First of all...you can't accomplish anything that's impossible and this goal is truly impossible. Do you have a vacation involving swimsuits or something?
Regardless... Sorry to burst your bubble, but you're not going to lose 80 pound in two months. It's not feasible and it certainly wouldn't be healthy. The absolute most you'll lose is 20-25; you'll be lucky if you hit 30.
Cut back on what you're eating; take away sodas and sugary juices and other sugary drinks. Get rid of all the fatty snack food in the house or at least get them out of your reach. Add fruits, veggies and some low calorie, low fat yogurt t to the grocery list i'm a big fan of yoplait -- 110 calories and i eat it with a banana or apple or add in some granola in the morning). Stay away from red meats and try not to go out to eat too often. Eat light for breakfast and lunch and a tad bit heavier in the evening, but no eating past 5:30. For example: my average day are as follows... I told you what i generally eat for breakfast. For lunch, i'll have a small chicken breast salad (boiled chicken) with a tablespoon of light ranch dressing. For dinner, i'll have stirfry chicken (not fried...just spray non-stick spray on a skillet, cut t he chicken breast into pieces and cook) with a dip that i make at home and then some steamed carrots and broccoli. Sometimes instead of the steamed veggies, i'll mix a half cup of brown rice with peas and cut up carrots. All of this leaves me in the 800-1000 calories in take range, with a snack of a natural fruit leather or a cup of cut up strawberries and a banana. Also, remember to drink lots of water. It will help cleanse your system as well as help you lose water weight.
They key to losing weight is burning more calories than you take in. So with my example above, i take in about 1000 calories daily; to lose weight, i need to burn more than that. Everybody naturally burns calories just by their body functioning and by them doing daily activities but to lose weight, you need to do over and above that. Exercise. I burn anywhere from 1000-2000 calories a day between my cardio and weight training, both of which i do every day. A pound equals 3500 calories so if i burn 2000 calories a day minus the 1000 calories i take in, i will have burned 1000 calories in total that day and i will have shed a little over 2 pounds by the end of the week.
Cardio gets your heart pumping quickly and for an extended amount of time so it's great for weight loss. You could go running or even just walking outside. You could use a treadmill, like most. You could go swimming, play tennis or another sport. Or at the moment, for my cardio i'm doing a kickboxing video that i found on youtube and downloaded. It's 10 minutes long, but i run through it 4 times twice a day and it really takes the calories off.
While cardio is very important to weight loss because it sheds calories quickly, weight training is also important. Using weights puts burns in your muscles and enables to burn calories for a longer period of time after you've stopped working out. Because of this, it's very important to include both cardio and strength training into your efforts to lose weight. If you don't have weights, maybe your school has a gym or small weights range from $3 - $7 at wal-mart
You won't get to where you want to get. That's just a fact. It took time for you to gain all of this weight and it'll take time for you to lose it. Just stayed determined to get what you want.