200 lbs by September is easy. 200 lbs for the rest of your life might be hard, but easily doable if you find the right technique for yourself.
One major thing is the psychological aspect of it. In the science of habit, bad habits never fully go away. You can engineer methods to mitigate the bad habit but one major thing to understand and accept is that it will never cease to exist. Part of the reason why weight loss doesn’t last. So while you might eat junk food, the best thing you can do is to keep it as a treat. It’s no longer a treat if it’s frequent. Then it actually is a part of your diet. Best thing you can do is to just track it. Go on ahead and eat to your hearts desire, but track it. Then see what happens with your body. Correlate it with the amount of sugary junk food, then realize where you are, where you want to be and what you must do. The answer is easy. Cut down on the treats. The best thing is then you get to realize how many treats you can have and still achieve your objectives.
Another rule or little game that makes things interesting is to use a blood glucose monitor. Using it to assess your commonly consumed meals. Understanding how good, or bad, or when you’re more capable of handling a carb load is very useful in keeping weight down. Not doing a workout today? Try to avoid wolfing down that small baby sized burrito that blows your blood sugar levels over 200 for 2+ hours. Go for something healthy fatty, a bit of protein and satiating instead. Something of the sort can really keep that post meal blood glucose below 180ish mg/dl.
If you’ve been at your body fat % for a significant portion of your life and/or have a history of type 2 diabetes, that would be a concern. To an extent it’s a part of aging but adipose tissue is one of the biggest risk factors. You can minimize fat for your health and it can pay dividends for decades later on.
This is just an intro.