Income mobility forms a part of growth in a society, especially when people move from lower income levels to higher income levels. It is often assumed that people who move to higher income levels are healthier than people who consistently find themselves in low-income groups. With this study, this assumption was tested by using obesity to measure health. Obesity, used as a health risk factor, is one of the results of the nutrition transition where people are moving away from traditional, nutritious foods to less nutritious foods. The prevalence of obesity was tested on a South African sample compiled by the National Income Dynamic Study (NIDS). The study was conducted over five years, or waves, from 2008 to 2017. The questionnaires that form part of the study provided enough data to calculate the Body Mass Index (BMI), as well as the income levels of adults. Respondents were divided into four BMI groups, as well as four income groups. By making use of this group classifications, the prevalence of obesity among the respondents participating in income mobility was tested. The findings of the study show that there is an observed positive relationship between respondents who moved from a lower social class to a higher social class and a BMI increase.