Dairy Foods and Weight Loss

Not Applicable

Completed

• Conditions: Overweight and Obesity
• Interventions: Other: high dairy diet; Other: Low Dairy

• Registration Number: NCT00858312
• Lead Sponsor: USDA, Western Human Nutrition Research Center

Brief Summary

Obesity is a national epidemic with multiple causes and complex solutions. Research in both animals and humans has suggested that the inclusion of dairy foods into a moderate calorie restricted diet can increase weight loss and fat loss. Our proposed project extends these prior findings by determining, for the first time, how inclusion of dairy in a calorie-restricted diet changes the amount of visceral adiposity in overweight and obese subjects. The investigators also propose unique studies to evaluate the potential mechanism(s) by which dairy promotes weight and fat loss during dieting, through an examination of adipocyte size, gene expression, and inflammatory markers. The hypotheses under investigation are (1) that inclusion of dairy foods in a modest energy restricted diet will significantly increase body fat loss compared to a control diet; (2) that dairy products in a modest energy restricted diet will result in greater fat loss from intra-abdominal adipose tissue compared to the control, 3) components of dairy products up- or down-regulate the secretion of metabolically-relevant hormones during the postprandial and inter-meal periods, 4) dairy products will promote satiety and/or satiation, 5) dairy foods reduce adipocyte differentiation and/or enhance adipocyte apoptosis, leading to concomitant white adipose tissue (WAT) expression changes for genes playing a role in these processes, 6) dairy foods will reduce adipocyte lipid storage and enhance pathways associated with thermogenesis and mitochondrial function in WAT, as reflected in gene expression changes and reduced adipocyte size, and 7) dairy foods included in a modest energy restricted diet will decrease inflammation in WAT and other tissues, thus decreasing circulating cytokines, increasing zinc status, decreasing expression of inflammatory markers in WAT, and reducing WAT macrophage infiltration.

Detailed Description

84 overweight and overweight and obese adult males and females will be recruited from the faculty, staff, and student populations at University of California-Davis as well as the greater Davis and Sacramento communities. Each intervention arm will require 42 adults; 35 for statistical power on weight loss + 14 more for attrition during the weight loss intervention. Statistical power for fat loss requires only 20 subjects/treatment arm. Subjects will be enrolled in 7 cohorts of 12 each and will be randomly assigned to either control or dairy diets. Subjects will meet the following additional inclusion and exclusion criteria:

Study Timeline

• Study Start: 2006-10
• Study First Submitted: 2009-03-05
• Study First Submitted QC: 2009-03-06
• Study First Posted: 2009-03-09
• Primary Completion: 2009-08
• Study Completion: 2009-08
• Status Verified: 2025-03
• Last Update Submitted: 2025-03-11
• Last Update Posted: 2025-03-14

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 78

Inclusion Criteria

• Body mass index (BMI) 28 -3 4.9 kg/m2
• Age 20-45 years for females, age 20-50 for males
• Low calcium diet (determined by food frequency and diet history): < 1 serving of dairy foods and total dietary Ca intake from all sources not to exceed 600 mg/d .
• No more than 3 kg weight loss during past three months
• Negative pregnancy test at entry prior to DXA and abdominal CT scan; pregnancy testing will be repeated done at 6 weeks of diet intervention to insure that women do not become pregnant during the energy restriction period. Should a woman become pregnant she will be dismissed from the protocol. Pregnancy testing will also be done at the end of the study prior to DXA and abdominal CT scans

Exclusion Criteria

• BMI<28or>37. BMI greater than 37 indicates another level of obesity and the potential for numerous obesity related endocrine changes and substrate utilization abnormalities.

  • Type II diabetes requiring the use of any oral anti-diabetic agent and/or insulin (because of confounding effects on body weight regulation).
  • Fasting glucose > 110 mg/dl.
  • Adverse response to study foods (lactose intolerance, dairy intolerance, dairy allergy; this will be determined by self-report.
  • High calcium diet (determined by food frequency and diet history): Greater than 600 mg calcium per day from all sources (Ca supplements, dairy foods and other dietary sources).
  • History or presence of significant metabolic disease which could impact on the results of the study (i.e. endocrine, hepatic, renal disease).
  • Use of hypertension or lipid altering medications.
  • Resting blood pressure > 160/100 mg/Hg
  • Total cholesterol > 300mg/dl or triglyceride value > 400 mg/dl or LDL > 160 mg/dl.
  • History of eating disorder
  • Presence of active gastrointestinal disorders such as malabsorption syndromes
  • Pregnancy or lactation
  • Use of obesity pharmacotherapeutic agents within the last 12 weeks
  • Use of over-the-counter anti-obesity agents (e.g. those containing phenylpropanolamine, ephedrine and/or caffeine) within the last 12 weeks
  • Use of calcium supplements in the past 12 weeks
  • Recent (past four weeks) initiation of an exercise program
  • Recent (past twelve weeks) initiation of hormonal birth control or change in hormonal birth control regimen
  • Use of tobacco products.
  • Exercise more than 30 minutes/day - greater than this may influence substrate utilization.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
1	high dairy diet	Diet with 3-4 servings of dairy-rich foods/day
2	Low Dairy	Low Dairy \< 1 serving of dairy food/day

Primary Outcome Measures

Name	Time	Method
Change in body weight	measured at end of run-in diet and after 12 weeks of study diet	Weight measured in kg
Change in intra-abdominal adipose tissue (IAAT)	measured at end of run-in diet and after 12 weeks of study diet	Intra-abdominal adipose tissue IAAT volume measured in cubic centimeters using computed tomography (CT) transabdominal slices
Change in body fat	measured at end of run-in diet and after 12 weeks of study diet	Total body fat assessed using dual energy X-ray absorptiometry (DXA)

Secondary Outcome Measures

Name	Time	Method
Change in subcutaneous adipose cell number and size	measured at end of run-in diet and after 12 weeks of study diet	Subcutaneous adipose tissue samples obtained by needle biopsy prepared for histological examination of cell number and size in square micrometers (uM2)
Change in subcutaneous adipose tissue inflammation	measured at end of run-in diet and after 12 weeks of study diet	Subcutaneous adipose tissue samples obtained by needle biopsy were prepared for histological examination of the number of macrophages.
Change in subcutaneous adipose tissue gene expression	measured at end of run-in diet and after 12 weeks of study diet	Subcutaneous adipose tissue samples obtained by needle biopsy were prepared for RNA extraction
Change in insulin	measured at end of run-in diet and after 12 weeks of study diet	Serum insulin concentration (pmol/L) measured using multiplex technology.
Change in glucose	measured at end of run-in diet and after 12 weeks of study diet	Plasma glucose concentration (mmol/L) measured using standard clinical methods
Change in total cholesterol	measured at end of run-in diet and after 12 weeks of study diet	Serum cholesterol concentration (mmol/L) measured using standard clinical methods
Change in low density lipoprotein (LDL) cholesterol	measured at end of run-in diet and after 12 weeks of study diet	Serum LDL cholesterol concentration (mmol/L) measured using standard clinical methods
Change in high density lipoprotein (HDL) cholesterol	measured at end of run-in diet and after 12 weeks of study diet	Serum HDL cholesterol concentration (mmol/L) measured using standard clinical methods
Change in vitamin D (calciferol) metabolites	measured at end of run-in diet and after 12 weeks of study diet	Serum 25-OH Vitamin D (nmol/L) and 1,25 (OH)2 vitamin D concentration (pmol/L) measured using radioimmunoassay (RIA)
Change in leptin	measured at end of run-in diet and after 12 weeks of study diet	Serum leptin concentration (ng/ml) measured using multiplex technology.
Change in adiponectin	measured at end of run-in diet and after 12 weeks of study diet	Serum adiponectin concentration (ug/mL) measured using multiplex technology.
Change in inflammatory cytokines	measured at end of run-in diet and after 12 weeks of study diet	Serum inflammatory cytokine concentration (pg/mL) measured using multiplex technology.
Change in gastric inhibitory peptide (GIP)	measured at end of run-in diet and after 12 weeks of study diet	Serum GIP concentration measured using multiplex technology.
Change in sun exposure	measured twice per week for 12 consecutive weeks of study diet	Sun exposure was estimated from a personal diary kept weekly for recording time outdoors in hourly increments from 7 am to 7 pm combined with a clothing and sunscreen use standard key. Ultraviolet B (UVB) data was collected from various regional climate stations enrolled in the USDA UVB Monitoring Research Program (UVMRP).
Change in skin reflectance	measured at end of run-in diet and after 12 weeks of study diet	Spectrophotometric measure of skin pigmentation for assessment of vitamin D status
Change in high sensitivity C-reactive protein (hs-CRP)	measured at end of run-in diet and after 12 weeks of study diet	Serum hs-CRP concentration (mg/L) measured using immunoassay
Change in amylin	measured at end of run-in diet and after 12 weeks of study diet	Serum amylin concentration measured using multiplex technology.
Change in peptide-YY (PYY)	measured at end of run-in diet and after 12 weeks of study diet	Serum PYY concentration measured using multiplex technology.
Change in cholecystokinin (CCK)	measured at end of run-in diet and after 12 weeks of study diet	Serum CCK concentration measured using radioimmunoassay
Change in salivary cortisol in response to a meal	15 minutes before, and 30, 45 and 60 min after lunch	Cortisol concentration measure by high sensitivity enzyme linked immunoassay (nmol/L)
Change in salivary cortisol in response to a buffet	before and 30 min after buffet	Cortisol concentration measure by high sensitivity enzyme linked immunoassay (nmol/L)
Change in glucagon like peptide-1 (GLP-1)	measured at end of run-in diet and after 12 weeks of study diet	Serum GLP-1 concentration measured using multiplex technology.
Change in salivary cortisol in response to weight loss	measured at end of run-in diet and after 12 weeks of study diet	Cortisol concentration measure by high sensitivity enzyme linked immunoassay (nmol/L)

Trial Locations

Locations (1)

Western Human Nutrition Research Center; 🇺🇸 Davis, California, United States