EAL

PWM: Prescribed Diet Plan and Nutrition Education (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare the influence of weight-reducing diets containing different amounts of protein and carbohydrates on body composition in obese adolescents.
To examine dietary and physical activity behaviours during follow-up.

Inclusion Criteria:

BMI >97th percentile of the French reference values
11 and 16 years,
no pathologies contributing to obesity
no use of regular medication

Exclusion Criteria:

Not Specified

Description of Study Protocol:

Recruitment

The participants lived for one school year in a medical center (which was also a boarding school) specializing in the treatment of obese children.

Design

Group membership based on diet:

Two groups of students randomized to different diets:

Group 1: PROT- diet was 15% protein (65 g/day on initial diet) and 54% carbohydrates.

Group 2: PROT+ diet was 19% protein (85 g/day) and 50% carbohydrates

Blinding used (if applicable)

Not described

Intervention (if applicable)

Diet:

For both groups energy intake was restricted to 1750 kcal/day until goal body weight was reached. After that, daily energy intake was increased in 1-week steps, to approximately 2200 kcal/day on average (depending on age and sex). The maintenance diet was then followed for 4 weeks. Fat content was identical in both diets (31%).

The percentage of energy ingested over the four daily eating occasions was 20% at breakfast, 31% at lunch, 16% at the afternoon snack and 33% at dinner. Outside snacking was very occasional in the center.

The children and their parents were advised to maintain the same level of energy and nutrient intakes after leaving the center.

Physical Activity:

7 hours/week of vigorous sports (swimming, tennis, handball, aerobic)
7 hours/week of outdoor activities (such as walking or playing)
Television was not available in the center

Parents were advised to maintain the same nutritional intake and physical activity at home during weekends and holidays.

Statistical Analysis

Analysis of variance (ANOVA) test was used to determine differences in physical and behavioral variables between the two diet groups.
ANOVA test for repeated measures were used to compare BMI z-score changes over time between the two dietary groups.
X² test was used for qualitative data tests.
A P-value <0.05 was considered statistically significant.

Data Collection Summary:

Timing of Measurements

Measurements taken at 5 points:

Beginning of study
2 weeks
When the body weight goal determined by the physician was reached (P3) and at the end of the stabilisation phase
1-year follow-up (anthropometric measurements, nutritional intakes and physical activity were recorded at home)
2 years after treatment

Weight program began in September 1997. Follow-up ended in August 2002.

Dependent Variables

BMI and BMI z-scores (computed on the basis of the French reference data)
Body composition (Bioelectrical impedance (BIA) was measured using a two electrode portable impedance instrument)
Dietary behavior (using diet histories)
Physical activity (using questionnaire adapted for French children)

Independent Variables

Diet group: Protein- versus Protein+

Control Variables

Sex, time period from treatment

Description of Actual Data Sample:

Initial N:

121 eligible children (32 boys, 89 girls):

61 (16 boys,45 girls) were randomly allocated to PROT- group
60 (17 boys, 43 girls) to PROT+ group

Attrition (final N):

22 patients (eight in PROT- and 14 in PROT+) dropped out or were excluded before the end of treatment:

9 left because they were home sick
5 for discipline problems
4 for familial reasons
4 did not follow the prescribed diet

Final N: 99 (Protein- Group: 53; Protein+ Group: 46)

1-year follow-up: n=83

2-year follow-up: n=71

However, complete data was available only for 66 children. 82% of children completed the trial up to the end of treatment and 60% up to the end of follow-up (57% in PROT- and 62% in PROT+). There were no significant dietary group differences in drop-out rates (P=0.31).

Age: 11.2-16 years

Ethnicity: not specified

Anthropometrics (e.g., were groups same or different on important measures)

Location: Paris, France

Summary of Results:

Weight Outcomes

Variables	Protein- group Means (SD)		Protein+ group Means (SD)		Statistical Significance
Variables	Baseline	Post-treatment	Baseline	Post-treatment	Statistical Significance
BMI (kg/m2)	36.1 (4.6)	24.2 (2.6)	36.4 (5.4)	24.0 (2.5)	Post-treatment P=0.72
BMI z-score	4.29 (0.6)	1.74 (0.6)	4.27 (0.7)	1.72 (0.6)	Post-treatment P=0.70
Fat Free Mass (%)	68.0 (3.2)	80.4 (5.0)	67.9 (3.9)	79.9 (5.1)	Post-treatment P=0.70

Baseline to Follow-up:

After treatment mean BMI z-scores increased, reaching 2.57±0.9 at 1-year and 2.87±1.1 at 2-years. No significant difference in BMI z-scores from baseline to 2-years was recorded between the two dietary groups (P=0.47).

The mean BMI decrease between baseline and 2-years was 1.471 z-scores. From baseline to 2 years there were no BMI z-score differences between dietary groups (1.471 in PROT- and 1.371 in PROT+; P=0.86) or between genders (1.371 in boys and 1.471 in girls; P=0.60).

Other Findings

GH assays:

No difference in urinary GH/creatinine was observed between dietary groups at baseline (0.3070.36 pg/ml in PROT- and .2270.23 in PROT+; P=0.45).

Between baseline and goal weight urinary GH significantly increased in PROT- group (0.3070.36 to 0.4470.29; P=0.02), whereas no significant change occurred in PROT+ group (0.2270.23 to 0.2170.27; P=0.92).

Lifestyle variables:

At all time points, no difference was observed between PROT- and PROT+ groups, except, as expected, a higher protein intake in PROT+ than in PROT- group (80±14 vs 91±14 g/day at 1-year; P=0.003 and 80±24 vs 92±18 g/day at 2-years; P=0.03).

For both groups. between the first and second year after treatment:

Energy intake increased by 171 kcal, explained by an increase in fat (+86 kcal) and carbohydrates(+85 kcal), mainly sucrose (+62 kcal).
Expressed as percentages of daily energy consumed, breakfast size decreased and snacking increased.
Physical activity decreased and time watching TV increased.

Author Conclusion:

A higher protein content of the diet did not confer any benefit in the treatment of childhood obesity. Substantial weight loss was obtained with a moderately energy-restricted diet and normal fat content. After weight loss, lean weight

increased in spite of moderate energy intake, together with a drift towards obesity-associated behavioural patterns.

Funding Source:

Industry:

Lesieur, Nestle (France)

Food Company:

Reviewer Comments:

Strengths:

One and two-year follow-up
Nine month treatment

Weaknesses:

No description of support given to families to support initial weight loss.
No description of actual diet intake or physical activity for groups during treatment (the assumption seemed to be that since this was a boarding school there was little opportunity for children to vary from the protocol).
Method of randomization not described
Blinding not indicated
Method of recruitment to program not described
Dropout rate (while relatively low for treatment period) was higher for followup--limiting generalizability

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)	???
	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?		No
	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?	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?	No
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)	No
	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?	No
	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?		???
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	???
	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.)	???
	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?	Yes
	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?	No
	6.6.	Were extra or unplanned treatments described?	No
	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)?	No
	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?	No
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