These are questions I can't answer for you, I'm personally a big fan of working and training fasted as I have far more energy, although some people are distracted and light-headed when they haven't eaten... find out what works best for you.
Your Magic Caloric Number
A diet for building muscle or burning fat is useless if you haven't calculated your caloric intake (or if you've miscalculated it!).
Does your new diet have you in a caloric surplus? If so, you're going to be gaining weight.
Does your new diet have you in a caloric deficit? If so, you're going to be losing weight.
It is insanity to expect results without ensuring you're consuming the correct range of calories per day.
A magical 'fat loss food' does not exist. No food burns fat faster than any other food... there are foods that are lower in calories than others though.
You can check out my complete guide to calculating your calories based upon your goals here.
Whether Your Macro Breakdown Is Efficient
What's the deal when it comes to the proteins, carbohydrates and fats in your new diet?
There's many so called 'fad' diets out there, working with unrealistic macronutrient breakdowns.
Consuming all of your calories from proteins and fats is not sustainable in the long run, especially if you value your performance in the gym or as an athlete.
At the same time, if your protein intake is non existent or extremely low you're going to find yourself struggling to maintain any muscle mass you may have, let alone build any additional muscle.
If building or retaining muscle is your goal, you're going to need to consume at least 30% of your caloric intake from protein.
If performance and energy are your goal, you're going to need to consume at least 35% of your caloric intake from carbohydrates.
For brain and hormone health, at least 20% of your caloric intake should come from healthy fats.
The key point here is don't follow a diet that has macronutrient geared to a goal completely different to your own.
If The Diet Is Realistically Sustainable For You?
If your diet is overly strict, a daily struggle and what you deem unsustainable perhaps a few more adjustments are needed...
You'll get few results if you're following an extremely strict diet, then binging every few days as you can't maintain that level of discipline.
Consistency is key, if need be consume a few more calories, schedule in a cheat meal every week or two, make the minimal amount of changes necessary for you to stick with your diet, which must still put you in the caloric range (deficit for fat loss or surplus for weight gain) that aligns with your goals.