A new trend on the Internet is the online health communities, used by many people and for various purposes. This thesis draws a certain attention to online health communities on issues related to established bad, or unhealthy, habits. Communities on overweight, smoking, alcohol and drug abuse are presented, and posted issues as well as patterns of conversations are analyzed from a learning perspective. A holistic approach that considers the relations between the usage of health communities and 'Ask the Expert' systems is also presented. The results indicate that users of the studied online health communities showed great willingness to share experiences and to express sympathy. Different positions, on the other hand, were more seldom used in the conversations. Since most examples of different positions were expressed in a neutral way or combined with empathy, the conversations would probably be able to use this sort of response acts more frequently without jeopardizing community bonds. From a learning perspective, this could be beneficial for the users. Finally, guidelines for how to design holistic health systems are suggested.