Its almost 100% certain - if your vegan diet looks exactly like a standard American diet (using substitutes) - you will gain weight unless you're meticulous about counting calories.

If you want to be healthy on a vegan - do not eat vegan junk food. Being healthy on a vegan diet means eating whole foods - minimally processed. The food you eat should be high in fiber, low in fat, and high in water content. Most of your calories should come from minimally processed starches.

The incomplete protein thing is a myth.

https://www.forksoverknives.com/the-latest/the-myth-of-compl... Frances Moore Lappé retracted her statement about incomplete protein.

These articles are essentially Vegan FUD - hoping to get you to worry about health minutia. It tries to poison the well essentially. A whole food plant based diet is a great way to maintain your health.

https://nutritionfacts.org/video/uprooting-the-leading-cause...