The caption read: 'You guys… @flattummyco just dropped a new product. They're Appetite Suppressant Lollipops and they're literally unreal.
'They're giving the first 500 people on their website 15% OFF so if you want to get your hands on some… you need to do it quick! #suckit'
However the advertisement immediately came under fire from followers - with The Good place star Jameela Jamil leading the complaints.
Addressing Kim directly, she wrote fiercely on Twitter: 'No. F*** off. No. You terrible and toxic influence on young girls.
'I admire their mother's branding capabilities, she is an exploitative but innovative genius, however this family makes me feel actual despair over what women are reduced to.'
Her sentiment was echoed by many - with one commenting on Jameela's response: 'Can't believe this is actually real,' while another added: 'What kind of mother would advertise appetite suppressants. Jesus Christ they're money hungry.'
Another fan chimed in: 'As a mother this terrifies me, as a woman this boils my blood! Disgusting. No wonder people struggle so much when s*** like this is rammed down your throat. Calls herself a role model?!?'
While another added in despair: 'I hope this isn't real. This woman has far too much influence over young girls & seems incapable of using it in a positive way.'
Meanwhile Kim's post itself was flooded with critical comments from her followers, who branded the ad 'disgusting' and 'irresponsible'.
One wrote: 'This is absolutely disgusting. What a horrible message to send to you impressionable and young female followers. Have you no shame?'
While others added: 'Shouldn't you be encouraging body image positivity instead of encouraging your followers to have appetite suppressants? How sad...'
'THIS IS NOT OKAY! What a way to use your 'celebrity status' to promote dieting and disordered eating behaviours! Shameful.'
And: 'This is a such a dangerous message to be sending from someone in a position such as yours.'
The post was also deemed irresponsible by professionals - with leading Harley Street nutritionist Rhiannon Lambert urging Kim to be more aware of her huge and often impressionable following.
She told MailOnline: 'When these celebs start promoting unhealthy behaviours, they can be taken very seriously by some people which may encourage or lead to disordered eating and an unhealthy relationship with food.
'It is incredibly sad to see posts that are liked by so many individuals, going against everything we as nutritionists are trying so hard to fight. Products such as 'appetite suppressants' have no place in a well balanced diet.'
Kim is known for her presence on social media - sharing both personal posts as well as sponsored content almost daily.
Last year Michael Heller - CEO of the talent firm that organises the family's endorsements – told Us Weekly that Kim earns close to $500,000 per Instagram ad, while her sisters Khloe and Kourtney can bag up to $250,000.
