crunches

First of all, losing 20-30 lbs in the next month is NOT a realistic goal. You could aim for 10lbs, 15 AT MOST. But it will take ALOT of self restraint and hard work. Doing crunches and sit ups doesnt necessarily make u lose belly fat but instead it makes ur abdominal muscles stronger and fat feeds muscle. So the more muscle you have the more fat you will burn during work out! As for losing the weight, definately doing an hour or more of high intensity cardio a each day will get you close to where you want to be, as well as adding in 30 minutes of some sort of resistance training- lifting light weights. Its not so much the weight but the number of reps that you do, so aim for a moderate weight and high reps. Also really watch what you eat. Cut out any and ALL unnecessary fats- mayo, salad dressing... you name it... stick to meat, low fat dairy and anything from the earth- veggies, fruit etc. You will also find a benefit in eliminating all fluids except for water! Sodas and such that have carbonation will make you bloated, as well as are loaded with sodium which cause you to retain water! If you find yourself hungry throughout the day drink a tall glass of cold icewater before eating food, as 85% of the time that you think you are hungry, your body is actually just dehyrated and thirsty! Good luck!