NC: Cardiovascular Disease Risk Factors (2007-2008)
The primary purpose of this study was to examine the short-term effects of a weight loss program focusing on reducing percentage energy from fat, increasing exercise and multi-vitamin or mineral supplementation on serum plasma concentrations of CVD risk factors and regional body composition in overweight men and women.
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Healthy
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No endocrine, orthopedic or other pathological disorders
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Overweight, body fat greater than 20%.
None
- Recruitment: Unknown
- Design: Subjects participated in an eight-week weight loss program. A comparison control group did not participate in the program.
- Blinding used: None
- Intervention: The weight-loss program followed general guidelines for reducing dietary fat and increasing exercise, as well as instruction on behavior modification and nutritional supplementation
- Statistical analysis:
- All data was presented as means and standard deviations
- Dependent variables were analyzed using a two-way analysis of variance with gender (men vs. women) and time (baseline vs. week eight)
- When a significant F-value was achieved, a Fisher’s LSD test was used to located the pairwise differences between means
- Pearson correlation coefficients were used to determine associations between leptin and other variables
- Statistical power ranged from 0.78 to 0.80 at a P-value equal to 0.05 for the various dependent variables
- The level of significance was set at P<0.05.
Timing of Measurements
Initial measurements and at the end of the eight-week program.
Dependent Variables
- Self-documentation of food and beverage intake, exercise training duration and intensity and daily achievement toward nutritional, exercise and behavioral goals
- Body composition and circumferences. Body Mass was determined on a calibrated clinical scale. Two circumference measurements were made on the right side of the body. Body composition was obtained by dual-energy X-ray absorptiometry (DEXA) using a total body scanner.
- Blood collection and analysis: Blood was obtained after a 12-hour overnight fast at the same time of the morning before and after the study.
- Total cholesterol
- LDL-cholesterol
- HDL-cholesterol
- Triacylglycerols
- Homocysteine
- Insulin
- Leptin.
Independent Variables
- The weight-loss program followed general guidelines for reducing dietary fat and increasing exercise, as well as instruction on behavior modification and nutritional supplementation
- Subjects consumed a self-selected diet in a free-living environment
- Subjects were required to attend weekly group meetings led by an RD.
Control Variables
Eight men were asked not to change their diet or activity patterns for eight weeks.
- Initial N: 22 (12 women; 10 men)
- Attrition (final N): None noted
- Age: Women: 42.4±7.7 years; men 39.7±11.0 years
- Ethnicity: None noted
- Other relevant demographics: None noted
- Anthropometrics: Women: 35 to 57% body fat; men: 20 to 40% body fat
- Location: The Human Performance Laboratory at the University of Connecticut, Storrs, Connecticut.
Variables |
Women (N=12) Measures and Confidence Intervals |
Women (N=12) Measures and Confidence Intervals |
Men (N=10) Measures and Confidence Intervals |
Men (N=10) Measures and Confidence Intervals |
Statistical Significance of Group Difference |
Nutrients
|
Week One
|
Week Eight |
Week One |
Week Eight |
Statistically significant difference between groups (e.g., P=0.002) |
Energy | |||||
Protein (grams) | 5.74±1.08 | 4.65±1.39* | 7.74±1.60 | 6.71±1.88* | |
Protein (percentage) | 57±15 | 50±13 | 84±15 | 74±27 | |
Carbohydrate (grams) | 17±14 | 18±2 | 18±2 | 18±3 | |
Carbohydrate (percentage) | 200±62 | 152±64* | 259±71 | 242±57 | |
Fat (grams) | 56±9 | 54±13 | 55±10 | 60±6 | |
Fat (percentage) | 40±10 | 34±17 | 55±22 | 41±17 | |
Saturated fat (grams) | 26±7 | 27±12 | 26±10 | 22±5 | |
Cholesterol (milligrams) | 13±5 | 12±6 | 17±9 | 17±7 | |
Dietary fiber (grams) | 160±90 | 124±100 | 205±106 | 134±74 | |
Folic Acid (microgram) | 16±7 | 12±8* | 17±4 | 15±6 | |
Vitamin B6 (milligrams) | 223±68 | 183±127 | 293±149 | 339±170 | |
Vitamin B6 (milligrams) | 1.2±0.4 | 1.0±0.4 | 2.0±0.9 | 1.9±0.9 | |
Vitamin B12 (microgram) | 2.3±1.4 | 1.9±1.4 | 5.2±3.0 | 4.8±2.2 | |
Body Composition |
Change after eight weeks (Women) |
Change after eight weeks (Men) |
Interaction effect (P) |
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BM kilogram (scale) | -4.3±3.4* | -4.7±3.1* | 0.795 | ||
BM kilogram (DXA) | -3.8±3.3* | -4.2±4.1* | 0.825 | ||
FFM (kilogram) | -1.4±1.7 | -0.4±2.6 | 0.315 | ||
FM (kilogram) | 2.5±2.4* | -3.7±2.3* | 0.209 | ||
Percentage of Fat |
-1.0±2.0 |
-2.7±1.7
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0.045
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Serum Values |
Change after eight weeks (Women) |
Change after eight weeks (Men) |
Interaction effect (P) |
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Total Cholesterol (mg/dl) | -6±18 | -18±14* | 0.102 | ||
LDL Cholesterol (mg/dl) | -4±17 | -14±14* | 0.135 | ||
HDL Cholesterol (mg/dl) | -1±6 | 1±7 | 0.525 | ||
Triglycerols (mg/dl) | -7±44 | -23±72 | 0.513 | ||
Leptin (umol/l) | -16.2±0.8 | -3.9±0.6 | 0.017 | ||
Insulin (pmol/l) | 4±40* | -4±31 | 0.603 | ||
Homocysteine(umol/l) | 0.3±1 | 0.0±0.9 | 0.574 |
*P≤0.05= main effect (baseline vs. week eight)
Other Findings
An additional conclusion reached by these authors is that supplementation with folic acid may be an important component of a weight loss program to prevent increases in homocysteine.
Overweight subjects that made moderate changes in self-selected diet, exercise patterns and supplementation in a free-living environment demonstrated improvements in total and regional body composition and blood lipid profiles.
Industry: |
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- A short (eight-week) weight loss program that emphasized dietary fat restriction, nutritional supplementation, weekly behavior modification support group meetings and a supervised structured exercise program was able to demonstrate positive changes (in CVD risk factors) in a small group of subjects
- An additional conclusion reached by these authors is that supplementation with folic acid may be an important component of a weight loss program to prevent increases in homocysteine.
Quality Criteria Checklist: Primary Research
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Relevance Questions | |||
1. | Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) | Yes | |
2. | Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? | Yes | |
3. | Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? | Yes | |
4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | Yes | |
Validity Questions | |||
1. | Was the research question clearly stated? | Yes | |
1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
1.3. | Were the target population and setting specified? | Yes | |
2. | Was the selection of study subjects/patients free from bias? | ??? | |
2.1. | Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? | ??? | |
2.2. | Were criteria applied equally to all study groups? | ??? | |
2.3. | Were health, demographics, and other characteristics of subjects described? | ??? | |
2.4. | Were the subjects/patients a representative sample of the relevant population? | ??? | |
3. | Were study groups comparable? | N/A | |
3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | ??? | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | Yes | |
3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | Yes | |
3.4. | If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? | N/A | |
3.5. | If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) | Yes | |
3.6. | If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? | N/A | |
4. | Was method of handling withdrawals described? | N/A | |
4.1. | Were follow-up methods described and the same for all groups? | N/A | |
4.2. | Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) | N/A | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
4.4. | Were reasons for withdrawals similar across groups? | N/A | |
4.5. | If diagnostic test, was decision to perform reference test not dependent on results of test under study? | N/A | |
5. | Was blinding used to prevent introduction of bias? | N/A | |
5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | N/A | |
5.2. | Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) | N/A | |
5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | N/A | |
5.4. | In case control study, was case definition explicit and case ascertainment not influenced by exposure status? | ??? | |
5.5. | In diagnostic study, were test results blinded to patient history and other test results? | N/A | |
6. | Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? | N/A | |
6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | N/A | |
6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | N/A | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | Yes | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | Yes | |
6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | Yes | |
6.6. | Were extra or unplanned treatments described? | N/A | |
6.7. | Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? | N/A | |
6.8. | In diagnostic study, were details of test administration and replication sufficient? | N/A | |
7. | Were outcomes clearly defined and the measurements valid and reliable? | Yes | |
7.1. | Were primary and secondary endpoints described and relevant to the question? | Yes | |
7.2. | Were nutrition measures appropriate to question and outcomes of concern? | Yes | |
7.3. | Was the period of follow-up long enough for important outcome(s) to occur? | Yes | |
7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | Yes | |
7.5. | Was the measurement of effect at an appropriate level of precision? | Yes | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | Yes | |
7.7. | Were the measurements conducted consistently across groups? | Yes | |
8. | Was the statistical analysis appropriate for the study design and type of outcome indicators? | Yes | |
8.1. | Were statistical analyses adequately described and the results reported appropriately? | Yes | |
8.2. | Were correct statistical tests used and assumptions of test not violated? | Yes | |
8.3. | Were statistics reported with levels of significance and/or confidence intervals? | Yes | |
8.4. | Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? | Yes | |
8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | ??? | |
8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
8.7. | If negative findings, was a power calculation reported to address type 2 error? | N/A | |
9. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
9.1. | Is there a discussion of findings? | Yes | |
9.2. | Are biases and study limitations identified and discussed? | Yes | |
10. | Is bias due to study's funding or sponsorship unlikely? | Yes | |
10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |