Visceral fat builds up slowly over time (years) and the changes can be very subtle and unnoticeable until one day you just notice it.
For Kwashiorkor - I really don’t know. It’s just something I’d heard of before, so I found a link to a description and dropped the reference. There are probably lots of other things it could be that I just haven’t heard about.
I, personally, am affected by visceral fat and have been taking steps to lose it and that process is also very slow going, so I currently look like an average guy, but with a pronounced belly. It makes me look like shit in a t-shirt and has caused me to suffer from high blood pressure.