DAWL (Dairy and 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.
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.
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.
|Study Design:||Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
|Official Title:||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|
- Body fat [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]Whole body fat will be measured at baseline (Week 0) and follow-up (Week 16) by dual energy x-ray absorptiometry
- Body weight [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]The investigators will measure body weight every 2 weeks during the trial
- Body mass index (BMI) [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]Body mass is weight (in kg) divided by height (in m2), to be measured every 2 weeks
- Waist and hip circumference [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]The investigators will measure waist and hip circumference, using a measuring tape, every 2 weeks throughout the trial.
- Fat-free mass [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]Similar to fat mass, the investigators will measure fat-free mass at weeks 0 and 16, using dual energy x-ray absorptiometry
- Biochemistry [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]The investigators will measure various biochemical variables at weeks 0 and 16. These will include: glucose, insulin, lipid panel (triglyeride, total cholesterol, HDL cholesterol, LDL cholesterol), vitamin D, parathyroid hormone, C-reactive protein, conjugated linoleic acid concentrations of red blood cells, and hepatic lipase and lipoprotein lipase
- Blood pressure [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]The investigators will measure blood pressure every two weeks during the study.
|Study Start Date:||May 2012|
|Estimated Study Completion Date:||December 2014|
|Estimated Primary Completion Date:||December 2014 (Final data collection date for primary outcome measure)|
Active Comparator: Lifestyle counselling
These participants will be assigned to a 500 kcal/day energy-restricted diet that is low in dairy products (no more than 1 serving per day).
Other: Low dairy
No more than 1 serving per day
Experimental: High dairy
These participants will be assigned a 500 kcal/day energy-restricted diet that is high in dairy (4 or more servings per day).
Other: High dairy
4 or more servings per day
Show Detailed Description
|Body Composition and Metabolism Lab, University of Guelph|
|Guelph, Ontario, Canada, N1G 2W1|
|Principal Investigator:||Andrea C. Buchholz, PhD, RD||University of Guelph|