No, it's not appropriate. Everyone's sexual experiences, regardless of their body type or sexual orientation, are private matters. Publicly sharing a'sex story' violates privacy and can also be considered vulgar and disrespectful in most social settings.
Mainstream literature values things like character development, plot, and themes that are relevant to a broad audience. Fanfiction with inappropriate sexual content in a kitchen or any such setting has no place in it as it doesn't meet the criteria of what is considered appropriate and valuable in the world of mainstream literature.
One way is to have a story about a community kitchen event. People of all ages are coming together to cook and share food. There are hugs of greeting, shared stories, and a general sense of togetherness. This gives the idea of a lively, energetic environment in the kitchen which can be related to the idea of'sex in the kitchen' in a family - friendly and positive way.
We should avoid discussing sexual content. Instead, we can talk about topics like body positivity for plus - size women in a general and respectful way.
There are many other interesting and positive topics to discuss, such as healthy lifestyles for fat couples or their relationship building in non - sexual aspects.