Time Restricted Eating Pilot - Bariatrics: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Time Restricted Eating Pilot - Bariatrics (NCT04006366), a na na study. The primary outcome is Weight.

2. Clinical Question

The trial summary also describes caloric and macronutrient intake and psychosocial measures, including sleep, physical activity, blood pressure, and eating behaviors, as secondary areas of interest. Systolic and diastolic blood pressure are listed as secondary outcomes. These aims describe what the pilot sought to assess; they do not establish that each measure was collected or analyzed, nor do they provide results. The registry record is therefore useful for identifying the study question and intervention structure, but it does not provide enough outcome data to judge the size or precision of weight change.

3. Trial Design

This completed study was a single-group behavioral pilot sponsored by the University of Pennsylvania. Its intervention was time-restricted feeding, described in the trial summary as a 10-hour eating window over 12 weeks. The planned contact pattern was weekly sessions for 4 weeks, followed by a session every two weeks through 12 weeks. The primary outcome was weight change from baseline to 12 weeks.

The registry lists the phase as NA, allocation as NA, masking as none, and the model as single group. These entries indicate that the record does not describe a randomized, masked, parallel-group comparison. There is no recorded control arm against which to separate changes associated with the intervention from changes that could occur over time for other reasons. The intervention group is the only group described in the adverse-event record.

The record gives an enrollment of six. It states that five participants completed the trial and that five participants with more than one data point were included to calculate weight change. The primary-outcome description separately refers to 10 patients who had undergone bariatric surgery and completed the pilot. The record does not explain the mismatch between that description and the enrollment and completion figures. It also does not report how participants were recruited, the eligibility criteria, or what happened to the participant who did not complete the trial.

The study start is recorded as 2019-06-25, primary completion as 2019-11-30, and status as completed. The available record identifies the study design and broad measurement period, but a detailed protocol or statistical analysis plan is not reported in the registry record. In particular, reasons for the single-group design, the sample-size justification, and any planned interim analyses are not reported.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Six participants enrolled, and 5 completed the trial. We included 5 participants who had more than one data point to calculate weight change.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Weight, measured over baseline to 12 weeks.

The primary endpoint is weight, measured in kilograms, with change assessed from baseline to 12 weeks. The registry describes the outcome as a mean, with standard deviation as the measure of dispersion. Weight is a continuous measure, so a mean change can express the average direction and magnitude of change across the analyzed participants. The standard deviation describes how much individual measurements vary around that average; it is not itself a measure of uncertainty in the estimated mean.

Weight was selected as the primary outcome in the trial description because the pilot aimed to assess weight change among post-bariatric surgery patients. The summary notes that weight loss, maintenance, and regain can vary in this population. That context explains the outcome’s relevance to the study question, but it does not establish a clinical threshold for meaningful change. No such threshold is reported in the registry record.

The record says five participants who had more than one data point were included to calculate weight change. It does not provide the baseline and follow-up measurements, the mean change, the standard deviation, or a confidence interval. Consequently, the direction, size, and precision of the primary outcome cannot be determined from the posted results described in the record. The outcome description’s reference to 10 patients also differs from the recorded enrollment of six and completion of five; the reason is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measure, and the registry describes it as mean weight change in kilograms from baseline to 12 weeks. General explanation: a mean is an average that combines individual observations into a single summary. It can be useful for describing the group’s overall change, but it does not show whether every participant changed in the same direction or by a similar amount. Individual-level values would be needed to understand the distribution of changes in detail.

What does the standard deviation describe?

The registry specifies standard deviation as the dispersion measure for the primary outcome. General explanation: standard deviation describes the spread of participant values around their mean. A larger spread indicates more variation among the recorded values, while a smaller spread indicates that values are closer to the mean. It is not the same as a confidence interval and does not, by itself, indicate how precisely the group mean has been estimated. The registry record does not provide the standard deviation for weight change, so that spread cannot be assessed.

How would a confidence interval help?

General explanation: a confidence interval gives a range of values compatible with an estimate under a specified statistical procedure. Its width conveys precision: a wider interval reflects greater uncertainty, while a narrower interval reflects greater precision. A confidence interval would complement a mean change by showing the uncertainty around that estimated average. No confidence interval for weight change is reported in the registry record. Without the estimate and its uncertainty, the reported endpoint definition alone cannot establish how large or precise the change was.

What can a single-group change estimate establish?

The recorded design is single group, and no control arm is described. General explanation: measuring a group before and after an intervention can describe change over the measurement period. A before-and-after change does not automatically isolate the effect of the intervention, because time-related changes and other influences are not separated by a concurrent control comparison. This distinction concerns what the design can support, not whether an individual participant’s measurements changed. The registry does not report an analysis that resolves this limitation.

The record says that five participants with more than one data point were included in calculating weight change. It also gives six enrolled participants and five completers. The primary-outcome description refers to 10 patients, which is inconsistent with those counts as recorded; the reason is not reported. The record does not explain whether weight change was calculated from paired measurements for each participant, how the measurement times were selected when more than one follow-up data point existed, or how incomplete follow-up was handled. Those details matter because choices about which observations contribute can affect the estimate.

What statistical testing is documented?

The registry record lists zero analyses. It does not report a statistical test, a p-value, a confidence interval, an adjusted model, or a prespecified decision threshold for the primary outcome. A statistical test, in general, compares observed data with a defined reference model to assess how compatible the data are with a specified null hypothesis. A p-value, when reported, reflects compatibility under that model; it is not the probability that an intervention is effective, nor a measure of effect size. Since neither a test nor a p-value is reported, there is no posted inferential result to interpret.

The registry also does not report the distributional assumptions used for the primary outcome analysis, any treatment of outliers, or any adjustment for baseline values. General explanation: modeling choices should be matched to the outcome and study design, and their assumptions should be made clear. For example, unusually variable observations can affect summaries and model estimates. Over-dispersion is a general concern when the observed variability is greater than a model’s assumed variability; in that situation, standard errors and inferential conclusions can be unreliable if the model does not account for the extra spread. The record does not report whether this issue was assessed, and there is no basis to infer which model was used.

How should the planning calculations be read?

The record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. These assumptions describe hypothetical planning exercises, not the single-group design itself. The registry record does not report the trial’s own sample-size justification. Any planning sample size should be read as an illustration of assumptions about a future comparison, not as observed power and not as evidence that the pilot had adequate or inadequate power. The numerical planning results are not reported in the registry record.

General explanation: planning calculations depend on the effect targeted, variability, significance threshold, allocation, and statistical method. Changing an assumption can change the required sample size. Calculations based on an observed effect can also be especially uncertain when the underlying pilot is small. They cannot establish what the trial actually found, and they cannot replace transparent reporting of the outcome estimate, variability, and analysis population. Those primary outcome results are not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Intervention")
n   <- c(5)
m   <- c(-0.07)
sp  <- c(1.53)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Intervention  5  -0.070  1.530  -1.970  1.830

11. Multiplicity, Missing Data and Analysis Populations

The registry describes weight as the primary outcome and identifies secondary areas of interest, including caloric and macronutrient intake, psychosocial measures, and blood pressure. Systolic and diastolic blood pressure are listed as secondary outcomes. The record does not provide a complete outcome analysis plan, a hierarchy among secondary outcomes, or a multiplicity adjustment. It is therefore not reported in the registry record whether the investigators planned to control the increased chance of false-positive findings that can arise when many outcomes or comparisons are assessed. No numerical secondary results or inferential tests are reported.

The record reports six participants enrolled, five who completed the trial, and five participants with more than one data point included in calculating weight change. It does not describe how the participant who did not complete the trial was handled, why the other participant is not included in the stated weight-change calculation, or whether any other observations were missing. The primary-outcome description’s reference to 10 patients is also unexplained. These gaps prevent a full assessment of the analysis population and the influence of missing data.

General explanation: missing-data methods can affect which participants contribute to an estimate and the assumptions needed to interpret that estimate. A complete-case analysis, for example, uses only participants with the required measurements; other approaches make different assumptions and require clear reporting. The registry record does not specify which approach was used beyond stating that five participants with more than one data point were included. It does not report imputation, sensitivity analyses, or rules for selecting follow-up observations.

The record lists no analyses. The statistical analysis plan, multiplicity strategy, and details of analysis populations are not reported in the registry record. These absences limit reproducibility and make it difficult to determine whether the posted outcome description reflects all planned analyses.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists six participants at risk in the intervention group. It reports zero serious adverse events, zero other adverse events, and zero deaths. No serious adverse-event terms are listed. These figures describe the recorded event counts for the group; they do not provide a comparison with another group, because the study is recorded as single group.

General explanation: an observed count of zero means that no events of that category were recorded among the participants represented in the safety record. It does not establish that an event is impossible or that the intervention has no safety risks. In a small pilot, the number of observations is limited, and the record does not provide a precision estimate for event rates. No inference about comparative safety can be made without a suitable comparator and fuller safety reporting.

The registry record does not describe the duration or completeness of safety follow-up, how adverse events were solicited, or the criteria used to classify serious events. It also does not give event narratives or participant-level exposure information. The figures should therefore be read as the posted counts, not as a comprehensive assessment of safety or a basis for clinical advice.

13. What the Result Does, and Does Not, Mean

The record establishes that a completed pilot assessed a 10-hour time-restricted eating intervention in post-bariatric surgery patients, with weight change from baseline to 12 weeks designated as the primary outcome. It also records six enrolled participants and five trial completers. These details describe the intervention, study structure, and participant flow as recorded; they do not establish the direction or magnitude of weight change.

The numerical primary-outcome result is not reported in the registry record. Neither a mean change nor its standard deviation or confidence interval is available. As a result, readers cannot assess how much weight changed on average, how variable participants’ changes were, or how precise an estimated average might be. The secondary outcomes are also not accompanied by numerical results in the registry record.

The single-group design places an additional boundary on interpretation. General explanation: an observed change within a group over time does not identify what would have happened to those participants over the same period without the intervention. With no recorded control group, the study does not provide a direct estimate of a between-group treatment difference. This limitation does not negate the value of documenting a pilot, but it means that the study design cannot distinguish the intervention from other possible influences on change.

The enrollment was six, and the record says five participants completed the trial and five participants with more than one data point contributed to the weight-change calculation. The outcome description’s reference to 10 patients is not reconciled with those figures. The registry record also does not report a statistical analysis plan, inferential results, or missing-data procedures. These omissions constrain assessment of both the result and its robustness.

The posted information therefore supports a description of the research question and recorded design, but not a conclusion that the intervention did or did not produce a particular effect. It also does not establish a causal effect, generalizability beyond the studied participants, or a safety profile. Those interpretations would require outcome and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between a study question and a reported result. The registry identifies weight change from baseline to 12 weeks as the primary endpoint and describes the summary measure, but the numerical estimate and its variability are not reported. Knowing the endpoint definition is not enough to judge the observed change or its precision.

The design also illustrates how the comparison structure determines the question that can be answered. A single-group study can describe change over time among participants, but it does not provide a concurrent control comparison. General explanation: a causal treatment contrast requires a defensible comparison of outcomes under different conditions. Without that comparison, changes over time cannot be attributed to the intervention from the design alone.

The participant counts highlight the importance of clear reporting. The record reports six enrolled participants, five completers, and five participants included in calculating weight change, while the primary-outcome description refers to 10 patients. The reason for this difference is not reported in the registry record. Clear reconciliation of these counts, along with the analysis population and missing-data approach, would help readers understand exactly whose observations contribute to the primary estimate.

The trial is described as a pilot, and its sample-size assumptions concern planning illustrations based on the observed effect. General explanation: planning illustrations are conditional on their assumptions and are not substitutes for observed results or estimates of precision. This distinction matters particularly in a small study, where observed effects may be uncertain. The record does not report the trial’s own sample-size justification or numerical primary outcome, so neither adequacy of planning nor outcome precision can be evaluated from the posted results.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations are specific to the information recorded for this trial. First, the study is listed as single group, with no control arm or randomized comparison. Any within-group weight change would therefore be descriptive rather than a direct comparison with an alternative condition. The registry record does not report an approach to address this design limitation.

Second, the participant counts are difficult to reconcile. The record reports six enrolled participants and five trial completers, and says five participants with more than one data point were used to calculate weight change. The primary-outcome description instead refers to 10 patients who completed the pilot. The record does not explain the difference or identify which count should apply to the outcome description.

Third, the primary result itself is not reported numerically. The mean weight change, standard deviation, confidence interval, and inferential result are absent. The registry also does not provide participant-level measurements or enough detail to assess the spread and pattern of change. Secondary-outcome results are not reported either.

Fourth, the analysis methods are not described in enough detail for independent evaluation. The statistical analysis plan, missing-data rules, outcome-measurement procedures, multiplicity approach, and analysis populations are not reported in the registry record. Although five participants with more than one data point are identified for the weight-change calculation, the record does not explain how repeated observations or incomplete follow-up were handled.

Finally, the available safety counts report no events in the recorded categories, but details of safety monitoring and follow-up are not reported. Together, these limitations mean that the record offers a concise account of the pilot’s intent and design, while leaving the observed outcomes and their statistical uncertainty unresolved.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Time Restricted Eating Pilot - Bariatrics — NCT04006366.
• Registry record last updated 2020-07-17; status last verified 2020-07.
• Results first posted 2020-07-17.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes a completed, single-group behavioral pilot of time-restricted feeding among post-bariatric surgery patients. The intervention was a 10-hour time-restricted eating approach over 12 weeks, with weekly sessions for 4 weeks followed by a session every two weeks through 12 weeks. Weight change from baseline to 12 weeks was the primary outcome.

Six participants enrolled, five completed the trial, and five participants with more than one data point were included in calculating weight change. The primary-outcome description separately refers to 10 patients; the record does not explain this difference. The numerical weight-change estimate and its variability are not reported in the registry record. Systolic and diastolic blood pressure are listed as secondary outcomes, but numerical secondary results are not reported.

The adverse-event record lists six participants at risk, with zero serious adverse events, zero other adverse events, and zero deaths. No analysis records are listed. The record does not report the statistical analysis plan, missing-data methods, or sample-size justification.