"If I ate more, I would be stronger."
Translation:לוּ הייתי אוכל יותר, הייתי חזק יותר.
To add another idea to this discussion - looking at it from the opposite direction:
- "if I were to ..." feels like quite a satisfying match here.
Of course, the two languages don't always correspond with perfect precision to each other, but there can often be certain types of construction that can work quite nicely.
[EDIT] even better, although a little more long-winded:
- "If I were to have eaten more ..."