noun
also respiratory ratio
: a ratio indicating the relation of the volume of carbon dioxide given off in respiration to that of the oxygen consumed and having a value near 1 when the organism is burning chiefly carbohydrates, near 0.7 when chiefly fats, and near 0.8 when chiefly proteins but sometimes exceeding 1 when carbohydrates are being changed to fats for storage — abbr. RQ