Answer:
The sentence is in the conditional tense, which is used to express a hypothetical situation or a possibility. The verb "manger" (to eat) is in the imperfect tense, which is used to describe an ongoing or repeated action in the past. The verb "être" (to be) is in the conditional tense, which is used to express a hypothetical situation or a possibility.
Therefore, the correct translation of the sentence is "If he ate a lot, he would be fat."