The problem is that theycurries have a lot of calories.

It's not clear to me what "they" references, since the previous sentence has only singular nouns.

EI get even more calorieso if I have a curry with a cutlet.

Your sentence is incomplete and I didn't understand what exactly "Even more so" referred to.

I'd eat curry at every meal if I could and. I actually ate it every day when I was in college.

Gingerbreadwoman made a separate suggestion ("...,and I actually did eat it..."). But you could also change it into two sentences and it would also sound fine :)

The problem is that thecurry usually haves a lot of calories.

You can use the singular word "curry" to refer to "types of curry" in general. We often use the singular form when we talk about a dish in general.

I added the word "usually" to show that while it is typical for curry to have a lot of calories, different types of curry may have different numbers of calories. Adding "usually" here makes the sentence sound a bit more natural to me.

Even more so if I have a curry with a cutletfor Katsu Curry.

The meaning of this sentence is currently "If I have curry with a cutlet, it has more calories". However, the number of calories in the curry does not change whether you eat it or not - the number of calories depends on which type of curry it is. So what you are trying to say is "As for curry with a cutlet, it has more calories". (Or more simply: "Curry with a cutlet has more calories.")
If we write out the correct sentence in full, it would be "The problem is even more so [for/with] curry with a cutlet". You can use "for" or "with" here, but as we're already using "curry with a cutlet", it looks better to not repeat this word too many times and just use "for".

You could also say "Especially curry with a cutlet" - this makes it a lot simpler! "Even more so" is more formal.

Finally, in English we actually have the term "Katsu Curry". You can use this to be a bit more specific and help the reader understand which type of curry you're writing about. You can use it with or without capital letters. However, I recommend using capital letters, as some people may not know what "Katsu Curry" is, and capitalising helps the reader understand that it is a specific type of dish.

But I don't want to give up eating curriesy.

Again, for talking about "curry in general", you can use the singular form - "curry".
I added "eating curry" so that it is clearer.

The problem is that ithey haves a lot of calories.

Even more so if I have a curry with a cutlet.

But I don't want to give up curriesy.

I'd eat curry at every meal if I could, and I actually did eate it every day when I was in college.

The way you wrote it is not wrong, but the way I corrected it emphasizes the connection between the first part of the sentence and the second part.