Well I think the first step to fixing the problem of these 30lbs is to figure out where they came from. How has your lifestyle changed since highschool? Are you eating out more often? Are you less physically active because you're studying or hanging out? Drinking and partying? Are you stressed constantly?
All of those can affect weight gain. If you find that you're not preparing your own meals then your diet won't be as nutritious and you'll find your portions are much larger than they should be. Take an hour each day to figure out and prepare some of the food for the next day. If you live in a dorm, strike a deal with your roommates and trade off cooking dinner; not only will that free up time on some days but you'll be able to slow down, socialize, and be able to relax during a meal. Try looking into Ensure drinks or meal replacement bars; while I don't recommend you replace every meal with them, they can make a quick mid morning/afternoon snack so you don't overeat at lunch/dinner. Also make eating breakfast a habit. Breakfast doesn't have to be an ordeal, a poached egg, piece of toast, an orange, and a glass of non-fat milk takes about 10 mins to prepare, or you could hard boil your egg the night before and save even more time than poaching it. Needless to say that fruits, veggies, whole grains, low fat dairy, and lean meats should be the majority of your diet. Fast food, sodas, candy, and white flour products (white bread, white buns, crackers) should be avoided or enjoyed sparingly. It's not as restrictive as you would think, for instance instead of reaching for chips to snack on, go for air-popped popcorn (popcorn is a whole grain). A 3 cup serving of air-popped popcorn has 90 calories and 3 grams of fiber. Make sure you're drinking enough water, as it helps fat burning for a number of physiological reasons, 1/2 oz for every pound of weight every day, slightly more if you sweat a lot during exercise.
As far as working out, there are many options here too. Walking and jogging are great exercises to get you burning calories. Try riding your bike around on the weekends instead of using your car. Calisthenics like situps, pushups, pullups, squats, lunges, etc. are also good resistance exercises that can be done without the use of weights, although I do recommend investing in a basic dumbbell set eventually. Resistance training, synonymous with weight training, is very important. As you diet the closer you get to a healthier weight the more your body will shift to burning some muscle along with fat. Resistance training minimizes this effect. If you're afraid of bulking up from pumping weights, have no fear because you can't readily gain muscle mass while in a dieting phase even though you might experience a decent gain in strength. Women also don't have the hormone profile to bulk up to the extent of a male bodybuilder, or most women anyways.
You should realize that a pound of fat is 3500 calories. To burn two pounds of fat a week, the recommended healthy pace for weight loss although more obese people can lose more, That means 7000 calories, or 1000 calories a day. Well how the heck are you going to do that? The easiest way is to cut out 500 calories from your daily intake to maintain your weight, and to burn 500 calories during a workout. To get a idea of your caloric needs to maintain your weight use this page Once you get your BMR then follow the link below the calculator to the Harris-Benedict equation. Multiply your BMR by the multiplier that best describes your current lifestlye, exercise included. Lets say for example you do that and come out with 2300 calories. If you subtract 500 from that and consume 1800 calories a day and work out with moderate intensity 6-7 days a week, then you're well on your way to two pounds a week.
Chronic stress can also add to your weight gain, it's a built in survival factor. To reduce stress try some breathing or other relaxation exercises, enjoy a cup of unsweetened green tea, or take a long bath or a dip in a jacuzzi.
As far as supplements, many of us around here recommend a standard multivitamin and a fish oil supplement. Fish oil contains omega-3 fatty acids which have numerous health benefits, chiefly raising good cholesterol and lowering the bad, and supporting the body's processes that help you lose and maintain a healthy weight. Diet pills or gimmick products aren't needed.
I hope that helps to get you started, feel free to ask specific questions.
