Vegan before 6?

That might just be because most snack and meal foods for those meal times, tend to be lactose based or high in fat. I would say, get to know your body and what foods you life and gear your diet more towards it working with your daily plan of things you will be doing. Your diet is only meant really to feed your body for the day. When I think about what I am eating, I try to notice calories somewhat, because high calories on a small amount of food usually denotes that it is processed. BUT, mainly I try to eat what I think will provide me with what I need. Energy, protein, carbs, fiber, iron, sugar, (deliciousness , and anything extra. I also try to eat something relatively high in protein after I work out to help my muscles/ drink about 1000mL (2 16.9 oz bottles) of water while I work out, and try not to go over my sugar. Sugar is a necessity but it makes your body work hard to digest it and unless you are relatively active daily, it will slow down your metabolism greatly to eat more then about 30g a day.
Your body is just a biological machine, is how I look at it. We work together. Exploring diets is helpful when you are looking at it in terms of getting to know your body. To both make it serve you, and to maintain it well. Also, anything without a high amount of processing because they tend to use chemicals that are not labeled because they are not technically "ingredients" but they add complex molecules to what you eat that are harder for your body to break down. Slows metabolism, isn't giving you the nutrient you need and so on. GMO foods are okay as long as you are comfortable with it, and anything that is inriched, I would stick to organic or kosher so that you can put faith in the preparation methods.
Red meat once week and with high fiber foods so that they fiber/grain breaks down and can help to cleans your body (on the way out)
Green vegetables have a lot of healthy enzymes that make protein that tend to bond to cancer causing agents and can reduce your risk of mutagenic cell reactions over time (which are cancer precursors)
Dark fruits have antioxidants but more importantly they tend to be high in essential minerals for cell health and maintenance like Magnesium/Iron/Potassium, things like that. Things like ginger and garlic also because they clean the blood and it helps your kidneys and they are good for your heart. If I can recommend a book that was nearly the beginning of my interests (I am pursuing a degree in a related field) It is called "The Vegetarians Cook Book" by Pat Crock. It is set up to identify the individual systems of the body and what you can eat to encourage the best out of them (health and performance) and also is sectioned out by ingredient, offering a decent amount of information about basic plants/meats/herbs/legumes/grains and so on. There are recipes, but they are not the heart of the book.
Just passing on what I have learned in the hopes to help whoever. Doctors don't approach health from the diet first when what you eat directly fuels your body or either sucks it dry. No machine with the wrong fuel will run right.

Also, check out the Physicians Committee for Responsible Medicine for information. They also do a 21 day vegan program to get people to experience what its like to go off of animal products. Thats what got me started and I've stuck with it. I wouldn't go back for anything. They offer recipes, nutrition info, medical info, celebrity encouragement, menu plans, and so much more. (I think its really cool to get recipes and encouragement from people like Alicia Silverstone or John Sally. Not just because I'm a fan, but because they are so down to earth)

Just make sure you are going into it with an open mind. Veganism is extremely beneficial when done correctly. I think there are many people diving in trying to lose weight like its the latest fad diet. If you are just cutting out meat and dairy for two meals a day thats really just an old fashioned meal plan. It wasn't untill after WW2 that meat became a staple at every meal. For any diet to work forever, you have to stick with it forever. If you can't see yourself giving up honey, veganism probably isn't for you. Maybe just strict vegetarianism as the Maid pointed out is a better route for you.

Good luck!

Have you read Food Matters by Mark Bittman? If not, I recommend you check it out. This is his exact philosophy (probably where your friend got it from.) He has lots of good reasons for doing it -- some of them are health related but many are also planet/environment/animal related -- but he claims it also helped him lose 35 lbs. Personally, I think any 'diet' where you go vegan about 70% of the time will have the same benefits -- so you could do vegan during the week, not on the weekends, vegan for three weeks of the month and not the other, etc. Or keep it more casual and just start incorporating one vegan meal into your day.