Question: I'm vegan and in general I don't have any problem maintaining my weight, but for the last few months I've wanted to increase my weight and it's been really hard. 

Could others who have had the same problem give me some tips or advice on how to gain weight on a vegan diet?

Answer: 
My **#1** tip: **drink calories**

If I want to gain weight, I make a smoothie with two bananas, a generous scoop of nut butter, vegan milk, and a tablespoon of carob. I drink this alongside my normal breakfast. I typically gain about 4kg per month doing this.

Turning food into drink by way of smoothies should enable you to eat more calorie-dense food easily.
If you want to gain lean weight - instead of a mix between lean weight and fat -, then you need a high protein diet. Researchers don't seem to agree on exact numbers, but, for adults undergoing regular weight training, [most aim at higher than 1g/lb of bodyweight](http://www.bodybuilding.com/fun/maki1.htm) (2.2g/kg for those under the metric system). 

So, not only you need to ingest more calories than your TDEE ([estimate yours here](https://www.supertracker.usda.gov/bwp/index.html)) to keep on gaining weight, but you also need to keep a high protein ratio, as well.

The best sources for piling up protein in a vegan diet are soy protein (usually 20-24g of protein per 30 grams), wheat gluten (70-75g per 100 grams) and spirulina algae (arguably 10-20g per 30 grams). Other sources might include peanut butter, other nuts and beans, but bear in mind most of those sources have low protein ratios. 

Of course, changes in your diet should be discussed with your dietitian. Exercise is also an important factor, since high protein diets have been proven not to provide additional benefits for sedentary adults.