Some people live vicariously through their pets. I've seen 35 lb/ 16 kg cats barely able to move or breathe with equally overweight owners who claim they cannot 'say no'. You wouldn't believe the number of birds I've seen critically ill or dying because their human can no more put the bird on a good diet than they can put themselves on.
How about changing things? It's actually easier to feed a bird the right things and it's possible you can pick up a few better habits yourself.
When I began to pursue an avian speciality certification after establishing an animal care organization, the subject of nutrition simply fascinated me. So much information is flooding the net these days about what to feed a companion bird, whether a budgie/parakeet, cockatiel or marvelous macaw, it's sometimes difficult to wade through the junk science, old wives tales, well meaning owner advice or just plain dangerous suggestions.
On the top of my list of things to NOT feed any bird with a hooked bill (parrots from budgies/parakeets to the biggest macaws) would be vitamins from pet stores. I really wish they weren't allowed to sell them (along with the supposed antibiotics or sprays or mite protectors). Another top item would be grit. If your bird has a hooked bill, it does not need grit, never did and never will. One of the most frequent causes of crop impaction in psittacines is from foreign objects, which grit is to them. They leave the seed shells behind when they eat, so there's no necessity for a tool to break the seed open in their gut, like pigeons and canaries, finches and so on would need. So when you're looking through the products in your local pet shop, don't be taken in by slick packaging that might have a picture of your bird on it. Put nothing in your bird's water and keep the sand (grit) out of their mouths.
We all know not to feed our feathered friends alcohol, caffeine, chocolate and avocado, but did you know how many foods have those things in it that we might not suspect? I've found some of my clients feeding their bird regular treats of power or health bars, thinking it must be good. In some cases these birds were getting chocolate chips the owner didn't realize were tucked inside.
Keep in mind that just because a food is green, doesn't mean it's healthy or safe. Though most are probably just food coloring and others are spinach based, some are made from avocado, so read the ingredients carefully. I'd also like to clear up the great avocado scare too. No, this isn't the best fruit for a bird, but chances are a bite isn't going to produce an emergency. The larger the bird and the further away from the pit, the less likely there will be any harm, but I want to stress - this is something you should NOT feed your bird.
And don't use avocado branches for perches.
There is also a big difference in what some owners think is a "little bit". One fellow gave his companion a piece of cookie regularly. I never considered how big that "piece" might have been until making an in-home visit and watching him offer the treat. When I saw 1/2 of a cookie going to the bird, it made a lot more sense why I was seeing signs of severe nutritional problems. Once the gentleman learned that a "little bit" from now on would mean no bigger than his thumbnail, we turned a big corner and this bird made a tremendous recovery.
It's generally recommended that most of today's companion birds have a predominantly pelleted diet. Pellets have been continually updated since being introduced to the market years ago and today's formulas are better than ever.
While birds might enjoy iceberg or head lettuce (the light green variety), celery and the like, it's mostly water and not much nutrition. Instead, go for the dark leafy vegetables, fruits and legumes. Include the colors orange, yellows , green, plus reds too! Think sweet potatoes/yams, squash, melons, oranges, peas, chard, beets and others.
Brown rice, quinoa (pronounced 'keen'wah'), whole wheat couscous and natural, whole grain pastas are great choices too.
Birds do not tolerate animal fats well. Good fats are most plant fats like soy, olive and canola oils. No fried anything
A good feeding supplement is all natural, human baby food (stick to the orange colors), but make sure to read those ingredient lists.
Birds should not have any added salt/sodium and even we humans should avoid foods that list 'sulfites' on the ingredient list.
Let them enjoy cooked pasta or rice, whole grain bread or toast - NOT packaged foods which are exceptionally high in sugars, salts and chemical additives.
Here are some great sites for feeding advice that is applicable to all hook bills from budgies/parakeets to conures, greys and macaws
http://www.cockatiels.org/articles/nutrition/diet.ht ml
http://www.letstalkbirds.com/cockatiels.htm
The Bird Care Library at Harmony Animal Hospital http://www.petvets.com/petcare/birds.html#nutrition
For some recipes to make that both humans and birds can enjoy, check the bottom of this page www.4AnimalCare/birds
So keep in mind that for all not to feed your bird, there needs to be a good choice about what to feed them. Who knows, you might end up eating better yourself!