again.

Because Lesnar IS bigger.

As a former High School and College wrestler, Lesnar has mastered the ability to cut large amounts of weight. Carwin most likely doesn't cut.

Lesnar walks around at 295, Carwin walk around at 280. They are both huge fighters, but Lesnar is a little bigger. Also, Lesnar's wrestling is better.

Simple. Lesanr is bigger by 20-30 pounds. He cuts 20-30 pounds before each fight to make the 265 pound weight limit. This is accomplished by not eating or drinking much the days leading up to the weigh in and sweating off a lot of water weight the night before or the day of the weigh in. Once he makes weight, Lesnar rehydrates and starts eating again.

This is common for all MMA fighters. Aside from the HW division, every fighter is bigger than the upper weight limit of their respective division. GSP walks around and 185 pounds or so but fight at 170. BJ Penn walks around at 165-170 pounds but fights at 155. It's not cheating as long as they make weight for the fight.

It all depends on Muscle mass and where the muscle is. It may be that Carwin's muscle is denser, and thus weighs more, yet takes up less physical space. I personally like Carwin much more. I doubt he will win, but I really dislike Lesnar's attitude and persona.

Because Brock is bigger.

He cuts weights, so during a fight he is over 20-30 lbs heavier.

It is possible to cut weight and gain it back in one day, it's a common practice fighters do, fighters like Sean Sherk and Matt Hugues gain 20-30 lbs in one day, Brock can cut even more weight.

The reason he looks bigger is because he is. He walks around at 300 to 310pds. The UFC weigh in his last two fights have given him nearly 48 hours to bulk up before fight time. That is more than enough time for him to get from 265 back to around 300 for fight time.

cause he cuts weight

however i hope Shane Carwin wins, he is strong, a great wrestler and actually has k.o. power

I think so too, Lesnar is just humongous! HW has no limit in weight!