Minus the skin, it's quite lean
Like beauty, fat on a duck is only skin deep. It doesn't streak through the muscle as in beef. So when you skin a duck, which is easy, you end up with meat that competes with chicken for leanness. And as an alternative to the ubiquitous chicken breast, duck breast is not only a relief, it's also juicier and more flavorful.
However, that duck skin doesn't have to go to waste. Roast it separately.
The breast of Pekin duck, the bird typically sold whole at the market (and used in the Chinese dish Peking duck), is worth the effort to get. Usually it's available by special order at a poultry or meat market or the meat counter at a supermarket (allow one or two days). Boned Pekin breasts run $7 to $12 a pound. Another choice, Muscovy duck breasts, are stronger-tasting and sometimes more expensive, but the meat becomes much milder with this recipe's salt-sugar cure.