For one day, it's no big deal. And oatmeal is a whole grain (although quick/rolled oats would be better than instant and really aren't much harder to make), so it's the good kind of carbs. And even instant oatmeal has around 4g of protein and 3g of fiber per serving (depending what brand you buy and what the manufacturer considers a serving to be). But you don't want to eat like that every day, of course

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