Effects of Obesity Treatments on Food Preferences and Metabolism: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Obesity Treatments on Food Preferences and Metabolism (NCT01724060), a registered phase not stated study. The primary outcome is Change in Energy Intake From Baseline.

2. Clinical Question

The study’s broader stated purpose was to examine how obesity treatments relate to food preferences and aspects of metabolism, including gut hormones, bile acids, and hepatic glucose output. The listed secondary outcomes concern appetite ratings, metabolites, hepatic insulin resistance, and macronutrient composition. These aims describe the questions the study set out to investigate; they do not establish that outcome findings were posted.

The record lists enrollment of 80 and marks the study completed. It does not report a randomized allocation method. Consequently, the treatment groups should not be read as if they were randomized alternatives in a controlled comparison. Differences between groups, if reported elsewhere, could reflect differences in who received each intervention as well as differences associated with treatment.

3. Trial Design

The registry record describes a completed study of obesity treatments, with enrollment of 80 and Imperial College London as sponsor. The listed start was 2012-09 and primary completion was 2017-10. The record does not describe a randomized allocation method; it explicitly notes that this is not a randomized comparison and that the arms are not a like-for-like control comparison.

Eight groups are described: gastric bypass, gastric banding, sleeve gastrectomy, Endobarrier, Exenatide, Liraglutide, lifestyle intervention, and elective surgery or endoscopy. The first seven are obesity interventions or treatments. The last is described as non-bariatric surgery or an elective diagnostic endoscopy. The record does not establish that these groups were intended as interchangeable treatment options or that any one group was a formal control for all the others.

The primary outcome is change in energy intake from baseline, measured at 12 months and expressed in kcal. It is defined as the difference in total calorie consumption between baseline and 12 months. Four secondary outcomes are listed: change in appetite ratings, metabolites, hepatic insulin resistance, and macronutrient composition from baseline. The record lists five outcome measures in total.

Although the study is marked completed, the registry record does not report numerical primary or secondary outcome findings. It also does not report the analysis methods, participant flow, eligibility details, or whether all enrolled participants contributed data at each time point. The registry record lists no analyses. Completion status therefore should not be mistaken for evidence that numerical results are available in the record.

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.

Before assignment: There were no pre assignments requirements

Only the first 6 of 8 groups are shown.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Patients that had specific obesity interventions.

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.

Population: Patients attending obesity clinic from living in a multinational city such as London.

Only the first 6 of 9 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Change in Energy Intake From Baseline, measured over Change at 12 months.

The primary endpoint is change in energy intake from baseline at 12 months. The record defines it as the difference in total calories consumed between those two assessments and specifies kcal as the unit. It characterizes the measure as a mean of a continuous outcome, with standard deviation as the stated dispersion.

Energy intake is a measure of food consumption. As a continuous measure, it can describe the average change in a group while also allowing the spread of individual measurements to be represented by a standard deviation. In general, measuring change from baseline can describe how a group’s outcome differs over time; it does not by itself establish that an intervention caused that change. In a nonrandomized study, changes may also reflect participant characteristics, other influences over time, or differences in who entered each group.

The endpoint is relevant to the study’s stated interest in food preferences and the effects of obesity treatments. However, the registry record does not provide the mean change, standard deviation, group-specific results, or a comparison estimate. It therefore does not show the direction, magnitude, or precision of the primary endpoint findings. The reasons for selecting this endpoint and its role in any prespecified analysis are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies the primary endpoint as a continuous measure: change in energy intake from baseline at 12 months, in kcal. It specifies a mean and standard deviation as the summary approach. A mean describes the central average in a group; a standard deviation describes how spread out observations are around that average. These are general interpretations of the stated summaries, not evidence that numerical values were reported. No mean, standard deviation, or analysis result for this endpoint appears in the registry record.

What does a change-from-baseline measure describe?

In general, a change score compares a participant’s measurement at a later assessment with that participant’s baseline measurement. A group mean change then summarizes those individual changes. It can describe the direction and average size of change among the participants with measurements, but it does not on its own separate an intervention’s effects from other changes over time. The registry record defines the timing as 12 months but does not report the results or the number of participants with measurements at both time points.

Why does the allocation note matter?

The record states that the study was not a randomized comparison and that its arms are not a like-for-like control comparison. The allocation method is not stated. In general, randomization is used to reduce systematic differences between groups at the start of a study. When allocation is not randomized, groups may differ in ways that are related to both treatment choice and outcomes. Such differences can complicate interpretation of between-group contrasts. The registry record does not report participant-level characteristics, an adjustment strategy, or a statistical model that would allow evaluation of this issue.

The groups also represent different kinds of intervention: surgeries, an endoscopic procedure, medications, a lifestyle program, and elective surgery or endoscopy. The record does not identify a single primary comparison across them. General statistical interpretation requires attention to what groups are being contrasted and whether the analysis matches the study design. No comparison estimate or analysis plan is reported in the registry record.

What can uncertainty measures tell readers?

In general, a confidence interval expresses uncertainty around an estimate under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, while an interval that includes values in different directions may leave the direction of an effect uncertain. A p-value, when reported, relates the observed data to a specified statistical model and null hypothesis; it does not convey the size or practical importance of an effect. Neither confidence intervals nor p-values for the primary endpoint are reported in the registry record, so statistical significance and precision cannot be assessed.

What does dispersion add?

A standard deviation describes variability among individual observations around a mean. It is not the same as the uncertainty in the mean, and it does not show the full shape of the data distribution. General statistical methods may need to account for skewness, outliers, or other features of continuous outcomes. The registry record names standard deviation as the dispersion measure but does not report its value or describe distribution checks or any alternative method.

The record’s sample-size assumptions describe a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. These are assumptions for a planning illustration, not the trial’s design justification or observed power. No numerical planning results or observed effect are reported in the record, and the registry record does not report the trial’s own sample-size justification.

More broadly, the registry record does not report a statistical analysis plan, interim analyses, a model specification, covariate adjustment, or handling of repeated measurements. These omissions mean readers cannot determine which statistical procedures, if any, were used for the registered outcomes. The absence of analysis details should not be filled by assuming a conventional method.

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("Gastric Bypass", "Gastric Banding", "Sleeve Gastrectomy", "Endobarrier", "Exenatide", "Liraglutide")
n   <- c(10, 10, 10, 10, 10, 10)
m   <- c(500, 310, 482, 5, 27, 103)
sp  <- c(55, 76, 69, 105, 92, 74)
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  Gastric Bypass  10  500.000  55.000  460.655  539.345
CARM  Gastric Banding  10  310.000  76.000  255.633  364.367
CARM  Sleeve Gastrectomy  10  482.000  69.000  432.640  531.360
CARM  Endobarrier  10  5.000  105.000  -70.112  80.112
CARM  Exenatide  10  27.000  92.000  -38.813  92.813
CARM  Liraglutide  10  103.000  74.000  50.064  155.936

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome and four secondary outcomes. It does not report how analyses across these outcomes were handled, whether any outcome hierarchy was prespecified, or whether adjustment for multiple testing was planned. In general, testing several outcomes can increase the chance of at least one apparently unusual result under a collection of null hypotheses. Multiplicity methods can address that issue, but the registry record does not identify a method. With no numerical outcome analyses listed, the impact of multiplicity on findings cannot be assessed.

Missing-data procedures are also not reported in the registry record. It does not state how many participants had baseline and 12-month energy-intake measurements, how incomplete observations were treated, or whether any imputation or sensitivity analysis was used. In general, missing observations can affect an estimate when the participants with available data differ from those without measurements. The amount and pattern of missingness, along with the assumptions used to address it, are needed to evaluate that risk.

The analysis population is not described. The registry record does not say whether analyses included all enrolled participants, only those who began or completed an intervention, or another defined population. It also does not report exclusions from analysis or reasons for missing assessments. Enrollment of 80 does not establish the sample size for each outcome analysis.

These reporting gaps limit assessment of both the reliability and the scope of any findings. The record lists no analyses, so it does not support conclusions about multiplicity, missing-data handling, or analysis populations beyond noting that these details are not reported in the registry record.

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 safety entries list 10 people at risk in each of the eight groups. For every listed group, the record reports zero serious adverse events, zero other adverse events, and zero deaths. These are the registry’s posted counts for the listed groups.

Zero recorded events should be read as a report of what appears in these entries, not as proof that no adverse events occurred. The registry record does not report the safety observation period, event definitions, collection procedures, or completeness of safety follow-up. It also does not provide event descriptions because no top serious-event terms are listed.

The entries are group-specific and should not be treated as a randomized safety comparison. The record states that the arms are not a like-for-like control comparison. The safety figures also do not establish that risks are equal across treatments or that rare events could be ruled out. General interpretation of safety counts depends on how events were defined and collected, the duration of observation, and the number of participants followed. Those details are not reported in the registry record.

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

The registry record establishes that a completed study enrolled 80 participants and was designed to examine energy intake and other outcomes across several obesity-treatment groups. It defines a primary measure of change in energy intake from baseline at 12 months and lists secondary measures concerning appetite ratings, metabolites, hepatic insulin resistance, and macronutrient composition. It does not report numerical findings for these outcomes.

Consequently, the posted record does not show whether average energy intake increased or decreased, how large any change was, how variable the measurements were, or how precisely an estimate was determined. It does not provide a numerical comparison between groups. No conclusion about the direction or magnitude of the primary outcome can be drawn from the outcome definition alone.

The record also does not establish a causal treatment effect. It explicitly notes that the study was not a randomized comparison and that the groups are not a like-for-like control comparison. In general, nonrandomized group differences can reflect participant characteristics or other influences as well as treatment. The record does not report enough analysis detail to assess how such differences were addressed.

The safety entries report zero serious adverse events, zero other adverse events, and zero deaths in each group, with 10 people at risk per group. These figures describe the registry entries; without reported definitions and follow-up details, they do not establish that no events occurred beyond those recorded or that risks are equivalent across groups.

Thus, the registry record is informative about the study’s intended questions, listed groups, and selected outcomes, but it does not supply the numerical outcome evidence needed to assess findings. A completed status is not itself a result, and the listed outcome measures should not be mistaken for observed effects.

14. Why This Trial Matters Statistically

This study’s statistical interest lies in the range of interventions considered and the mix of biological and behavioral outcomes it set out to examine. The groups include surgical procedures, an endoscopic intervention, medications, a lifestyle program, and elective surgery or endoscopy. The outcomes extend beyond energy intake to appetite ratings, metabolites, hepatic insulin resistance, and macronutrient composition. Together, these registered aims concern several dimensions of food intake and metabolism.

That breadth also makes careful interpretation of study design important. The record says the arms are not a like-for-like control comparison and that the study was not randomized. In general, a collection of different treatment groups does not automatically create a controlled comparison. The question answered by a within-group change differs from the question answered by a contrast between treatments, and the latter depends on a clear comparator and suitable analysis.

From a statistical reporting perspective, the primary endpoint is clearly named and timed, but its numerical results are not reported in the registry record. Without estimates and uncertainty measures, readers cannot evaluate effect size, variability, or precision. The same limitation applies to the listed secondary outcomes. The record also does not describe multiplicity handling, missing-data methods, analysis populations, or the statistical analysis plan.

The safety entries give group-specific counts, but their interpretation is constrained by unreported event definitions and follow-up details. Overall, the record illustrates why design descriptions, outcome definitions, and posted numerical results serve different purposes: the first two explain what a study set out to do, while the results are needed to assess what the data show.

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.

The main limitation for interpreting the registered outcomes is that numerical results are not reported in the registry record. The primary endpoint is defined, but the record provides no mean change, standard deviation, comparison estimate, or uncertainty measure. The listed secondary outcomes likewise have no numerical findings. The record lists no analyses.

The study is explicitly described as nonrandomized, with arms that are not a like-for-like control comparison. The allocation method is not stated. The listed groups involve different procedures, medications, and a lifestyle intervention, so the record does not establish a common comparator for all treatment questions. Participant characteristics and methods for addressing differences between groups are not reported.

Other design and analysis details are also absent. Eligibility criteria, participant flow, outcome-specific numbers analyzed, missing-data procedures, analysis populations, statistical models, multiplicity handling, and a statistical analysis plan are not reported in the registry record. The record does not state whether measurements were available at both baseline and 12 months for all participants.

The safety entries report zero serious adverse events, zero other adverse events, and zero deaths in each group, with 10 at risk in each. However, safety definitions, collection methods, and observation duration are not reported. These omissions constrain interpretation of the event counts.

The record’s completed status and enrollment figure do not resolve these limitations. They describe the study’s status and enrolled population, not the available outcome evidence or the analytic sample for any particular measure.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Effects of Obesity Treatments on Food Preferences and Metabolism — NCT01724060.
• Registry record last updated 2020-03-31; status last verified 2020-03.
• Results first posted 2020-03-31.
• 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

NCT01724060, sponsored by Imperial College London, is listed as completed, with enrollment of 80. The registry record lists a start of 2012-09 and primary completion of 2017-10.

The study concerns obesity and type 2 diabetes mellitus and includes eight groups spanning surgical, endoscopic, medication, lifestyle, and elective-procedure descriptions. The primary outcome is change in energy intake from baseline at 12 months, measured in kcal. Four secondary outcomes concern appetite ratings, metabolites, hepatic insulin resistance, and macronutrient composition.

The record states that the study was not a randomized comparison and that its arms are not a like-for-like control comparison. It lists no analyses and does not report numerical outcome results. Safety entries report zero serious adverse events, zero other adverse events, and zero deaths for each group, with 10 people at risk in each.