No "sugar" is easy, no carbs is harder.
I've done 2 bodybuilding shows, so my max carb allowance was 12g a day for 12-16 weeks. And protein intake 300g a day.
My first show I went from 175lbs to 123lbs. 2nd show I went from 212lbs to 154lbs. And all while training max effort in the gym 5x a week and drug free (gear or clen like products).
I loved my cheat days. I could eat as much carbs as I want for 12 hours. The clock starts when ever, so I would do it in the morning like 7am-7pm. Cause I didn't want to waste time sleeping. I would often do 5 cups uncooked riced, 6 cans Aloha Iced Tea, 1 package somen noodles (the blue package), just no fats.
I was never a big dessert fan, but I love my rice. That is my Achilles Heel.
1 trick we used cause meal prepping sucks. Make Shoyu chicken and instead of sugar, use stevia or like product. Just dump the 5lbs bag chicken breast into a big pot with the ingredients and let it cook for like an hour. No need constant flipping of breast like if you were to grill or pan fry. This saved hours of cooking a week. Crock pot works even better.
When weight training and low carbing, the nice part is you can have as much sodium as you want. In fact, you need to increase it due to having no carbs to help retain water.
I used to work at a supplement shop and people would also over complicate dieting. It's simple math, burn more calories than you're intaking. So if you want to eat a pizza, go ahead, but you better be running like 20 miles that day. The easiest way to reduce calories is by cutting sugar/carbs.
Most people when they low carb it takes them a few weeks for their body to adjust and they don't feel like shit all the time. For me, I felt like shit during my entire diet period (12-16 weeks). So everyone responds differently. The other thing is the mind slows down with the lack of carbs. It was nice my old boss also competed in the 80's. So she would see me on days im really laggy and just tell me to go home. This helped a lot. She would also bring me food cause she knew what I was allowed to eat.
People also forget about the hidden carbs. Like teri sauce that has sugar in it, or katsu breading.