Prince of Wales Albert Edward (later King Edward VII of the United Kingdom)
Portrait by George Frederic Watts (link)
From Slate Magazine:
"In his profligate youth, the English Prince of Wales—Britain's future King Edward VII (he ruled between 1901 and 1910)—was a celebrity in Paris, thanks to his gargantuan appetites for both food and sex. Perpetually availed of champagne and cigars, his girth filled out by five high-protein meals a day, he would receive a standing ovation at the theater whenever he appeared with a beautiful new paramour on his arm.
( More under here )
I dunno, he doesn't look that fat to me, but perhaps he was by early 1900s standards. Or maybe the Parisian habitues of the brothels were a bit smaller than their Saxe-Coburg counterpart. And that chair looks like a fantastic idea.