"I must eat, too."
Translation:Je dois manger, aussi.
"I must eat, too." can mean two things: 1. someone else ate before me, and now "I too have to eat" (Moi aussi, je dois manger.) OR 2. I have done something else before eating and now "I have to eat, too" (Je dois aussi manger) before moving on to other things. Each understanding requires a larger context. "I have to eat, too" can mean both 1. and 2.
"must" is an absolute obligation, and "have to" and "need to" are less imperative.
But all three can be translated with "il faut", an impersonal phrase using "il" as a dummy subject (never translate it to "he").
"il faut manger" is really impersonal because we do not know who has to eat. Therefore, you can interpret it as "one has to eat" or "we have to eat" or "you have to eat", depending on context.
"il nous faut manger" concerns "us" = we [must/have to/need to] eat
- "il me faut manger" = I [must/have to/need to] eat.
The other way round, when you get an English sentence with an obligation, you can translate it to an "il faut" formula.
- you need to eat = il te faut manger / tu dois manger / tu as besoin de manger
Note that "need to" is very frequent in English but in French much less.