Why? 为什么？

Why girls who yearns to get fats off their body tend to gain even more weight instead?

and

why guys like me, who tried so hard to pump fats into his body, lose weight more easily?

WHY?

i eat, and eat and eat...

Even be buddies with 食神，but still my kilos is not going up =.=

The graph is either constant or declining instead of going up, WHY? 为什么？