I see from your profile that you’re female...but, I think the advice to build up your arms and legs would be the same for both guys and girls...
I don’t think you want to gain fat...just muscle...right? So, the best trick would be to build up the muscles in your thighs and upper arms....lifting weights, squats, push-ups.....
This will build you up giving you nice firm curves. You don’t mention your age...but, if you’re in your early teens then you’ve still got a lot of growing and developing ahead of you.
Get yourself on a nice diet of healthy foods...lots of fruits and veggies, lean meat/chicken/fish...whole grain bread, 2% milk, fat free yogurt....
Check out this website...it gives a lot of good information on building a strong, healthy body.
Bread, Cereal, Rice, & Pasta Group
- 1 slice of bread
- 1 ounce of ready-to-eat cereal
- 1/2 cup of cooked cereal, rice, or pasta
Vegetable Group
- 1 cup of raw leafy vegetables
- 1/2 cup of other vegetables cooked or chopped raw
- 3/4 cup of vegetable juice
Fruit Group
- 1 medium apple, banana, or orange
- 1/2 cup of chopped, cooked, or canned fruit
- 3/4 cup of fruit juice
Milk, Yogurt, & Cheese Group
- 1 cup of milk or yogurt
- 11/2 ounces of natural cheese
- 2 ounces of processed cheese (1 ounce is about the size of your thumb)
Meat, Poultry, Fish, Dry Beans, Eggs, & Nuts Group
- 2-3 ounces of cooked lean meat, poultry, or fish (3 ounces is about the size of a deck of cards)
- 1/2 cup of cooked dry beans or 1 egg counts as 1 ounce of lean meat. Two tablespoons of peanut butter or 1/3 cup of nuts counts as 1 ounce of meat.
Breads, Cereals, Rice, and Pasta
(at least 6 servings daily)
Breads: whole-grain, whole-wheat, cracked wheat, multigrain, or oatmeal. (Go easy on high-fat spreads like butter.)
Cereals: whole-grain, hot and cold.
Rice and pasta: brown rice, whole-wheat or enriched pasta. (Try tomato sauces, which are lower in calories than cream sauces.)
Fruits
(at least 2 servings daily)
All kinds: fresh, canned, or frozen.
Vegetables
(at least 3 servings daily)
All kinds: fresh, canned, frozen, boiled, steamed, or baked.
Milk, Yogurt, and Cheese
(at least 2 servings daily)
Nonfat or lowfat milk, yogurt, and cheeses. (Foods from this group contain calcium, which is very important in a growing body.)
Meat, Poultry, Fish, Dry Beans, Eggs, and Nuts
(at least 2 servings daily)
Meat, poultry, and fish: lean, skinless, broiled, roasted, or simmered instead of breaded and fried. (Or try dry beans and peas, which are lower in fat.)