Insulin/Fat Adaptation

I understand that waiting between meals helps our bodies access stored fat. What if I’m sipping on diet soda all afternoon? Is this enough energy I’m giving my body, that it doesn’t have to use my fat storage? Or can I still be fat adapted if drinking it over several hours. I just take forever to drink it. I know it’s not “good” for me but I haven’t given it up yet and I’m wondering if I’m messing up my hormones (insulin balance etc) by not drinking it all at once and being done, allowing for time with no food or drink between meals. Does that make sense? I also do this with lemon water and stevia. Is this ok for fat adaptation?

Also, if I understand right, vegetables are still carbs but will affect insulin much less. But if I’m eating veggies throughout the day, am I still keeping the “fridge” full, like Brooke says in her fat adaptation webinar?