Governments and major national agencies throughout the western world concerned with chronic disease prevention (heart disease, stroke, diabetes, and cancer) uniformly advocate increased intakes of fruit, vegetables and whole grain cereals. All also agree that body weight reduction is central to reducing the risk of heart disease, stroke, type 2 diabetes, and certain cancers. Nevertheless, there is no official advice encouraging increased consumption of these foods in order to achieve and maintain a healthy body weight. Most importantly, there are no intervention studies that have tested the assumption that increased intake of fruit, vegetables and whole grain cereals will promote a healthier body weight. Our study will therefore address this issue to determine the effect of an increased intake of fruit, vegetables, and whole grain cereals on body weight, the intensity of effort required to achieve compliance, the durability of this habit, genetic determinants, and the effect on biomarkers of chronic disease risk.