The indoor optical wireless channel can be considered as quasi-static multipath channel with inherently low-pass characteristic. Moreover, the visible light communication is usually a power limited system. In order to make full use of the channel spectrum resources and save the energy, the adaptive bit-power loading algorithms of Chow, Hughes-Hartogs and Fischer are applied to the asymmetrically-clipped optical orthogonal frequency division multiplexing (ACO-OFDM) system is proposed. The process of adaptive bit-power loading is introduced, and the performance of the adaptive ACO-OFDM is compared with that of the adaptive direct current optical OFDM (DCO-OFDM). The results show that, compared with the equal bit loading method, the adaptive load algorithm can save about 15% for the optical power and about 30% for the electric power when the performance of bit error rate is guaranteed. Fischer algorithm can save the most optical and electrical power, while Hughes-Hartogs algorithm needs more power. At the same transmit rate, the adaptive ACO-OFDM is more economical than the adaptive DCO-OFDM.