How do you know what advice to follow?

Regular soda is better than diet soda because of the aspartame.  Eat whole wheat bread not white bread.  Wheat and gluten are making you fat.  Eat eggs, don't eat eggs.... Just how do you know what advice to follow?

Today it is so hard to decipher diet advice.  Just how do I know what to eat?  I just read a couple of articles that are saying that wheat could be contributing to your weight gain or making it hard to loose.  This comes after having "Eat wheat not white" drilled into our heads.  Other articles are stating that if you are going to drink soda that regular soda is better than diet. The best option I believe is to leave it out completely but everyone slips up once in a while so how do you know which one to choose?
Do you ever get the attitude "Its all going to kill me at some point"?  If it is great today in 3 years its going to be bad for you.  I have become a believer in the above statement to some point.  We all know the end result its just the journey that we can adjust.  No I don't mean that if you like candy bars  to eat them everyday it doesn't matter anyway.  I am leaning more towards the idea of  "All things are good in moderation" or "Moderation is key".  If I eat a cheeseburger and fries everyday it is highly likely that I will endure some health problems.  If I indulge once every couple of months its not the end of the world.  The key is not to "slip up" one right after the other and to get a good description of "moderation".  If you have acknowledged nutrition at all you have a pretty general sense of what is good and what is not so good.  The trick is portion control and being honest with yourself.  By being honest with yourself I mean to acknowledge what you are actually eating.  A good way to do this is to write down on a list or in a journal everything that touches your lips when it touches your lips even if it is a lick of the spoon!  If you have never done this you may be amazed by what you see.  We tend to forget the little bits here and there and they can really add up.
So now you get the idea of moderation but are still wondering how do I know what is ok and what isn't.  If you have ever changed your eating habits even if for just a week or a couple of days you know that you feel different when you eat different.  For instance, when I fall off the wagon and eat greasy foods (easy to do when you are on the go a lot) I feel sluggish, bloated and just plain blah.  When I am watching what I eat and follow my exercise routine I feel more energetic and better about myself as a whole.  Not so sure what I am talking about?  Try it for two weeks.  For one solid week eat junk, then the next week cut out the junk and eat self prepared foods, fruits and veggies, etc.  Keep a journal about how you feel each day during the two weeks and at the end compare the two.  Now I assume the majority of people already know the difference that I am talking about so I don't encourage you to do this but if you really haven't noticed try it.  Now you know what to eat!  The way I see it is that everyone is different and what is bad for one person may be perfectly fine for the next.  If something is working for you and you truly physically, feel good then it is fine in moderation.  I say physically because sometimes a candy bar can make me feel great emotionally but that doesn't mean it is ok for regular consumption.
Another suggestion is to eat less processed food.  When you read labels look at the ingredients...Can you pronounce everything on the list? The more ingredients that are listed on the label is a good sign that it is not the best thing to eat. Another way to think is that most likely if you are reading the label it is processed.  Not many fresh foods have a label.  We live in a processed society it is hard to convert to a no process diet but  it is not impossible to make changes.
So I guess I am saying don't get extremely caught up in the fads of what to eat and what not to eat.  There is a new improved food pyramid that is a great guide.  You can find it at www.mypyramid.gov you can also track your food intake there.  Find what makes you physically feel good and works for you.