Antonyms of healthy:
unfit, unhealthy, turgid, gangrenous, diseased, mortified, icteric, cytomegalic, flatulent, intumescent, foamy, windburned, proinflammatory, gassy, wheezing, morbid, sunburned, inflamed, creaky, edematous, asthmatic, bloodshot, chilblained, frothing, dehydrated, blebby, foaming, blistery, ingrown, pro-inflammatory, yellow, pathological, enlarged, sickly, rheumatic, colicky, sallow, unwholesome, sore-eyed, ingrowing, dropsical, unsound, puffy, pathologic, inconsiderable, bad, caseous, jaundiced, carbuncled, carious, cankerous, ulcerous, tumid, angry, tumescent, membrane-forming, carbuncular, inflammatory, unreasonable, wheezy, mental, ulcerated, arthritic, windburnt, rheumy, rheumatoid, varicose, sunburnt, membranous, delicate, failing, ill, worn, fainting, sick, wasted, worn down, emaciated, fragile, weak, worn out, exhausted, frail, decrepit, enfeebled, feeble, infirm, run-down, sickened, weakened, weakly, challenged, crippled, debilitated, differently abled, disabled, halt, incapacitated, lame, gaunt, haggard, malnourished, undernourished, afflicted, troubled, poorly, ailing, unwell, damaging, deleterious, harmful, injurious, pernicious, infectious, poisonous, sickening, toxic, insanitary, unhygienic, unsanitary, insalubrious, noxious, unhealthful, measly, minute, paltry, petty, picayune, picayunish, piddling, puny, trifling, trivial, unimportant, marginal, meager, slight, little, small, tiny, undersized, bitty, diminutive, miniature, pint-size, pocket, pocket-size, pygmy, smallish, inconsequential, insignificant, insubstantial, negligible, nominal, declining, dying, floundering, languishing, struggling, bankrupt, bankrupted, insolvent, depressed, unprosperous, unsuccessful.
Examples of usage:
  1. She would regret the death of either as she would regret the death of any strong, healthy man; but that was all.
    "In the Brooding Wild", Ridgwell Cullum.
  2. This desire was a healthy and a reasonable one; but, unfortunately, the Antwerpers had not always been so vigorous or so united in their resistance to Parma.
    "Project Gutenberg History of The Netherlands, 1555-1623, Complete", John Lothrop Motley.
  3. The first child had a healthy wet- nurse, and has grown a fine healthy lad.
    "The Maternal Management of Children, in Health and Disease.", Thomas Bull, M.D..