EAL

AWM: Eating Frequency and Patterns (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the relationships between eating frequency (EF) and body weight status and to determine whether these relationships can be explained in terms of differences in physical activity levels, macronutrient intakes, or energy compensation.

Inclusion Criteria:

BMI between 18 and 30, aged between 20-55, not pregnant or nursing, not suffering from any known disease or disability, and not on any dietary regime.

Exclusion Criteria:

None stated.

Description of Study Protocol:

Recruitment Recruited from 2 large manufacturing companies in Edinburgh and Glasgow.

Design Anthrompometric measures were made on one occasion. Food intake was determined with a 7-day unweighed food diary. Concurrent with food diaries, physical activity was measured. Before analysis, diaries were scrutinized for underreporting.

Blinding used (if applicable) NA

Intervention (if applicable) NA

Statistical Analysis 2-tailed Pearson correlation coefficients.

Data Collection Summary:

Timing of Measurements cross-sectional over 7 days

Dependent Variables

eating frequency - eating occasion was defined as any occasion when food was taken and that was separated from other consumption by > 15 minutes. If < 15 minutes the 2 occasions were considered to be 1. Drinks (excluding milk in excess of 1 cup) consumed in the absence of food were not considered to be eating occasions and do not appear to have been included in the analyses. However, when data was re-analyzed to include meals and snacks, a snack was defined as any food or calorie-containing drink consumed outside of regular mealtimes.

Independent Variables

body weight - without shoes or jacket on portable scales
height - measured on portable stadiometer
BMI body fat - measured at biceps, triceps, sub-scapular, supra-iliac and % BF calculated with Durnin & Womersley method
activity - recorded in 2 minute increments; heart rate was also recorded for 2 days (1 weekday, 1 weekend day) during the same period
energy intake - measured with 7 day unweighed food record
macronutrient intake - measured with 7 day unweighed food record

An Control Variables none

Description of Actual Data Sample:

Initial N: 112 enrolled in the study

Attrition (final N): 17 drop-outs before completion. 95 (48 men, 47 women) completed the study. After data was collected, records from 16 subjects (6 men, 10 women) had a reported intake below the 1.1 cut-off for energy intake:BMR ratio, were judged as under-reporters, and were excluded from the analyses. Final n = 79 (70% of original n).

Age: men = 37.4 +/- 10.4; women = 34+/-8.6

Ethnicity: not reported

Other relevant demographics: none reported

Anthropometrics

weight: men=79.6 +/- 11.7 kg; women=59.3 +/- 8.0

BMI: men=25.3 +/- 3.0; women=22.8 +/- 2.9

Location: U.K.

Summary of Results:

Overall, men and women ate an average of slightly more than 4 meals per day.

For body weight status measures:

Body weight in men (r=-0.3436, P=0.03) was inversely related to EF.
Body weight in women was not related to EF (P=0.41).
There were no significant relationships between BMI and percent BF and EF for men or women, or for body weight and eating.

For dietary intake:

In men, only % CHO (r=0.3036, P<0.05) was related to EF.
In men, EF was not related to energy intake (P=0.60), % fat (P=0.66), % protein (P=0.57), or any other nutrient studied.
In women, energy intake (r=0.4158, P=0.01), % CHO (r=0.3791, P=0.02), grams of CHO (r=0.5429, P=0.001), and grams of sugar (r=0.4170, P=0.01) were positively related to EF.
In women, EF was not related to % fat (P=0.69), % protein (P=0.53), or any other nutrient studied.

For physical activity levels:

In men, time heart rate was 20-40 beats above normal (r=-0.3362, P=0.04) was inversely related to EF.
In women, % TEE in leisure activity (r=0.3332, P=0.047) was related to EF after removal of 1 outlier.

Author Conclusion:

In men, the association between increased EF and lower body weight status may have been influenced by increased physical activity levels. As energy intake did not increase with EF, men appear to have compensated by reducing the mean energy consumed per eating episode. Energy compensation did not take place in women, with women who ate most frequently having the highest energy intakes; although this did not lead to higher BMIs. Physical activity, through participation in active leisure pursuits, may have been an important factor in weight control in women. The % contribution of CHO to total energy was positively correlated with EF in both men and women, and further analysis showed that snack foods provided a higher proportion of CHO than did foods eaten as meals. These results indicate that a high EF is likely to lead to a high CHO diet, which may be favorable for weight control. Our findings suggest that in this population, a high EF was associated with leanness in men, and there was no link between EF and body weight status in women.

Funding Source:

University/Hospital:

Queen Margaret College (UK)

Reviewer Comments:

This was a well done study in many ways, concluding that eating frequency (EF) was related to body weight in men, but not in women. However, it suffers from several shortfalls. First, it did not adequately address the effect of snacking, in particular the contribution of calorie-containg drinks. The authors report their correlations between EF and intake without the inclusion of calorie-containing drinks that were consumed in the absence of food. Although they re-analyzed the data to include those drinks, they only reported how those snacks differed in macronutrient composition from meals and do not provide any details as to how much the addition of those calorie-containing drinks added to energy intake. This information would have been particularly interesting, given that calorie-containing drinks have been hypothesized to be a contributor to excess body weight. The statistical treatment of the data may also have been over-simplified. Pearson correlations provide information only on each separate independent variable and EF and fail to consider how all of the independent variables might work together. Last, although it was not a stated aim of the study, the failure to include obese subjects may have limited the abiity to find associations between EF and body weight. The subjects in this study seemed (ranges were not reported) to all fall within normal or slightly overweight BMIs.

The authors also point out that their definition of meal differed from those used by other authors. Coming to a standard definition of what constitutes a meal might shed more light on how meal patterns impact body weight. Although it might be difficult to come to such a definition, researchers might consider re-analyzing data using the various definitions so that comparisons between studies could be done.

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)	N/A

Validity Questions
1.	Was the research question clearly stated?		???
	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?		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?	N/A
	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?	Yes
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)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	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.)	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?		Yes
	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%.)	Yes
	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?	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?		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?	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?	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?		No
	7.1.	Were primary and secondary endpoints described and relevant to the question?	No
	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?	No
	7.7.	Were the measurements conducted consistently across groups?	N/A
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		No
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	No
	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)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	No
	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