I'm not vege or vegan, but my missus is. So that means I am most of the time.
I'm 46 and I weigh less than 140 pounds (Especially after a long run on a hot day. ;-). I'm running 70 miles a week (working up to 90+ on the way to Boston). I'm in the "not slow, but certainly not elite" masters category. My calorie requirements seem to be ~3000-4000 a day. Most of that information is for comparison: it's genetic, for the most part; not a by-product of diet or running or anything else.
I do very little breads, zero pastas, and no milk. A bit of cheese with wine and a bit of ice-cream is about it for dairy for me.
Staples are eggs, beans, sweet potatoes, broccoli, asparagus, kale, spinach, bokchoi, potatoes, carrots, oranges, apples, bananas, and some grains like buckwheat and rice - mostly in "vegan protein powder" versus any other way. Used to do quinoa and rice, but didn't get enough benefit from them versus the grain-factor issues; and I like the legumes and tubers stuff better.
Breakfast is always 2-3 eggs plus sauteed vegetables. Easy alternative is a big fritatta (or little ones in cupcake pans), then eat it for a week. Gets all the veges stirred in and makes it fast and easy.
Lunch for me is often "out" because I like the time alone. Indian is the only reliable quality vegetarian food I've found. Thai can work, but vege is not their specialty - you have to ask the right questions, which can be uncomfortable with a language barrier.
Dinner out is Indian or Thai. At home, it's various soups - mixed beans, lentils, chili, etc. Lots of tasty options that are "make a big batch and eat for a week" stuff.
I keep Kind or other bars around all the time for mid-meal snacks. I stick to raw vegan bars and avoid the sugary chocolate stuff.
I also do about a gallon a day of blended fruits and veges, kale and vegan protein powder. Blended every morning, then take it with me in 32oz jars for after / in-between meals. This adds about another 1000 calories and ~120+ grams of protein.
Without the last two, I get light-headed a bit. I run a crazy-high metabolism of these types of foods. With the bars and protein / food shakes, I keep solid energy all day.
FTR, I will also eat meat for lunch or dinner - ideally fish, but also some chicken or pork if that's what's around. As I said, I am not vege or vegan; but I've spent many days without any meat and I feel just as good - typically a little better energy - without the meat as with it. I'm just too lazy to do it all the time.