You can lose weight just by changing your food intake but most likely not from JUST exercising.
If you’re just starting out, I would say begin with a healthy eating plan and further down the line, incorporate exercise. It will help with toning, muscle building and being in a great mood.
Just remember to introduce exercise in moderation, meaning, don’t suddenly try to commit to 6 days of 3 hour intense workouts. Start with less days and shorter workouts then add more as you get stronger and more committed.