If you are working out and actually want to change your body fat into body mass my boxing coach recommended this:
About 3 hours before your workout eat a portion of pasta, bread etc. basically carbohydrates. I usually eat a sandwich (nothing to fancy just plain cheese and salami) or something because of my schedule. Whatever you do, DO NOT eat to little trying to cut body fat. If you want to cut fat you will need energy, carbohydrates digest slowly, giving you more energy over time. Just try driving a car on an empty tank, basically the same with your body.
When you get home eat something with a lot of protein (none of that bs supplements, that shit is for building muscle mass and bulking up). I personally eat from 4-5 eggs about 45 minutes after training.
I'm a competitive boxer and train every day for 1h 30min of rigurous training. Diets and all that only work with a workout, you can't just diet, starve yourself and expect to stay healthy. This works great for me and have made a lot of progress. It's great for maintaning weight and replacing body fat with muscle.
Now for the workout:
In my gym we start with warming up, THIS IS VERY IMPORTANT! Many people just dive right in and don't stretch which can really hurt you in the short and long term.
We usually start with weights, depending on what you want: -swole: Heavy weights, which you can barely lift up to max 8-10 times
-ripped: Medium weights, which you lift as fast as you can from 20-25 times
When lifting weights it's very important not to overestimate your strenght, start small and find your limit (trust me, it will save you a lot of hurting)
Then cardio, cardio is very important in everyday life. Not a lot to explain, run. And if you have flat feet here's a YouTube tutorial on how to fix them: https://www.youtube.com/watch?v=u45qdEm_nOM (Also let's you know of you have flat feet, if squating and dead lifting feet are very important and you don't want to take any chances)
Finally stretch to reduce muscle cramps and get some vitamin pills with magnesium, magnesium plays an important part of reducing muscle spazms and cramps.
After your workout your muscles will need to regenerate faster therefore eat something sweet. I usually eat a banana. A piece of candy or two is not recommended but if you have no other option it's better than nothing. You don't want to starve your body because if you don't feed your body it will need to take nutrients from your muscles rather than from your fat or food that you eat.
This is pretty detailed and I hope I helped in any way shape or form. Also don't eat ANY fast food, that shit messes you up. If you have any questions feel free to ask me.