kenkou no tame ni, amai mono wo sukunaku simasu.

〜のために means for the sake of ~, for ~, or in order to benefit ~.

So:

• 健康 = health
• の = links the noun to ため
• ために = for the sake of / for

Together, 健康のために means for my health or for the sake of health.

In this sentence, it gives the reason or purpose for the action that follows.

Because 健康 is a noun, and nouns usually connect to ため with の:

• 健康のために = for health
• 家族のために = for one’s family
• 仕事のために = for work

Think of の here as the normal way to connect one noun to another noun-like expression.

You cannot usually say 健康ために.

In ために, the に is part of the grammar pattern. You should learn ために as one set expression.

It often marks:

• purpose: 日本へ行くために日本語を勉強します。
• reason / for the sake of: 健康のために運動します。

In this sentence, it means for the sake of health.

Because 甘い is an い-adjective, and in Japanese, adjectives come before the noun they describe.

So:

• 甘い = sweet
• 物 = thing(s)

Together:

• 甘い物 = sweet things

This is the normal word order in Japanese, just like red car in English rather than car red.

Literally, 物（もの） means thing, but in this sentence 甘い物 naturally means sweet things, especially sweet foods or sweets.

So depending on context, 甘い物 can mean:

• sweets
• sweet foods
• sugary things

It does not have to mean random “sweet objects.” In everyday Japanese, it often refers to food.

Also, もの is very often written in hiragana, so you may also see:

• 甘いものを少なくします。

That means the same thing.

Because 甘い物 is the direct object of 少なくします.

The pattern here is:

• X を 少なくする = to make X less / reduce X

So:

• 甘い物を少なくします = I reduce sweet things / I have fewer sweet things

The を marks the thing being reduced.

少なくします comes from:

• 少ない = few / little
• 少なく = adverbial form of 少ない
• する = to do / to make

So 少なくする literally means to make less or to make fewer.

In polite form:

• 少なくします

So the sentence is literally something like:

• For health, I make sweet things fewer.

In more natural English:

• I eat fewer sweets for my health.
• For my health, I cut down on sweets.

Because 少ないです just describes a state:

• 甘い物が少ないです = There are few sweet things / Sweet things are few

But 少なくします expresses an action or decision:

• 甘い物を少なくします = I will reduce sweet things / I make them fewer

So this sentence is about actively cutting down, not just describing a situation.

Yes, that is a very natural interpretation.

Literally, the Japanese says I reduce sweet things, but in context it usually means:

• I eat fewer sweets
• I cut down on sweets

Japanese often leaves some details unstated if they are obvious from context. The sentence does not explicitly say eat, but that idea is understood.

Yes, it is understandable and natural enough, especially for learners.

That said, native speakers might also say things like:

• 健康のために、甘い物を控えます。
  = I cut back on sweets for my health.

• 健康のために、甘い物を減らします。
  = I reduce sweets for my health.

Compared with those:

• 少なくします focuses on making the amount fewer
• 控えます often sounds a bit more natural for habits like food, alcohol, etc.
• 減らします is also very common for reducing quantity

So your sentence is fine, but there are other common ways to say it too.

Because Japanese often omits the subject when it is clear from context.

So even though English needs:

• I reduce sweets for my health

Japanese can simply say:

• 健康のために、甘い物を少なくします。

The subject is understood from the situation. In many everyday sentences, Japanese leaves out I, you, he, etc. unless they need to be stated.

It can overlap in meaning, but here it most naturally means for health or for the sake of my health.

If you specifically want to say in order to become healthy, Japanese often uses clearer expressions such as:

• 健康になるために = in order to become healthy

Compare:

• 健康のために = for health / for the sake of health
• 健康になるために = in order to become healthy

The first one is broader and very common in advice about lifestyle.

The spaces are only for learners. Normal Japanese is written without spaces:

• 健康のために、甘い物を少なくします。

Textbooks and beginner materials sometimes add spaces to make it easier to see the parts of the sentence.

So in real Japanese writing, you would normally not include them.