Question: Should I work in my fat burning zone to lose more weight?
Answer: The idea that you burn more fat in your 'fat burning zone' (or at the lower end of your target heart rate zone, about 60% to 70% of your maximum heart rate) has been around for years and it comes from the idea that, at lower intensities, your body relies more on fat stores for energy. On the surface, this seems like it would lead to more fat loss but the opposite is actually true.
In reality, you do burn a higher proportion of calories from fat during low-intensity exercise...but, you burn more total calories during high-intensity exercise and it's the total calories that matter when it comes to weight loss, not the percentage of fat or carbs used.
Does that mean you shouldn't do low-intensity exercise? Not at all. You can still burn calories, although you may need to workout longer to burn the same number of calories as high intensity exercise. Both high and low intensity exercises have a purpose and having a variety of workouts with different levels of intensity is a great way to challenge different energy systems in your body and train different aspects of your health and fitness.
And, remember, losing weight is also a function of what you're eating so tracking your calories and making sure you're eating less than your burning is another way to ensure you're losing fat.