To start, recognize that the bulk of your weight-loss is going to come from fasting, not from working out. Exercise will have other benefits, of course, like building and preserving muscle tissue, improving performance, and increasing endurance, but it won’t be where you’re really taking off the pounds. With this in mind, if your priority is to lose weight, you’ll need to be prioritizing meal planning over working out. As you start intermittent fasting, you may need to pull back from regular strenuous exercise, at least until you feel like your body is used to your new schedule.
When you eat a meal, your body spends a few hours processing that food, burning what it can from what you just consumed. Because it has all of this readily-available, easy to burn energy (thanks to the food you ate), your body will choose to use that as energy rather than the fat you have stored. This is especially true if you just consumed carbohydrates/sugar, as your body prefers to burn sugar as energy before any other source.