What is the best chatgpt/GPT4 command to use to extract only all messages in a topic while removing out all the header/separator information?
Eg at https://www.rapamycin.news/t/what-are-your-favorite-low-er-calorie-low-calorie-per-volume-ratio-or-appetite-suppressing-foods/3625
Aside from using the API to interact with ChatGPT and the content of your topics and replies, you can also feed it the raw markdown, which is easier to copy and paste at least. 
In Discourse, use the raw route with the topic ID, like so: https://www.rapamycin.news/raw/3625/
That greatly reduced the amount of meta data and rendering information included in the content. 