Nice picture of Hadad. He certainly is fatter than Isner although he comes doesn't close in weight. At 6 feet even if he's only 195 lbs his body mass index (BMI) is higher than Isner's (26.44 vs 26.25). Michael Berrer has the highest BMI I could find among active players 27.5.
Nadal, Nic Monroe, Marcus Willis, Groth, Tursunov