NUTRITION

A budgie's metabolism works really fast and the bird could die if it doesn't feed for 24 hours.
A parakeet's basic diet consists of seed mix, veggies and water. Budgies require fresh water each day. You can also make them a drink of Gatorade and water(1:1), but make sure there is still plain fresh water available at the same time.
Veggies you can give your bird:
*Lettuce (avoid Iceberg lettuce, because it doesn't have any nutritional value)
*Carrot (grated or whole)
*All kinds of fruits (banana, strawberry, apple, mango...)
*Broccoli, celery, parsley

From time to time you want to sprinkle some vitamins over your budgie's seed mixture or fresh food. Don't put the vitamins in the water - it will only encourage bacterial growth! Other things you can give your budgie:
Cooked pasta, hard cooked crumbled egg (with shell), grated cheese, cottage cheese, whole grain breads, sterilized sand or grit once a month.

There is a wide selection of budgie treats available in pet stores. I like to have a treat stick hanging in my bird's cage all the time (although it's not necessary).
The thing budgies really love is millet spray. In fact, you can give it instead of a treat stick. Two inches of spray per day per bird is enough. By letting them eat more you'll have overweight birds pretty soon.

Dietary essentials and natural sources

Protein- meat, soybeans, eggs, dairy products
Fat - butter, milk, oils, oil seeds, cream
Carbohydrates - canary and millet seeds, honey, veggies, cereals
Vitamin A - peas, beans, eggs, milk, asparagus, veggies
Vitamin D - eggs, fish liver oils, fortified milk
Thiamine - whole grains, veggies, legumes, muscle meat, eggs, yeast, milk
Niacin - milk, lean meat, yeast, liver
Riboflavin - egg yolk, milk, wheat germ, yeast, chicken, beef, green leaves, liver, cotton seed meal
Ascorbic Acid - citrus fruits, raw cabbage, tomatoes
Iron, Calcium, Phosphorus - milk, eggs, oatmeal, soybeans, veggies, liver, green-ground bonemeal, bone marrow

Foods to avoid:
Rhubarb, avocado, alcohol, chocolate, coffee and cola - they're all poisonous and could kill your bird!