Kiba wani yanayi ne na likitanci wanda yawan kitsen jiki ya taru ta yadda zai iya yin illa ga lafiya. Yawanci ana ɗaukar mutane masu kiba idan ma'aunin jikinsu (BMI), ma'aunin da ake samu ta hanyar raba nauyin mutum da murabba'in tsayin mutum, ya wuce 30 kg/m2; An bayyana kewayon 25-30 kg/m2 azaman kiba. Wasu ƙasashen Gabashin Asiya suna amfani da ƙananan ƙima. Kiba yana ƙara yuwuwar kamuwa da cututtuka da yanayi daban-daban, musamman cututtukan zuciya da jijiyoyin jini, nau'in ciwon sukari na 2, bugun barci mai hanawa, wasu nau'ikan cutar kansa, osteoarthritis, da damuwa. Yawan kiba yana faruwa ne ta hanyar haɗuwa da wuce kima da abinci, rashin motsa jiki, da lahani na kwayoyin halitta. Wasu lokuta ana haifar da su ta farko ta kwayoyin halitta, cututtukan endocrine, magunguna, ko rashin hankali. Ra'ayin cewa mutane masu kiba suna cin abinci kaɗan duk da haka suna samun nauyi saboda jinkirin metabolism ba a tallafawa ta hanyar likitanci. A matsakaita, mutane masu kiba suna da yawan kashe kuzarin kuzari fiye da takwarorinsu na yau da kullun saboda kuzarin da ake buƙata don kula da yawan adadin jiki.