I think this is why they say "Trigger Warning", only in this case, not:

I have seen some pictures on Facebook that show pictures of starving, emaciated people.

For example, on gay marriage, one would have a picture of a gay couple and a starving child, and say "if this [the gay couple] offends you more than this [starving child], you need to check your values".

I find pictures of people suffering to be unsettling, and starvation/emaciation especially so.

But apart from my squeamishness, I think it is ethically wrong and exploitative to use pictures of people suffering to make a point. It is also borderline racist, in that it depicts a stereotypical starving African. Africa has aspects of its culture and history other than suffering so we can make rhetorical points.

There might be people who have differences with me on this matter, but I think of these types of image as particularly tasteless propaganda.