Carbs are sugar, that much is true. No one said it's the same as soda or processed sugar, though, so that's needlessly preemptive.
I eat a lot of potatoes, beans and (forbidden; no more white) rice. And I love split peas, lentils, and all kinds of legumes and nuts. But the only vegan things that have a lot of calories are avocados and nuts. I eat them all the time, but it's simply not enough.
I can make potato soup and lentil and cauliflower soup, and bam, I'm hungry again two hours later.
I love a lot of vegan cuisine and regularly consume it. I aspire to become a vegetarian and, maybe, a vegan one day, strictly for spiritual/religious/moral reasons (the carbon imprint from meat eating is 3-4x the carbon imprint from transportation), but it will take time.