The purpose of this study is to examine whether increased dairy intake, at the level recommended by Canada's Food Guide, combined with healthy eating and exercise, will improve body composition and bone turnover over 12 weeks in overweight and obese girls.
Three groups will participate in this study. Participants must be low dairy consumers (0-1 svgs/d) and do little to no structured physical activity at study entry. Each participant will be assigned to a group; one of two experimental groups or a control group. The two intervention groups will differ only in the amount of dairy consumed (4 svgs vs. 0-1 svg/d). Both will undergo the same exercise program (3x/wk) and will be counseled on healthy eating by a trained nutritionist-dietitian every month. The control group will be tested at the beginning and end of the study to help account for any growth-related changes during the study but will not receive any formal intervention. In each group, the investigators will assess body composition (muscle mass, fat mass, % body fat and regional fat mass) and bone (bone turnover markers). The investigators will also measure various metabolic and inflammatory markers, hormones as well as dietary intake, strength and fitness. This study will determine whether increased intake of dairy products improve bone and body composition during a 12-week weight management intervention. The investigators expect the two groups participating in the intervention to show significant changes in body weight and body composition and greater gains in fitness compared to the control group. The investigators expect those consuming dairy to show greater improvements in body composition and bone health compared to those not consuming added dairy. The investigators also anticipate better vitamin D status and less whole-body inflammation in those consuming dairy. Both intervention groups should show improvements in fasting insulin, glucose and cholesterol.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
61
12 weeks diet and exercise intervention characterized by higher dairy consumption (4 servings per day) and exercise 3 times per week
12 weeks diet and exercise intervention characterized by lower dairy consumption (0-1 serving per day) and exercise 3 times per week
Brock University
St. Catharines, Ontario, Canada
Change in lean mass
body composition: lean mass (kg)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in fat mass
body composition: fat mass (kg)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in % body fat
body composition: % body fat
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in TNF-α
inflammatory marker: tumor necrosis factor alpha (TNF-α; ng/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in IL-6 and IL-1β
inflammatory markers: Interleukin 6 (IL-6; ng/L), interleukin 1 beta (IL-1β; ng/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in Leptin
adipokine: leptin (mg/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in Adiponectin
adipokine: adiponectin (mg/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in lipids
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cardiometabolic risk: lipids (triglycerides, LDL, HDL, total cholesterol; mmol/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in glucose
cardiometabolic risk: glucose (mmol/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in insulin
cardiometabolic risk: insulin (pmol/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in 25OHD
hormone: 25-hydroxyvitamin D (25OHD nmol/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in PTH
hormone: parathyroid hormone (PTH pmol/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Changes in fitness
cardiovascular fitness and response to exercise (heart rate (HR; bpm) , oxygen consumption (VO2 max) using a progressive exercise test to exhaustion.
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in P1NP
bone turnover biomarker: P1NP (ug/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)
Change in CTx
bone turnover biomarker: CTx (nmol/L)
Time frame: 3 times during the study (week 0 pre-intervention; week 12 post-intervention; week 24 follow-up)