Nafsu makan Kakek berkurang.

Yes. Nafsu makan is a very common expression meaning appetite.

Literally:

• nafsu = desire, urge, appetite
• makan = eating / to eat

Together, nafsu makan specifically means appetite for food, not just desire in a general sense. So learners should treat it as a common set phrase.

Because Indonesian usually shows possession with the pattern:

thing possessed + possessor

So:

• nafsu makan Kakek = Grandpa’s appetite

This is different from English, where the possessor often comes first:

• Grandpa’s appetite

Other similar examples:

• rumah saya = my house
• nama anak itu = that child’s name
• buku guru = the teacher’s book

Capital Kakek usually suggests it is being used like a name or family title, similar to English Grandpa with a capital letter.

Compare:

• kakek = a grandfather / an old man
• Kakek = Grandpa

So Nafsu makan Kakek berkurang sounds like Grandpa’s appetite has decreased, where Kakek refers to a specific person in the family.

In general, kakek can mean:

• grandfather
• old man

But in this sentence, especially with the capital letter Kakek, it most naturally means Grandpa.

If it were lowercase, nafsu makan kakek berkurang, context would decide whether it means:

• the grandfather’s appetite decreased, or
• the old man’s appetite decreased

Berkurang means to decrease, to lessen, or to become reduced.

In this sentence, it describes what happened to the appetite:

• Nafsu makan Kakek berkurang = Grandpa’s appetite decreased

It is an intransitive verb here, so it does not take a direct object.

Compare:

• Harga berkurang = The price decreased
• Tenaganya berkurang = His/her energy decreased

In berkurang, ber- helps form a verb meaning something like to become reduced / to decrease.

For learners, the safest approach is to learn berkurang as a whole word meaning:

• decrease
• be reduced

You do not need to force a single simple English meaning for ber- every time, because its function varies from word to word. In this sentence, the important point is that berkurang works as the predicate: it tells us the appetite has gone down.

Because Indonesian often does not use a verb like is in the same way English does.

The sentence structure is simply:

• Nafsu makan Kakek = Grandpa’s appetite
• berkurang = decreased / has decreased

So Indonesian can say this directly without adding a separate word for is.

Also, Indonesian usually does not mark tense the way English does. Depending on context, berkurang could be understood as:

• decreases
• is decreasing
• decreased
• has decreased

In many real contexts, English would translate it as has decreased or is decreasing, depending on the situation.

Indonesian often leaves tense to context.

So berkurang by itself does not force one exact tense. It can be interpreted as:

• decreased
• has decreased
• is decreasing

If the speaker wants to make time clearer, they can add time words or aspect markers, for example:

• sudah berkurang = has already decreased
• sejak kemarin berkurang = has been reduced since yesterday / has decreased since yesterday
• sedang berkurang = is decreasing

Without extra markers, you rely on context.

Yes. A good basic analysis is:

• nafsu makan Kakek = subject noun phrase
• berkurang = predicate

So the whole sentence means that Grandpa’s appetite is the thing undergoing the decrease.

Normally, no. The natural possessive pattern here is:

nafsu makan Kakek

Using -nya would usually change the structure and meaning. For example:

• nafsu makannya berkurang = his/her appetite decreased

That sentence already has a possessor built into -nya, so adding Kakek after it would usually sound odd unless the whole sentence were restructured.

Natural options include:

• Nafsu makan Kakek berkurang
• Nafsu makannya berkurang if the context already makes it clear that -nya refers to Grandpa

Yes, it is natural and clear.

It sounds like a normal way to say that Grandpa is eating less or has less appetite. Depending on context, native speakers might also say similar things such as:

• Nafsu makan Kakek menurun
• Kakek kehilangan nafsu makan = Grandpa lost his appetite

But Nafsu makan Kakek berkurang is perfectly understandable and natural.

Both can work, but the nuance is slightly different.

• berkurang = decreased, became less
• menurun = declined, went down

With nafsu makan, both are common:

• Nafsu makan Kakek berkurang
• Nafsu makan Kakek menurun

Menurun can sound a little more like a general decline, while berkurang emphasizes that the amount is less than before. In many everyday situations, the difference is small.

This sentence already has a very standard word order:

• Nafsu makan Kakek berkurang

If you change the order too much, it may sound unnatural or change the emphasis.

A different but still natural structure would be:

• Nafsu makan kakek itu berkurang = That grandfather’s appetite decreased
• Kakek kehilangan nafsu makan = Grandpa lost his appetite

For learners, the safest choice is to keep:

• thing + possessor + predicate
• Nafsu makan Kakek berkurang

No. Indonesian does not normally use articles like English a or the.

So Nafsu makan Kakek berkurang does not contain separate words for them. Whether English uses the, a, or no article at all depends on the translation and context:

• Grandpa’s appetite decreased
• The grandfather’s appetite decreased

Indonesian leaves that kind of information unstated unless context makes it necessary.