Hello FlyKid; kewl name. It's great when 18 year olds want to care about their health and 5'9" at 176 pounds means you can get in shape in a matter of weeks. My 18 year old twins are 6'4" and 6'1" and weigh around 200 pounds each. They're fraternal twins in case you're wondering why the different heights (lol).
K, so first things first. How many calories should an 18 year old who's 5'9" and weighs 176 eat every day just to maintain? Depends how much activity your involved in, but let's say you walk for no more than 2 hours per day (light activity). Then you'd need approximately 3590 calories per day to maintain the 176 weight.
To lose weight, you can subtract 590 calories per day from your diet and exercise enough to burn 410 calories per day and then you're at a 1000 deficit. We need to be at a 3500 deficit to lose one pound. If you're at a 1000 deficit per day, you could conceivably lose two pounds per week with this equation.
Now the harder part...and I say this because I never, never thought I'd be a person who counts calories...but if we want to lose weight in a healthy way, in a lasting way, it is wise to know how much we're eating. How much energy we're putting in, and how much energy we're putting out. Because that's all calories are...is energy.
I highly recommend to help you count calories of the things you are eating. And I know this might seem weird for an 18 year old, but you can take it or leave it, but you might sit down at the beginning of the week and think, what am I going to eat for breakfast, lunch and supper and 2-3 snacks per day for the entire next week? Write all the food down, make sure you've got portions that match your 3000 calorie days and go grocery shopping (might bring mom or dad). Then you make sure you log into fitday.com every day to monitor what energy you're putting in. You will learn a lot about nutrition if you read a book or two. Wanna know what's healthy? Most of the stuff on the outside aisles in a grocery store, vegetables, fruit, meat, chicken, fish, whole wheat breads & pasta, walnuts, tuna, oatmeal porridge, Raisin Bran. Make sure at least 30% of your diet is protein, super important.
Next, figure out how you plan to burn 410 calories per day. Gonna walk? Ride a bike? Go to the gym? Doesn't matter what it is. Once you lose say even 6 pounds, you can enter your weight into to find out how much less calories you might eat, or you can intensify your exercise.
2 months to graduation? You can seriously take off your shirt and look like a god by then, if you want. Remember, no matter how much tummy crunches or chest exercises you do, it's mostly about losing the fat, because underneath the fat, your beautiful muscles are lying in wait. They are there...just need to lose the fat. Don't go silly low on calories, especially since you are 18 years old and still growing. If you cut out eating after supper, and cut out junk food...and walk around the block 8 times per day, you would lose weight, simply because you've got that lovely youth growth hormone still releasing from your lovely brain.
Good luck FlyKid...you can succeed! You just have to want it bad enough.