Diet and Weight Loss Study - a Weight Loss Trial to Determine Whether Dairy Products Augment Weight Loss for Adults Following an Energy-restricted Weight Loss Study

* Objectives Taking a \'whole foods\' approach, we will investigate (i) whether consumption of isocaloric diets containing ≥4 vs. ≤1 servings of dairy products per day for 16 weeks results in greater body fat loss in energy-restricted overweight/obese premenopausal women; (ii) the role of dairy product consumption in influencing physiological and metabolic factors which may precede or accompany changes in body composition, including in enzymes which synthesize and break down body fat; and (iii) factors, including obesity phenotype, which may influence the response of body composition to dairy product consumption. * Background With the obesity epidemic showing no signs of abating, there is ongoing interest, both at the lay public and scientific levels, in manipulating the diet to promote weight, specifically fat, loss. One such promising manipulation is an increase in, or perhaps more precisely, an isocaloric substitution of, dairy product consumption. The inverse association between Body Mass Index (BMI) and dietary calcium - for which dairy products are the main source - was first described in 1984 and has since been supported by various levels of evidence, but not consistently. Heaney recently described this literature as \"confused,\" which he and Rafferty attribute to important limitations in study design, including lack of low-calcium contrast groups and the fact that body weight/body composition is often a secondary endpoint in studies designed and powered for a different outcome, typically bone health or blood pressure. Confusion has also arisen from the investigation of different interventions (dairy products, dairy calcium, dietary calcium, supplemental calcium), making it difficult to compare and interpret studies. This creates an opportunity for the proposed Dairy and Weight Loss (DAWL) study, with its focus on whole dairy product consumption, to help clear up the confusion surrounding this issue. \*\*Hypotheses Overweight/obese, low habitual dairy consuming, premenopausal women randomized to an energy-restricted weight loss diet containing ≥4 servings/day of dairy products (milk, yogurt, cheese) for 16 weeks will lose more body fat than those randomized to an isocaloric diet containing ≤1 servings/day of dairy products.