If you were a "good" vegan, as you mentioned, I cannot imagine what kind of foods you ate to have more calories compared to fat (calorie) rich foods like fish, mussels or meat.
500 grams of raw beans is 2000kcal (very little for an avg 45 year old man), contains about 120g of protein, but is around 1.5kg of beanwater sludge when cooked. Impossible to eat in a day for most people. Adding rice, pasta, or other sources of calories still does not help a lot. It takes a lot of food to get to 2500-3000kcal.
Many vegans lack calories in their diet. Older and sedentary vegans that are starting to develop protein resistance (due to age or sedentary lifestyle) also consume way too little protein. A perfect recipe for various metabolic issues and aging related diseases.