Learn Spanish (Spain): Como engullas la comida, te sentirás peor. - If you gobble the food, you will feel worse.

Using como followed by the subjunctive is a common way in Spain to express a condition that carries a warning or a mild threat. While si engulles is a neutral condition, como engullas implies 'if you gobble... beware, you will feel worse'.

Why is engullas in the subjunctive mood rather than the indicative?

When como means 'if' (for warnings), it must be followed by the subjunctive. If you used the indicative here (como engulles), the meaning of como would completely change to 'since' or 'because' (Since you gobble the food, you will feel worse).

Could I use the future tense for the condition, like como engullirás?

No, just like with si clauses, Spanish does not use the future tense right after conditional words like como in this structure. The condition itself uses the present subjunctive (engullas), while the consequence uses the future (te sentirás).

Do I ever need to use más before peor?

No, you should never say más peor. Because peor is already the comparative form of mal (badly), adding más would be grammatically incorrect, much like saying 'more worse' in English. It always stands on its own.