What Is Realistic Diet For A 20 Year Old?

Realistically, when I was 20 years old, all I had to do is skip a meal and a snack, and WAM!.....3 pounds gone. Nowadays, if I want lose a couple of pounds, dieting alone doesn't help. I need to exercise. So for you, it depends on how much weight you want to lose. Cutting out carbohydrates helps, for one. Honestly, I think the best diet is to simply eat smaller portions of your regular meals and spread them out to 4 or 5 meals per day rather than 2 or 3. Cut out all snacks and junk, eats lots of vegetables. Most green veggies are literal calorie burners. Drink lots of water or low calorie drinks rather than soda and high calorie fruit juices. You'd be amazed at the extra calories you tac on by drinking sugary drinks. When I force myself to stick to a "diet" it just never works. Whenever I feel I need to lose a couple of pounds, this plus a little exercise always does the trick. Eat pretty much what you want, but COUNT CALORIES. This was very effective for me after I had a child and wanted to lose the baby fat. I never went over what my daily calorie intake was supposed to be. I lost 15 lbs quite rapidly. (with exercise of course:o)

Your age is not going to have much to do with your diet...

What is more likely to have an affect on what diet you go on are what your preferences are.

There are so many different diets out there.

However, the best thing to do is to first find out your maintenance calories:

Your body requires a certain amount of calories to maintain it's current
weight (body weight in lbs x 15)...so if you were 150 pounds, that would be
150x15 = 2,250 calories/day.

To lose 1 pound you need to be in a deficit of 3,500 calories.  So if
you ate 500 calories less than this 2,250 each day (1,750 cals/day) you would
lose 1 pound each week.

Couple that with 1 hour of cardio each day (500 calories burned/h on
average)..you'll burn another 1 pound a week.

Don't dip below 1,200 calories/day as a woman or 1,500 calories/day as a man and you should be fine...being at these daily intakes will of course result in even more weight loss each week.

As far as what you should be eating, it's a good idea to fill yourself up on low calorie foods such as veggies, lean meats and fruits.

Aside from that, here are a  few other things to add to your diet:

-nuts, oatmeal, brown rice, yogurt, no fat cottage cheese

Really, whatever helps you adhere to your diet, you should include, but minimize processed foods.

You can go out and drink with your friends or eat junk food once a week, just make sure you keep track of what you're putting in your body, don't undo a whole week's worth of work.

You can find more detailed info on setting this all up here.