EAL

SSPSM: Compliance (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To study the effects of high-protein (HP) vs. high-carbohydrate (HC) diets on various metabolic end points.

Inclusion Criteria:

Age 20 to 50 years
BMI between 30kg/m² and 55kg/m²
Fasting glucose less than 110mg per dL
Two-hour glucose level less than 170mg per dL.

Exclusion Criteria:

Proteinuria or elevated serum creatinine (more than 1.5mg per dL)
Surgical or premature menopause
History of liver disease
Abnormal liver function tests
Diabetes
Thyroid disease with abnormal thyrotropin
Weight more than 350 lbs
Triglycerides higher than 400mg per dL or LDL cholesterol higher than 160mg per dL
Systolic blood pressure higher than 145mm Hg or diastolic blood pressure higher than 100mm Hg
Use of medications known to affect lipid or glucose metabolism (niacin, steroids, and statins)
Pregnancy or the desire to become pregnant in the next six months
Weight loss of more than 5% of body weight in the last six months
History of cancer or undergoing active treatment.

Description of Study Protocol:

Design

Prospective RCT.

Blinding Used

All investigators except for the nutritionist were blinded to the diet assignment.

Intervention

HP diet vs. HC diet with 30% kcal from fat in both groups for a period of six months
Participants were given all food needed to meet their dietary assignment for the duration of the study. Without a metabolic kitchen, fresh, pre-packaged and frozen foods were used.
Most of the entrees for the HP diet were Cedarlane The Zone frozen entrees. They were purchased directly from the manufacturer. Additional entrees were purchased from the Whole Foods Market: Boca Chik’n Nuggets and Whole Foods brand Yellow Fin Tuna Burgers, Alaskan Salmon Burgers and Mahi Mahi Burgers, which were served with a Rudi’s 100% Whole Wheat Organic bun. Snacks in between meals included Slim Fast High Protein Shakes and Zone Perfect bars.
All of the entrees for the HC diet are readily available at most grocery stores. These options included frozen entrees made by Lean Cuisine, Healthy Choice, Smart Ones and Amy’s frozen burritos. Snacks in between meals include Slim Fast Optima Shakes and Slim Fast Meal Bars.
Both diets included one cup of frozen vegetables at both lunch and dinner. Participants chose from broccoli, cauliflower, carrots, green beans, California blend and Brussels sprouts. There were five breakfast choices that are adapted by the use of Canadian bacon, margarine and almonds to adjust for macronutrients such as eggs and toast, cold cereal (Cheerios or Special K Protein Plus) and 2% milk, oatmeal, yogurt, and cottage cheese. Each breakfast included canned peaches, canned mixed fruit or applesauce.

Statistical Analysis

Changes were compared between the two arms using Wilcoxon rank sum test to compare the effects of the two diets. In addition, Wilcoxon signed rank test was used to compare baseline and six-month data to assess effects of each diet. Statistical significance was declared if the two-sided P value was less than 0.01 to account for multiple comparisons.

Data Collection Summary:

Timing of Measurements

Weight was measured weekly during the study.

Dependent Variables

BMI
Percentage of weight loss.

Independent Variables

Provision of HP or HC diet for six months.

Control Variables

Timing of measurements
Calculation of participants' kcal needs
RD feedback and compliance measures.

Description of Actual Data Sample:

Initial N

HP: N=14
HC: N=18.

Attrition (Final N)

HP: N=12
HC: N=12.

Age

HP: 35.9±2.1 years
HC: 35.4±2.0 years

Ethnicity

HP:
- African-American: Seven
- Caucasian: Five.
; HC:
- African American: 10
- Caucasian: Two.

Anthropometrics

No significant differences between groups at baseline.

Location

Memphis, TN, United States.

Summary of Results:

Key Findings

Weight Loss

Variables	Treatment Group Measures and Confidence Intervals	Control Group Measures and Confidence Intervals	Statistical Significance of Group Difference
BMI (kg/m²)
Baseline	41.3±1.8	37.0±1.5	0.5512
Six months	37.3±1.9	33.5±1.4
Percent weight loss (six months)	9.8±1.4	9.3±1.6	0.9323

The weight loss and BMI (as well as FM and LM) were significantly improved at six months from baseline in both the HP and HC diets, but the differences between the two diets were not significant
There were no significant differences in compliance between groups (94±1.5% in HP group, 91±4.8% in the HC group, P=0.3979)
After six months of the HP vs. HC diet (12 in each group), the following changes were significantly different for the following parameters:
- Dichlorofluorescein (-0.8mcgmol vs. -0.3mcgmol per L, P<0.0001)
- Malondialdehyde (-0.4mcgmol vs. -0.2mcgmol per L, P=0.0004)
- C-reactive protein (-2.1mg vs. -0.8mg per L, P=0.0003)
- E-selectin (-8.6ng vs. -3.7ng per ml, P= 0.0007)
- Adiponectin (1,284ng vs. 504ng per ml, P=0.0011)
- Tumor necrosis factor-alpha (-1.8pg vs. -0.9pg ml, P<0.0001)
- IL-6 (-1.3pg vs. -0.4pg per ml, P <0.0001)
- Free fatty acid (-0.12mmol vs. 0.16mmol per L, P=0.0002)
- REE (259kcal vs. 26kcal, P<0.0001)
- Insulin sensitivity (4 vs. 0.9, P<0.0001)
- Beta-cell function (7.4 vs. 2.1, P<0.0001).

Author Conclusion:

To our knowledge, this is the first report on the significant advantages of a six-month hypocaloric HP diet vs. hypocaloric HC diet on markers of beta-cell function, oxidative stress, lipid peroxidation, pro-inflammatory cytokines and adipokines in normal, obese females without diabetes. We were able to demonstrate that reduction of daily kilocalories in both diets, as expected, leads to equal amount of weight loss.

Funding Source:

Government:

Medical Student Research Fellowship from NIH/NIDDK

Not-for-profit

American Diabetes Association

Reviewer Comments:

Only women were studied.
A small numbers of subjects in groups.

Quality Criteria Checklist: Primary Research
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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	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.)	N/A
	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?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	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%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	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?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	Yes
	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.)	Yes
	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?	N/A
	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?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	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?	N/A
	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?	Yes
	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)?	Yes
	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