One of my favorite paintings of a fat and imposing man is the Italian Baroque portrait of the Tuscan nobleman and soldier Alessandro del Borro. Some think Velasquez was the painter; others attribute it to Bernardo Strozzi, probably because of its more naturalistic style.
Del Borro studied mathematics and mechanics, but got drawn into the mid-seventeenth century wars against the Ottoman Empire. His command earned him the title "The Terror of the Turks," and ultimately led to his death in a naval battle against the Ottomans off the coast of Corfu in 1656.
In this painting, you really feel del Borro's size. Monroe Beardsley in Aesthetics: Problems in the Philosophy of Criticism (pg. 300) points out that by bringing del Borro right up to the front of the visual space, the figure doesn't just "tell" of his overwhelming size, but in a way "shows" it:
... Suppose we want to represent a bulky, massive man. We can do so by drawing a small figure at some distance, and setting up the perspective and other objects nearby in such a way that we can read him as a big man, though the shape that represents him is small. But if we bring him up close to the picture-plane, as a portraitist would do, and make him crowd the available picture-space, then the area that represents him will itself be bulky and, if we wish it, massive; here the bulkiness of the man is represented by the bulkiness of the design area. See, for example, Goya's Colossus, Plate VII. We say, colloquially, that we "feel" his bulkiness; we don't merely infer it. [An example is found in] such a painting as the unflattering portrait of Field Captain Alessandro del Borro (date unknown, Kaiser Friedrich Museum, Berlin) attributed, probably incorrectly, to Velasquez. Here the impression of bulk is further increased by placing the Captain between pillars and setting the spectator's eye level at his feet."Unlike Beardsley, I don't think the portrait of del Borro is "unflattering" at all. As I see it, he stands as sturdy as the column next to him. He's not an epicene dandy, or some symbol of self-indulgence. He peers out from behind his small eyes with a beady stare, daring the viewer to challenge him.
The close proximity, and our lowered vantage point, makes him look especially tall. Also, the vantage point adds to the imposing physicality of his size. (ETA:) David Addison Small does the same thing here with the enormous angelic figure. Seattle artist Brian Murphy, whom I wrote about earlier, uses the same perspective in image #12 in his gallery. In both paintings, the belly bears down on the viewer with an almost overpowering weight. Murphy's #13, #15, #16, #18 and #19 also emphasize the size and breadth of the foreshortened face in the same way. (/ETA)
True, del Borro is not "beautiful" in a classical sense. But while fat women in older paintings may often be idealized, the fat man seldom is. We see him "as he is," and are invited to take him on his own terms.