Does Dairy Benefit Bone & Body Composition in Overweight Girls Undergoing a Weight Management Program?

Effects of a Weight Management Intervention With Increased Dairy Intake on Body Composition and Bone Health in Overweight and Obese Girls.

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.

Inclusion Criteria:

• at or above the age appropriate cut-offs for overweight (OW) or obese (OB) on WHO growth charts: ≥85-97% for OW and >97% for OB for BMI
• between 10 and 18 years old
• menarcheal
• low dairy consumers (0-2 svgs/d and <700 mg Ca/d measured by baseline FFQ)
• otherwise healthy (i.e. no diagnosed disease or illness)
• lower levels of physical activity (0-2 times/week)
• no allergy to dairy foods or diagnosed lactose intolerance
• not on medications related to a chronic condition or that affect bone health

Participants will be excluded from participation in the study if they do not meet one or more of the above inclusion criteria.