Is it possible to lose weight doing brain exercise?
No The amount of calories the brain consumes is basically the same whether it is doing anything or no. Best case only about 3% increase in calories consumed by the brain or about 50 calories per day, which is miniscule and most studies do not even show that much.
Additionally buring calories is only important for weight loss once consumption is controlled. It is too easy to out eat any amount of exercise.
https://www.scientificamerican.com/article/thinking-hard-calories/