silly question about accidentally breaking fasts

Let's say I'm 8 hours into a fast and do have something small that technically breaks a fast (melatonin gummies, hard candies, gelatin capsules?) - do I have to restart entirely? Because as far as I know, they say you start burning from fat reserves by hour 12. So after a little accidental <20cal blood sugar spike, would I still burn fat 4 hours later? Surely, because I'd still be in a deficit?