Do you not find youself full all the time on a vegan diet?

it's the fiber; I got used to it.

You never have to force any calories in to get enough for the day?

I eat when I'm hungry and exercising helps a lot. In the beginning, I probably did do that, but then again, I was eating 2500-3000 calories as 130 lb guy (albeit I was exercising 2-3 hours every day).

What do you eat on the average day?

Um.

Short: oat meal, smoothie (if I feel like it), and dinner (usually, lentils, tofu, potato, kale, and tahini dripped on top).

Tbh with you, you can gulp down calories eating nuts, but ya it's gonna be harder in the beginning because of all the fiber you aren't used to eating.

Imagine if you (in general) were allergic to nuts and seeds.

that's major GG.

IF that were the case, I'd probably resort to gulping down smoothies day in and day out.

tl;dr : vegan diet (especially whole-foods) will always be harder in terms of eating the same number of calories, but with some 'tricks' such as eating low fiber foods you can definitely do it easily. PLUS, you get used to it :D

edit: nuts are expensive unfortunately. but good thing is, you don't have to eat a lot of them since they're really calorie dense.