你一点儿都不胖。

Nǐ yìdiǎnr dōu bù pàng.

You're not the least bit fat.

我长胖了，要减肥。

Wǒ zhǎngpàng le, yào jiǎnféi.

I'm grown fat, I have to lose weight.

我比你胖。

Wǒ bǐ nǐ pàng.

I'm fatter than you.