Check the GCN channel on YouTube for their recent fasted riding tips. The theory is to kickstart the body into burning more fat when it thinks no carbs are coming.
If you're not sure you can handle riding 60-90 minutes at a low to moderate effort without having eaten for 8-12 hours, try it on an indoor trainer first. That's how I do most of my fasted rides, although I'll occasionally do them outdoors since I know I can handle it after working up to it very carefully.
If I do fasted rides outdoors it's only on familiar routes so I know the appropriate effort based on speed rather than how I feel. I may feel fine but if my top speed at maximum effort on a certain route is 18 mph and a good workout is 16-17 mph, I shouldn't be going anywhere near that on a fasted ride. Ditto on the indoor trainer -- no intervals, no sprints, no standing to pedal other than to stretch the legs for a few seconds, etc.
Or carry quick energy snacks and plenty of water. At the first sign of a low blood sugar bonk, stop for 15 minutes, eat a snack and drink plenty of water before continuing. Bonk symptoms vary for different people, but can quickly escalate from feeling peckish to growling stomach, feeling anxious, then irritable and lightheaded, even irrationally angry out of proportion to circumstances (hangry), headachy, dizzy, weak, trembling and faint. If you haven't experienced these before you may not have any problems. But once you've experienced the symptoms you'll know what to watch for next time.
I've pared off a couple of pounds of the most stubborn fat, the stuff around the middle that lingers after we've trimmed the rest of the body. But it's easy to go overboard so be sure you're in good health. I'm recovering from a shoulder injury and thyroid problem, so my efforts are relatively low compared with what I'd do normally.