okasi wo tabesugiru to, hutorimasu.

を marks the direct object of the verb, meaning it shows what is being eaten.

So in:

お菓子を食べすぎる

the thing being eaten too much is お菓子.

A native-English way to think of it is:

• お菓子 = sweets / snacks
• を = marks the thing acted on
• 食べすぎる = eat too much

So the whole part means to eat too many sweets or to overeat snacks.

お菓子 usually means sweets, candy, snacks, or treats. The exact translation depends on context.

It can include things like:

• candy
• cookies
• cakes
• snack foods

The お here is an honorific prefix that often appears in everyday words. In this word, it is just part of the normal vocabulary item お菓子, so learners should usually memorize it that way rather than thinking of it as optional every time.

食べすぎる is made from:

• 食べる = to eat
• すぎる = to exceed / to do too much

So:

• 食べる → 食べすぎる
• to eat → to eat too much

This pattern is very common in Japanese.

Examples:

• 飲みすぎる = drink too much
• 働きすぎる = work too much
• 買いすぎる = buy too much

With る-verbs like 食べる, you usually remove the final る and add すぎる:

• 食べる → 食べすぎる

In grammar terms, it functions as a single verb expression, even though it is built from another verb plus すぎる.

So in this sentence, you can treat 食べすぎる as meaning to overeat or to eat too much.

It behaves like a verb and can be conjugated:

• 食べすぎる = eat too much
• 食べすぎた = ate too much
• 食べすぎない = do not eat too much
• 食べすぎて = eating too much, and...

Here, と is a conditional particle meaning something like:

• if
• when
• whenever

In this sentence:

お菓子を食べすぎると、太ります。

it means:

If you eat too many sweets, you gain weight or When you eat too many sweets, you gain weight

This と is often used for natural results, habitual results, or results that regularly happen.

So it fits well with cause-and-effect statements like:

• 春になると、暖かくなる。
  When spring comes, it gets warm.

• このボタンを押すと、ドアが開きます。
  If you press this button, the door opens.

All of them can relate to if/when, but they are not used in exactly the same way.

In this sentence, と sounds natural because the speaker is stating a general consequence:

• If you eat too many sweets, you get fat

That is a typical, predictable result.

Very roughly:

• と: natural, automatic, general result
• たら: if/when something happens; very flexible
• なら: if it is the case that / if you say that

So お菓子を食べすぎると、太ります sounds like a general truth or tendency.

If you used たら, it could sound more situational:

• お菓子を食べすぎたら、太りますよ。 If you eat too many sweets, you will gain weight.

That is also possible, but と is especially good for a general rule-like statement.

太ります is the polite ます-form of 太る, which means to gain weight or to get fat.

Japanese often uses polite form in ordinary statements, especially in:

• textbooks
• neutral explanations
• conversation with people you are not very close to

So this sentence is polite and natural.

The plain form would be:

お菓子を食べすぎると、太る。

That is less polite and more casual.

That is because the verb before と is inside a conditional clause, and dictionary/plain form is normally used there:

• 食べすぎると

The main sentence then ends with the polite form:

• 太ります

This is very common in Japanese. The politeness usually appears at the end of the whole sentence, not inside every clause.

So a pattern like this is normal:

• V-plain + と、main clause in polite form

Example:

• 朝ご飯を食べないと、おなかがすきます。
  If you do not eat breakfast, you get hungry.

Japanese often leaves out the subject when it is clear from context or when the sentence is meant as a general statement.

So 太ります does not explicitly say:

• you gain weight
• people gain weight
• one gains weight

Any of those may fit depending on context.

In English, we usually need a subject, but Japanese often does not. Here, it is best understood as a general statement such as:

• If you eat too many sweets, you gain weight
• People gain weight if they eat too many sweets

It can mean either, depending on context.

Common translations are:

• to gain weight
• to get fat

In many learning contexts, gain weight is the safest translation because it often sounds more neutral in English.

So:

• 太ります = gain weight / get fat

It sounds like a general truth, tendency, or repeated result.

Because of 食べすぎると, the sentence feels like:

• If you eat too many sweets, you gain weight
• Eating too many sweets makes you gain weight

It does not sound like one single past event. It sounds more like advice, a warning, or a general fact.

The comma is mainly there to make the sentence easier to read. Japanese punctuation is often more flexible than English punctuation.

So:

• お菓子を食べすぎると太ります。
• お菓子を食べすぎると、太ります。

Both are fine.

The comma helps show the break between the if/when clause and the main result.

Yes. 食べすぎる itself just means eat too much. The object tells you what is being overeaten.

So:

• お菓子を食べすぎる = eat too many sweets
• ご飯を食べすぎる = eat too much rice / too much food
• 夜に食べすぎる = eat too much at night

The verb does not contain the idea of sweets by itself. That comes from お菓子.

Yes, in the right context. Japanese often omits subjects, so context can supply I, you, or people in general.

However, without context, the sentence most naturally sounds general, like:

• If you eat too many sweets, you gain weight
• Eating too many sweets causes weight gain

If the speaker is talking about themself, then I could be the best translation.

The idea is the same, but the form changes a little depending on the word before it.

With る-verbs:

• 食べる → 食べすぎる

With う-verbs, you usually use the verb stem:

• 飲む → 飲みすぎる
• 読む → 読みすぎる

With い-adjectives:

• 高い → 高すぎる = too expensive / too high

With な-adjectives:

• 静か → 静かすぎる = too quiet

So すぎる is a very useful pattern meaning too much or excessively.

Because the sentence is centered on the action and result rather than setting up a topic with は.

The object is marked with を:

• お菓子を食べすぎる

Then the result follows:

• 太ります

You could make お菓子 the topic in some other kind of sentence, but here the basic object marking with を is what you need.

So this sentence is simply structured as:

• object + verb
• if/when that happens, result

Yes, that would be wrong in this sentence.

食べる normally takes a direct object, so the thing eaten is marked by を, not が.

So:

• お菓子を食べる = eat sweets

not:

• お菓子が食べる

Using が would make お菓子 look like the subject, as if the sweets are doing the eating, which does not make sense here.

It is natural and easy to understand. It sounds like a textbook-style general statement or warning.

A native speaker might also say similar things like:

• お菓子を食べすぎると太るよ。
• お菓子の食べすぎは太る原因になる。
• お菓子を食べすぎると太っちゃうよ。

But the original sentence is perfectly normal, especially for learners, explanations, and neutral statements.