What do you call such kind of food/drink?

If we feel tired or weak, we have some kind of food like chocolate or tea to make ourselves active or fresh. Is there any particular word or phrase for such food?

You might call it a "pick-me-up."

"invigorating" is the word I would use.

• "An invigorating drink/cup of coffee."

• invigorate - "to impart vigor, strength, or vitality to; animate"

"A few whiffs of the raw, strong scent of phlox invigorated her" (D.H. Lawrence).

"The bright sun and invigorating northern air made me feel much better"

but you might also use "energizing"

• "energizer" - "something that gives energy to, activates or invigorates.

"I feel so slow today, I guess I need an energizing drink"

Anything in general that restores energy is a restorative, such as "a restorative piece of chocolate" or "a restorative nap." I disagree slightly with the suggestion of refreshment since that's passed into a more general sense of any food or beverage, especially that provided to guests, but the literal meaning is there. A stimulant potentially carries connotations of being pharmaceutical, but not always (e.g. caffeine is a stimulant, but so is a nice hot cup of coffee).

As far as adjectives go, "invigorating," "revitalizing," "energizing," and "rejuvenating" can all be used to describe any food that provides that effect to the describer. I think you may be looking for a noun that describes a genre of food generally accepted to be used for that purpose, and to that end I recommend "pick-me-up" (colloquial) or "restorative" (the most natural of the nominalized adjectives, to my ear).

I'll go with stimulant and stimulating [food or beverage].

stimulant: any food or beverage that stimulates, especially coffee, tea, or, in its initial effect, alcoholic liquor.

Random House Dictionary

Also, you might want to say, I need a cup of strong, hot tea (or coffee or whatever) for a kick.

kick: the sudden stimulation provided by strong drink (or certain drugs); a sidecar is a smooth drink but it has a powerful kick

Princeton University, Farlex Inc.