EAL

VN: Therapeutic Vegetarian Diets and Attrition (2009)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The main objective of this study was to determine the prognostic value of psychosocial factors for weight reduction in obese people by analyzing physical and psychosocial functions, mood and eating behavior during diet-induced weight loss in a trial of vegetarian vs. non-vegetarian diets.

Inclusion Criteria:

Moderately obese women with body weight above 80kg were recruited through advertisements in a local newspaper.

Exclusion Criteria:

No exclusion criteria reported.

Description of Study Protocol:

Recruitment

Recruitment was for moderately obese women with body weight above 80kg via advertisements in a local newspaper.

Design

30 pairs, matched for age, height, weight and BMI (all non-vegetarian), accepted randomization to a vegetarian or non-vegetarian diet. Pairs were similar in metabolic profile and sociodemographics. Psychological measures at baseline in the study sample were compared to reference subjects. Every third week, body weight and blood pressure was measured, dietary adherence was checked and additional counseling was offered by a dietitian. Individual and group meetings were used alternately during the two-year study.

Blinding Used

No blinding procedure was reported.

Intervention

Obese women with an average weight of 94kg were randomly assigned either a 1,300 calorie lactovegetarian or 1,300 calorie non-vegetarian diet. Additional individual or group counseling was offered every three weeks by a dietitian.

Statistical Analysis

Significance of group differences (vegetarian vs. non-vegetarians, compliers vs. non-compliers at baseline and after three and eight months) was performed by Fisher's non-parametric permutation test
The magnitude of improvements or deterioration was tested also by Fisher's non-parametric permutation test
To test the relationship between changes in psychological variables and between these and the weight parameters was tested by Pearson correlation
Stepwise multiple regression procedures were conducted to assess the specific relationships between weight change variables and psychological correlates and to calculate the total amount of explained variance.

Data Collection Summary:

Timing of Measurements

Weight parameters were measured at baseline and every three weeks throughout the two years of the study
Psychological questionnaires were administered at baseline, after three and eight months and at the end of the two-year study.

Dependent Variables

Body weight to nearest 0.1kg using calibrated balances (in light clothing without shoes)
Height to nearest 0.01m in standing position without shoes
Body Mass Index (kg/m²)
Waist circumference calculated to nearest 1mm at the level midway between the lower rib margin and the iliac crest
Hip circumference calculated to nearest 1mm at the widest point between hip and buttock
Waist to hip ratio
Mood Adjective Checklist
Sickness Impact Profile (minus two categories with little relevance to the study, i.e. communication and eating)
Three Factor Eating Questionnaire (a valid test to describe human eating behavior in obese dieting subjects).

Independent Variables

1,300 calorie lactovegetarian diet
1,300 calorie non-vegetarian diet.

Control Variables

A group of non-obese women between 23 and 57 years of age were selected for comparison of self-assessed eating behavior
Functional status in the obese was compared to a stratified random sample from a population study of women in Goteborg
Mood scores were compared to a population group of 19- to 70-year-old women.

Description of Actual Data Sample:

Initial N: 60 subjects (30 pairs)
Attrition (final N): 28 subjects
Age: 25 to 65 years old (mean age was 43 years)
Ethnicity: Not specified
Other relevant demographics: Sociodemographics, smoking habits, alcohol consumption, premenopausal status and self-assessment measurements of function, mood and eating behavior before dieting were comparable
Anthropometrics: Mean BMI (baseline) was 33. The two groups of dieters were similar in metabolic profiles.
Location: Sweden.

Summary of Results:

Typical weight loss occurred, i.e. early weight loss after three months of more than 5kg, and weight stability reached at an average of eight months with maximum weight loss then of almost eight kg
No differences between lactovegetarian and non-vegetarian groups at baseline, or in weight loss, time spent in weight stability, duration or amount of relapse, therefore, results from both groups were analyzed together
Completion rate over time in the two year study was about the same in the vegetarian and non-vegetarian groups, however, there were more non-compliers in the vegetarian group early in the program
General mood improvements (P<0.01) were reported during early weight loss with the rise in overall mood related to changes in self-assessed eating behavior (P<0.0001) and weight loss (P<0.05) during the first three months
Mental well-being deteriorated from the time of weight stability to the two-year follow up, with the overall mood score decreased from 3.26 on average at eight months to 3.00 at follow-up (P<0.01)
The proportion of subjects with no reported sickness impact (overall SIP index) rose from 25% at baseline to 46% at the two-year follow up
Long term changes in compliers were consistent with the pattern found at three and eight months, i.e. a substantial increase of restraint eating (P<0.0001), and decreased disinhibition (P<0.001) and hunger (P<0.01), however, a trend towards returning to pretreatment levels can be seen after 24 months of dieting
Subjective prediction of weight loss at three weeks was the best predictor of maximum weight loss (P<0.001) i.e. the more optimistic the greater the weight loss
At study end, disinhibition was the strongest correlate of absolute weight gain (P<0.0001), yet health-related dysfunction was significantly related to weight regained (P<0.01) even when the influence of disinhibition was controlled for.

Author Conclusion:

Long term dieting demonstrates changes in mood during the course of dieting and by early changes in self-assessed eating behavior with a substantial increase in restraint eating and decrease in disinhibition scores. The results of this study indicate that self control (restraint eating and disinhibition) is a clinically useful predictor of weight loss and that mood measures during early weight loss, weight stability and relapse suggest that going on a diet has few adverse consequences. Following a weight-reduction program for two years leads to little long-term weight loss, but is better than not persisting.

Funding Source:

Government:

Swedish Council for Social Research

Reviewer Comments:

Although the author stated this was a trial of weight loss of vegetarian vs. non-vegetarian diets, it was acknowledged as a secondary objective to that of determining the prognostic value of psychosocial factors for weight reduction. Data confirmed that there was no difference in weight loss between vegetarian vs. non-vegetarian dieters, and other than stating this, minimal information regarding vegetarianism was communicated in the research report.

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
	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
	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
	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
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
	1.	Was the research question clearly stated?	Yes
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.1.	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
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
	1.3.	Were the target population and setting specified?	Yes
	2.	Was the selection of study subjects/patients free from bias?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	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
	2.1.	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
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	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
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
	3.	Were study groups comparable?	Yes
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
	3.1.	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
	3.2.	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
	3.3.	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
	3.4.	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
	3.5.	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
	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.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	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
	4.2.	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
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	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
	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.	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
	5.1.	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
	5.2.	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
	5.3.	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
	5.4.	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
	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.	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
	6.1.	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
	6.2.	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
	6.3.	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
	6.4.	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
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments 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
	6.7.	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
	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.	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
	7.1.	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
	7.2.	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
	7.3.	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
	7.4.	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
	7.5.	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
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	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.	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
	8.1.	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
	8.2.	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
	8.3.	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)?	N/A
	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)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	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
	8.6.	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
	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.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	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.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes