The majority of people who lose a lot of weight will regain it eventually, and I think it's because they fail to create, and sustain, a lifestyle that doesn't cause obesity. If you want to look like an athlete, you have to live like one. The absolute masters of augmenting body composition are professional bodybuilders; look into how they deal with nutrition, and then restructure your life around athleticism.

Learn to maintain your weight first (unless you're medically fucked) and learn to lift. Then, start a 25% calorie deficit. Once you start to lean out, start aiming to lose 1% of your bodyweight per week and sprint to the finish. Tools like metabolic equivalent of task (MET) are useful to leverage if you're active. TDEE calorie values account for ~5000 steps per day, so don't count step calories unless you're going well past that.

Get 0.8 g/lb of protein, 33% of your calories from fat, and the rest from quality fibrous carbs.