The first bolded part is your own selfish opinion, and not the opinion of God. The fact that you are unable to love a woman who is overweight is a problem within yourself. It has nothing to do with God. Your preferences do not determine what is a sin in God's eyes.
The second bolded part assumes that overweight people are not healthy. Perhaps you should provide your own personal definition of what you consider to be "healthy" and also what you consider to be "fat". It is far from a secret that women who have a little more weight on them are often far healthier than their thinner counterparts. It is also no secret that research shows heavier (curvy) women are also healthier. These women would sometimes be considered "obese" by modern standards.
Now the third bolded statement......
I must be a "fat" guy since I take issue with ignorance. Just like someone who defends blacks must be black, and someone who defends homosexuals must be gay, and someone who defends helpless animals must be.......... well, you know. That logic is just as good as saying that being fat is a sin since it affects your personal ability to love your wife.