Hi,

I can only provide a basic answer… You need to eat less energy than your body will consume.

It s difficult to answer your question. If you didn’t practice any sport for a long period you need to be very progressive and take time to avoid any injuries. Find a beginner program here. You can choose an « everything » program.

I've started exercising again in june with a diet and did to much to quickly and last week I was very sleepy and lack of energy. So I practice sport but less harder this week and eat a bit more.
The point here is that you want to loose weight very very quickly and your body can’t process that in a healthy way. You’ll have to listen your body if you try to loose weight in 90 days. It’s very stress full for your body.

My advise, take your time to strengthen your body and tendons, do some cardio while eating healthier. You can find advise in the darebee book « build to last ».

Happy training !

Édit : there are meal plan here, it’s sister website of darebee.