An observational study in Obesity, Weight Change, Body and Weight Loss, sponsored by University of Colorado, Denver. Completed at 1 site in United States. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2018-02-05.
Sponsored by University of Colorado, Denver · Observational
Obesity is reaching epidemic proportions and threatens both health and quality of life of people around the world. While many individuals succeed at short term weight loss, weight loss maintenance is the greatest barrier to successful treatment of obesity. High levels of physical activity are consistently associated with success in weight loss maintenance. The major goal of this proposal is to understand how and why high levels of physical activity are critical for long term maintenance of weight loss. This project takes advantage of the National Weight Control Registry (NWCR), which follows over 6000 individuals who have maintained a weight loss of ≥30 pounds for ≥1 year. Understanding how individuals successful at weight loss maintenance achieve energy balance will provide important insight into strategies to help more people sustain a weight loss.
Participants were recruited in three groups: weight loss maintainers (WLM: maintaining ≥13.6 kg weight loss for ≥1 year), normal weight controls (NC: Body Mass Index (BMI) matched to current BMI of WLM), and controls with overweight/obesity (Overweight Controls (OC): BMI matched to pre-weight loss maximum BMI of WLM). The investigators hypothesize that total daily energy expenditure (TDEE) in WLM is similar to OC but is significantly higher then NC. High levels of volitional physical activity may compensate for the reduction in energy expenditure ("energy gap") that is the expected result of weight loss. This allows WLM to maintain a high level of "energy flux", which may facilitate optimal body weight regulation over time. The investigators will use doubly labeled water to compare TDEE in WLM and both NC and OC. The investigators will also compare individual components of TDEE including resting energy expenditure (REE), thermic effect of food (TEF), physical activity energy expenditure (PAEE), and physical activity level (PAL) between groups. The investigators also hypothesize that REE in WLM is similar to controls of both types under free living conditions, but will decrease following a period of physical inactivity and be significantly less than controls. Studies in rodents have consistently shown evidence of an increase in metabolic efficiency in the reduced obese state manifested by a lower than predicted REE. Studies in humans have shown mixed results, however few studies have controlled for habitual level of physical activity. Recent evidence suggests REE is greater in adults who perform regular exercise than their sedentary peers; this difference can be attributed in part to greater tonic sympathetic nervous system stimulation of REE that occurs in habitually exercising adults. The investigators believe there is an increase in metabolic efficiency in the reduced obese state manifested by a lower than predicted REE, and that high levels of physical activity function to "mask" or "correct" this metabolic efficiency. The investigators will compare REE under free living conditions and during an experimentally imposed period of reduced energy flux (restricted physical activity matched by an equivalent reduction in energy intake) in WLM and controls.
11,522 studies on the registry are indexed under Obesity; 2,033 are open to participants now.
This study's enrollment of 112 is close to the median of 114 across 2,154 observational studies indexed under Obesity.
Browse Obesity studies →University of Colorado, Denver is the lead sponsor of 1,543 studies on the registry; 317 are open to participants now.
Of its 147 completed or terminated interventional studies of FDA-regulated products, 92 (63%) have results posted.
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The proposed study design is aimed at collecting additional data on previously enrolled adult study subjects in the NWCR, which does not include children. The NWCR contains approximately 70% women and 30% men. We anticipate studying equal numbers of men and women in this study. Minorities comprise approximately 7% of total subjects in the NWCR. In the proposed studies, there will be no exclusions for racial or ethnic background.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Individuals maintaining ≥13.6 kg (30 lb) weight loss for ≥1 year
Individuals with normal weight whose BMI was matched to the current BMI of the WLM. NC had to be weight stable and not maintaining a weight loss of ≥13.6kg
Individuals with overweight/obesity whose BMI was matched to the pre-weight loss maximum BMI of WLM. OC had to be weight stable and not maintaining a weight loss of ≥13.6kg
Total Daily Energy Expenditure (TDEE)
After a 12-hour overnight fast, participants provided a baseline urine sample on day 1. Participants were then administered an oral dose of doubly labeled water (DLW) containing 1.8g 10% 18O/kg total body water (TBW) and 0.12 g/kg TBW of 99.9% deuterium. TBW was estimated as 73% of FFM from DXA. The dosing cup was rinsed twice with 30 mL of water and the rinsing dose consumed. Exact time of dosing was recorded. Additional urine samples were collected after a 4hr and 5hr post-dose equilibrium period and then again at the same times on day 8. TDEE over days 1-8 was determined using a single DLW dose and the two-point method according to Schoeller and colleagues.
Time frame: At 8 days
Physical Activity Energy Expenditure (PAEE)
PAEE was calculated as TDEE - TEF - REE. In addition, because the energy cost of PA is proportional to body weight for a given intensity and duration, PAEE was also calculated as relative to body weight (kg).
Time frame: At 8 days
Resting Energy Expenditure (REE)
REE was measured using standard indirect calorimetry (Truemax 2400, ParvoMedics, Salt Lake City, UT) with the ventilated hood technique. Study participants arrived at 7am after a 12-hour overnight fast. Participants rested supine, awake, and lightly clothed in a thermoneutral (68-74 ˚F), dimly lit, quite room for 30 minutes. Respiratory gas exchange was measured for 15 minutes, using the last 10 minutes to average REE. Tests were examined for validity to confirm a) average RQ was 0.7-0.9, and b) average Metabolic Equivalents (METs) \<1.10. If the averaged data fell outside of these ranges, the test was considered invalid and excluded from the analysis. REE was collected on days 1 and 8 of the free-living monitoring period, and averaged to produce a single value for REE (intraclass correlation coefficient = 0.96).
Time frame: Day 1 and Day 8 over a 1 week period
Thermic Effect of Food (TEF)
The thermic effect of food (TEF) was calculated as 10% of TDEE.
Time frame: At 8 days
Physical Activity Level (PAL)
PAL was calculated as TDEE/REE.
Time frame: At 8 days
Physical Activity Patterns
PA patterns were assessed using the activPALTM activity monitor (PAL Technologies, Glasgow, Scotland). The activPALTM is a small (23x43x5 mm) and lightweight (10 grams) device that uses accelerometer-derived information about thigh position to estimate time spent sitting/lying, standing, and stepping. The device is attached to the anterior thigh and is waterproofed by wrapping it in a nitrile sleeve, allowing for 24-hour measurement. Participants were asked to wear the device continuously for seven days.
Time frame: At 8 days
Ran from Oct 2009 to primary completion in Sep 2012, 35 months.
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This study is completed, as verified in Jan 2018. You cannot join it, but the record below documents what was studied.
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