i'm about 6'0 and 170 pounds and I really desperately want to lose 15. I have been exercising a LOT (2 hours of cardio every day) and cutting down to 1500 calories. Though i have seen differences in some parts of my body (my legs and arms appear more toned) i have gained 2 pounds in 3 weeks and my stomach will NOT go away. I don't know what to do. I also do ab exercises. should i be eating something in particular? i would do almost anything to make my stomach go away.
While ab exercises will make those muscles stronger, they will not "spot reduce" the fat there. Fat is gained or lost in genetically determined patterns, so you may just have to lose more body fat in general (burn up more calories than you eat).
You may want to consider using body fat percentage as a means of tracking your state, since weight includes both muscle and fat, and exercising can increase muscle (which is healthy, even though it makes you heavier). Note that your current weight is well within the usual "healthy" weight range, though it is still possible to have too much (or too little) body fat.
For weight training, you did not mention doing much in the way of big muscle exercises. Working the bigger muscles may help them grow, increasing your metabolism more to burn more calories even at rest. The bigger muscles include chest (pushups, bench press, dips), back (pullups, rows), and upper legs (squats, lunges, etc.).
As far as eating goes, you did not describe what you eat currently, but you probably know what kinds of foods to eat (vegetables, whole fruit, beans, whole grains, fish, lean meat, skim dairy) and what to avoid (most processed and packaged foods, sugary drinks, foods high in both fat and carbohydrate).
What kind of cardio exercise are you doing? If it's very vigorous, then you likely need to cut back some. You might be burning too many calories compared to the amount you eat per day and thus, your body isn't dropping the pounds since your metabolism can slow down from doing this. Now, if it's 2 hours of walking or gentle cycling, this is usually okay.
You might want to swap out some of that cardio time for strength training. A combination of both cardio and strength training will give you the best results for weight loss and getting fit and toned. Keep up with your ab exercises, as well as your other exercises.
What kinds of food are you currently eating? You can cut back on calories, but not eating the right foods can cause you to have fat around your stomach area. I find that cutting back on overly processed carbs helps big time! I used to eat way too many carbs and processed foods. Now I try to have a lot of fresh fruits and vegetables and lean meats. I only have small portions of breads and rices and try to not eat the white ones too often. I also avoid too much sugar, other than fruit. There are a LOT of low calorie, diet foods that really aren't that nutritious. They're just low in calories because the portion is small. I cut out a lot of these foods when I was losing weight and it helped a lot.
Your body may need more than 1500 calories. I am only 5'4 and had to eat in the 1200-1500 range to lose weight, so 1500 sounds low for a person of 6', especially with your level of activity. I also found it helpful to only do cardio exercises that are very challenging, for less time. I would keep my heart rate up in the "cardio" range, not the "weight loss" range and got way better results. It is tough, but I now enjoy a good challenge!
Lastly, your weight loss may just be slow. It's possible the weight gain is from muscle weight or you might even be holding in water weight if you happen to eat a lot of sodium (like from canned or frozen dishes, soups, etc). I know a lot of people who took about a month or so before they started losing weight. Maybe this is happening to you!