On the point of higher carb - lower fat diets improving fat loss and whatnot, I think there was some research done recently that has shown that it doesn’t really work like that as your body will adjust which resources it’s going to burn based on what you eat and in what proportions. What this means is that on low fat diets you will be burning appropriately less fat.
As for retaining energy during training, I drink a mix of water, fructose, dextrose, and BCAAs. Also, there was a paper that suggested a correlation between satiation and protein intake in a meal (i.e. you will feel more “full” if you eat more protein, particularly during low calorie diets) so you could try that. link to paper
Also if you do weight training you should account that into your caloric calculations (rule of thumb is 60 min of strength training is about 250 kcal, however, this will vary with intensity, rest periods, etc.)