I’m not a huge proponent of celebrity fad diets or exercise routine but Brad Pitt did get very fit during Fight Club by eating mostly lean protein/nutrient dense food and fewer/no carbs or fatty foods
It was paired with a different muscle group worked daily + heavy cardio. I’ve actually been loosely following the routine for only a few weeks and idk if I will stick with it but basically:
train a different muscle group per day, calorie deficit, protein and veggies and oats, run a lot. I feel really great so far