Thinking about katchup on a burger here…
Can I eat sugar as long as I keep to my macros?
Yes, you can eat ketchup as long as you stay within your macro limits.
There are also various options to regular (high carb) ketchup that are available, such as;

1 T is 20 g carbs. Then the rest of your food is zero carbs? I’d check your day’s menu to verify.
I personally would not. For me, that’s like giving an alcoholic a tablespoon of alcohol.
I would find an alternative like an herb butter, bacon, a good mustard, mayo, or pickles.
Once your tastebuds become more sensitive to sugar, you will recognize just how sweet ketchup is.
I have a bottle of “no sugar added” Heinz kechup in my refrigerator right now so I went and looked at the label. ONE GRAM OF CARBS PER TABLESPOON!
Yes, you can have kechup if you want kechup. Just read labels till you find one that is acceptable.
Have to agree. And I usually don’t like mayo on burgers or sandwiches. Just salads like tuna and stuff. But, on a cheeseburger I LOVE to mix mayo with some Frank’s Hot Sauce and spread it on and, OMG, the taste is amazing!!!
I’ve never had issues with small amounts of sugar, say in catsup or hot sauce. More than a few grams of pure sugar, like a bit of hard candy, does mess with me though, especially my GI tract. I seem to do better when it’s mixed in other things. But the word sugar, as opposed to any other carb source, is not an issue.
I tablespon is 20 cal/ 4 gm net carbs. Obviously those numbers don’t round out well, math wise. I guess I can only speak for myself, but if I put a teaspoon on my burger, that’s probably about 1.5 grams carbs and I can live with that.