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Trial registered on ANZCTR


Registration number
ACTRN12616001029482
Ethics application status
Approved
Date submitted
30/07/2016
Date registered
3/08/2016
Date last updated
7/07/2017
Type of registration
Prospectively registered

Titles & IDs
Public title
The effects of yo-yo dieting on whole-body and fat tissue metabolism in pre-menopausal obese women undergoing bariatric surgery
Scientific title
The effects of yo-yo dieting on whole-body and fat tissue metabolism in pre-menopausal obese women undergoing bariatric surgery
Secondary ID [1] 289784 0
None
Universal Trial Number (UTN)
Trial acronym
YOYO
Linked study record

Health condition
Health condition(s) or problem(s) studied:
obesity 299711 0
diabetes 299712 0
Condition category
Condition code
Diet and Nutrition 299647 299647 0 0
Obesity
Metabolic and Endocrine 299670 299670 0 0
Diabetes

Intervention/exposure
Study type
Observational
Patient registry
False
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
This is a longitudinal observational study to examine clinical phenotypes and adipose tissue characteristics of weight-cyclers vs non-cyclers. Pre-menopausal obese women undergoing bariatric surgery will be recruited and followed up for 2 years. Prior to surgery, patients will fill in a validated questionnaire to categorise them into weight cyclers or non-weight cyclers and body composition (DXA) and resting metabolic rate (hand-held respirometer) will be measured. At the time of surgery, a fasting blood sample and subcutaneous and visceral adipose tissue biopsies will be obtained. Participants will return to the clinic at 6, 12 and 24 months to measure anthropometry, resting metabolic rate and body composition.
Intervention code [1] 295474 0
Not applicable
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 299113 0
Change in resting metabolic rate using a hand-held respirometer
Timepoint [1] 299113 0
6 months post bariatric surgery
Secondary outcome [1] 326224 0
Change in body composition measured by DXA scan

Timepoint [1] 326224 0
6, 12 and 24 months post bariatric surgery
Secondary outcome [2] 326283 0
Changes in blood levels of glucose, insulin, HbA1c and lipids measured using laboratory assays
Timepoint [2] 326283 0
6, 12 and 24 months post bariatric surgery
Secondary outcome [3] 326284 0
Change in resting metabolic rate measured by hand-held respirometer
Timepoint [3] 326284 0
12 and 24 months post bariatric surgery
Secondary outcome [4] 326324 0
Blood levels of inflammation (c-reactive protein, interleukin 6) measured by laboratory assay
Timepoint [4] 326324 0
Baseline
Secondary outcome [5] 326325 0
Inflammation gene expression levels in adipose tissue measured by qPCR
Timepoint [5] 326325 0
Baseline

Eligibility
Key inclusion criteria
Premenopausal women aged 20-45y seeking elective surgical treatment for obesity and with a body mass index >30kg/m2
Minimum age
20 Years
Maximum age
45 Years
Gender
Females
Can healthy volunteers participate?
No
Key exclusion criteria
-Diabetes diagnosed more than 5 years ago
-Previous bariatric surgery
-Any metal implants/devices
-Women on a commercial weight management program at preoperative appointment
-Women with active gastrointestinal disease (eg. IBD)
-Women who are pregnant or unwilling to avoid pregnancy for 2 years post-operatively
-Women taking medication that may affect energy expenditure (eg. beta blockers, antipsychotic medication)

Study design
Purpose
Natural history
Duration
Longitudinal
Selection
Convenience sample
Timing
Prospective
Statistical methods / analysis
This is an exploratory study comparing examining resting metabolic rate, body composition and circulating and adipose tissue expression profiles of women classified as weight cyclers vs non-weight cyclers via self-report questionnaire.

We aim to recruit 100 obese women. Given that weight cycling is estimated to occur in 30% of the population, we anticipate classifying 30 women/group as weight cyclers vs non/less severe weight cyclers. This sample size is similar to previously published studies in this area. Our target sample size of 100 women was chosen in order to provide a large enough sample size to successfully stratify the cohort into weight cyclers vs non/less severe weight cyclers,

Statistics. We will use Independent Samples T-test/Mann Whitney U to test comparisons in clinical and adipose tissue characteristics between participants classified as weight cyclers vs non-weight cyclers. Regression analyses (general linear models) will be used to test whether weight cycling status at baseline is associated with weight loss or changes in cardio-metabolic markers at follow-up time-points.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 294188 0
Charities/Societies/Foundations
Name [1] 294188 0
Rebecca L Cooper Medical Research Foundation
Address [1] 294188 0
PO Box 1021, Edgecliff, NSW, 2027
Country [1] 294188 0
Australia
Primary sponsor type
Individual
Name
A/Prof Michael Talbot
Address
Suite 3, Level 5, St George Private Medical Centre, 1 South St, Kogarah, NSW, 2217
Country
Australia
Secondary sponsor category [1] 293013 0
Individual
Name [1] 293013 0
Dr Charmaine Tam
Address [1] 293013 0
Level 3 West 80, Charles Perkins Centre (D17), John Hopkins Drive, University of Sydney, Camperdown, NSW, 2050
Country [1] 293013 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 295591 0
UNSW Human Research Committee
Ethics committee address [1] 295591 0
The University of New South Wales
UNSW Sydney, NSW, Australia, 2052
Ethics committee country [1] 295591 0
Australia
Date submitted for ethics approval [1] 295591 0
31/03/2016
Approval date [1] 295591 0
04/07/2016
Ethics approval number [1] 295591 0
HC16232

Summary
Brief summary
Weight cycling (yo-yo dieting) is an ongoing battle for many obese individuals and is commonly believed to impair energy metabolism and promote future weight gain. However, scientific evidence for this idea remains scarce and mechanisms of how this occurs has not been examined in humans.

The aim of this study is to investigate whether weight-cyclers have impaired energy metabolism, greater fat deposition and greater circulating and fat tissue inflammation compared to non-cyclers.

100 overweight/obese women undergoing bariatric surgery will be recruited into this study. 60 women (30/group) will be classified as weight-cyclers or non-cyclers using a validated questionnaire. Blood and fat tissue samples will be collected at the time of surgery and markers of inflammation measured in the laboratory. Clinic visits will be performed at baseline prior to surgery and at 6, 12 and 24 months after surgery. Measurements include anthropometry, body composition, resting metabolic rate and circulating markers of cardiometabolic disease (glucose, insulin, HbA1c, lipids, inflammation).

Using a rigorous scientific approach and comprehensive clinical phenotyping we will address whether individuals who weight cycle have reduced energy expenditure and greater fat deposition. These results will assist in tailoring personalised weight loss treatment strategies for the over 70% of Australians affected by overweight and obesity.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 67806 0
A/Prof Michael Talbot
Address 67806 0
Suite 3, Level 5, St George Private Medical Centre, 1 South St, Kogarah, NSW, 2217
Country 67806 0
Australia
Phone 67806 0
+61 2 9553 1120
Fax 67806 0
Email 67806 0
m.talbot@unsw.edu.au
Contact person for public queries
Name 67807 0
Dr Charmaine Tam
Address 67807 0
Level 3 West 80, Charles Perkins Centre (D17), John Hopkins Drive, University of Sydney, Camperdown, NSW, 2050
Country 67807 0
Australia
Phone 67807 0
+61 2 8627 1716
Fax 67807 0
Email 67807 0
charmaine.tam@sydney.edu.au
Contact person for scientific queries
Name 67808 0
Dr Charmaine Tam
Address 67808 0
Level 3 West 80, Charles Perkins Centre (D17), John Hopkins Drive, University of Sydney, Camperdown, NSW, 2050
Country 67808 0
Australia
Phone 67808 0
+61 2 8627 1716
Fax 67808 0
Email 67808 0
charmaine.tam@sydney.edu.au

No information has been provided regarding IPD availability
Summary results
No Results