This thesis explores the ways in which messages and images of relevance to women's and to men's health have been presented to them by the mass media during a period of changing social attitudes to health and gender relations. The context for the research has been the growth, since the 1970s, in the attention given to the impact of lifestyle on health, both generally and in association with the substantial differences that exist in the patterns of women and men's health. This context determined both the time frame for the study, and the strategy for operationalising health. The focus on lifestyle and associated health outcomes effectively extended the boundaries of health to take in the broader issues of management and use - or social constructions - of the body. This broad perspective on health brought the research into the newly developing area of the sociology of the body, and - as a result - the content analysis instrument that was developed was designed to have the capacity to examine the wide range of media content that covered the scope of this study. The research medium that was selected for analysis was the mass magazine, and three publications were selected on the basis that they were general interest magazines which primarily targeted either women or men as their readership. This, then, enabled comparisons of the specific constructions of the body developed for these two target groups. The scope of the study made it appropriate to conduct a comprehensive analysis of whole magazines, enabling comparisons of the editorial and the advertising content. Finally, the magazines that were selected could be compared over time, with samples drawn from three survey years, representing different eras in health thinking: 1952, 1970 and 1988. Three research questions were addressed: the extent to which there was gender stereotyping of the health-related subject matter, the extent to which there have been changes in construction of health and the body over the survey years, and the extent to which the health-related content was generated and constructed by advertisements and a consumer culture agenda. The results provided a partial substantiation of the presence of gender stereotyping, particularly rigidly sustained in the women's magazine. There was also some evidence - in all three periodicals - of changes over time. These were consistent with, but relatively minor reflections of, contemporary social changes. The most significant findings of this research were generated by the comparisons of advertising and editorial content, which demonstrated the dominant role that advertisements can have in the commercial media, in constructing the body in ways of direct and indirect relevance to health. The thesis therefore concludes with a discussion about the implications of these results for women, as the principal consumer group, and for public health strategists involved in the development of initiatives such as media advocacy, consumer education and health literacy.