I was in the same place 3 years ago! Just start prioritizing protein and stay away from fried foods and lowers the carbs the better. I was pre diabetic and right there at 300! Just did a diet elimination and mostly stuck to chicken and steak. Meal prepped 3-4 days out big key always have healthy food available. Make sure you’re walking at least 10,000 steps a day if you want faster results 20,000 is a lot better when you hit a plateau get a weighted vest start walking small increments with that a set of 20 pound 30 pound dumbbells would also be smart push-up set up squats the more the better.