MRI structural scanning of the body has been used in a study of the weight-loss treatment Orlistat (sold as ‘Alli’ in the UK). The MRI images in this case were used to quantify the amount of fat lost over a 3-month period, while the subjects were following a calorie-controlled diet and also using Alli. Overall weight loss is clearly very simple to measure with an ordinary bathroom scale, but what the MRI images showed was that a substantial proportion of visceral fat (fat that accumulates internally around the body organs, highlighted orange on the image) was lost, as well as subcutaneous fat. This is important because visceral fat deposits are thought to be more dangerous to health and is associated with health problems such as type 2 diabetes. These results were published in the following paper:
Thomas, E. L., Makwana, a, Newbould, R., Rao, a W., Gambarota, G., Frost, G., … Beaver, J. D. (2011). Pragmatic study of orlistat 60?mg on abdominal obesity. European Journal of Clinical Nutrition, 65(11), 1256–62. doi:10.1038/ejcn.2011.108.