Ugliness in itself is subjective and shouldn't be considered a disease. However, some of the things that people perceive to be ugly like facial or bodily deformities that impair normal function, I guess could be considered as a disease.
5w6 or 9w1 sp/so/sx, I think
I had to convert this into the metric system, but do you mean 1.58 meters and 54 kg??? That is not at all fat, in fact it is in the lower range of normal. You have a BMI of 21,6. Anything between 20 and 25 is normal.
I have the same height and usually weigh around 52 kg (varying between 51 and 54 kg for over a decade now) and people compliment me on my slim figure. If you had just a few kg less on our ribs you'd be clinically underweight.
Your problem seems to be psychological rather than physical.
The good life is one inspired by love and guided by knowledge. Neither love without knowledge, nor knowledge without love can produce a good life. - Bertrand Russell A herring's blog Johari / Nohari
"An upsidedown wire heart
Being sucked into a periscope
Still the mind is dull
Like you need another excuse"
… a theory is primarily a form of insight, i.e. a way of looking
at the world, and not a form of knowledge of how the world is….
.. all our different ways of thinking are to be considered as
different ways of looking at the one reality, each with some
domain in which it is clear and adequate…. - David Bohm