Okay ... I'm going to try and reply without blowing my top and lashing out at you ... even though I REALLY feel like it

'Deep Breath'.
Right. So, you heard and read a 'bit' about this thing called clen. Then you read a bit about using it with T3. Have you researched what the ACTUAL effect of these substances are on your body and how it could go REALLY TITSUP and screw you and leave with a busted thyroid for life ... ? Probably not, eh? Well, at least you had the common sense to register on here and ask about it before using it (I hope you haven't started messing about with it yet?) You are 21, 5'10" and wiehg 245lbs. You admit that you are fat. That's also a very good thing. Now, you are looking for a quick and easy way to get your partial obesity under control and slim down, but the quick and easy way will only work while you use it now and then it will stop working and you'll be back where you are now (if not worse off) within a few months after.
No.1 - Get your diet in check. Go to the link below and research there, create a post there asking for guidance.
Diet & Bodybuilding - EliteFitness.com Bodybuilding Forums
No.2 - Once your diet is in check, you need to get a proper training routine squared away ... you'll get advice on that in the same link above.
No.3 - stick to your new diet and training routine for at least another year and reap the rewards of healthy living ... that's what Sizzle meant by lifestyle change, and like most of us on here, she REALLY knows what it entails ... eating clean and training regularly will become a lifestyle for you and not just something you do on occassion to bullshit yourself into thinking that you are at least trying and then kick it for months and then try again only to never see any difference and become demotivated. If you are serious, you will MAKE time to prepare the foods you require and you will MAKE time to train, because you are serious about your health and, consequently, how long you will have your life to live.
Once you have become accustomed to your NEW and IMPROVED lifestyle, you'll start noticing the excess fat melt away without messing up your body's hormonal system. Go see a GP and ask to have a full blood panel done by a lab. Post those results on this forum in the link I provided you with and the people in there will assist you in working out a diet around those figures. You can easily get down to a much healthier 220lbs in a year if you are TRULY commited. From there, you can have your %BodyFat measured and see where you are at. If you are around 15% - no more than 17% we can start looking at using exogenous components in assisting you reaching an even more leaned out and toned physique. You would still not be advised to run Clen and T3 at that stage, because it is dangerous and you wouldn't need it then either.
Please, I angrily ask of you nicely (oxymoron, I know

) to take all this advice to heart and follow it to the letter, otherwise you are going to suffer the consequences for the rest of your life.