Effects of Fast Bar on Physiological Fasting: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Fast Bar on Physiological Fasting (NCT04499599), a randomized na study. The primary outcome is Ketone Area Under the Curve.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, controlled, parallel-arm study of Fast Bar and physiological fasting. It lists the study as completed, with a start date of 2020-07-20 and primary completion date of 2020-09-28. The phase is listed as NA. The listed sponsor is L-Nutra Inc. The registry reports enrollment of 110.

Participants were assigned to the Fast Group, Breakfast Group, or Fast Bar Group. Each group has a posted outcome sample size of 35. All groups were asked to consume a standardized ready-to-eat dinner meal before 5 pm on day 1. The Fast Group then fasted overnight for approximately 19 hours. The Breakfast and Fast Bar Groups fasted overnight for approximately 15 hours before consuming the named food on day 2. This design contrasts the Fast Bar condition with a longer fast and includes a breakfast condition with the shorter fasting period.

The registry's masking field identifies the study as double-masked, while the official title describes it as single-blinded. The record does not clarify this difference in wording, nor does it identify which participants or study personnel were masked. The record describes randomized allocation and a parallel model; further details of sequence generation, allocation concealment, adherence assessment, or departures from assigned conditions are not reported in the registry record.

The primary outcome is ketone area under the curve. Two outcome measures are listed, but no secondary outcome results are posted. The registry record does not report the original sample-size justification, the original statistical analysis plan, or whether interim analyses were planned or conducted.

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

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 Ketone Area Under the Curve, measured over BHB Area Under the Curve between 0 to 4 hours after consuming the study foods.

The primary endpoint is blood ketone area under the curve (AUC), reported as a mean in mg/dL*h with standard deviation. The registry identifies the measured substance as ß-hydroxybutyrate (BHB) and specifies an AUC between 0 to 4 hours after consuming the study foods. BHB is measured using an Abbott Precision Xtra Blood Glucose and Ketone Monitoring Meter Kit at 0, 1, 2, 3, and 4 hours after consuming the study foods.

In general, an area under the curve combines measurements over a stated time interval into a summary of the measured quantity across that interval. It can reflect both the level of a measurement and how it changes over time, rather than relying on a single measurement. Here, the AUC provides a continuous outcome for comparing the recorded ketone response across the assigned conditions. The mean describes the group average, while the standard deviation describes the spread of individual measurements around that average.

The record does not report how the time-zero measurement was defined for the Fast Group, which did not consume a study food after its longer fast. It also does not report a threshold for a clinically important AUC difference. Those omissions limit interpretation of the endpoint's practical meaning, even when the measured group differences are statistically distinguishable.

7. Results Posted in the Registry

• Breakfast Group: mean 0.62 versus 1.27 on control; difference -0.65 (95% CI -0.84 to -0.46), standardized effect d = -1.64; z-test p = <0.001.
• Fast Bar Group: mean 1.17 versus 1.27 on control; difference -0.10 (95% CI -0.31 to 0.11), standardized effect d = -0.22; z-test p = 0.347.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous, and the record summarizes it with a mean and standard deviation for each group. In general, the mean is the arithmetic average of the measurements, while the standard deviation describes how dispersed those measurements are around the mean. A smaller standard deviation indicates less spread in the observed values; a larger one indicates more spread. These summaries do not show the full distribution, including whether measurements are skewed or contain outliers.

The comparison estimates are mean differences against the Fast Group. A negative estimate indicates that the named comparison group's mean is lower than the Fast Group's mean under the coding used for the posted comparison. For Breakfast Group versus Fast Group, the estimate is -0.65 mg/dL*h. For Fast Bar Group versus Fast Group, the estimate is -0.1 mg/dL*h. Both are unadjusted comparisons; the registry record does not report covariate adjustment or a model specification for the trial's own analysis.

A confidence interval expresses a range of estimates compatible with the data and the method used to calculate the interval. It helps convey uncertainty around a point estimate; it is not a range containing a known proportion of individual participant outcomes. The confidence interval for Breakfast Group versus Fast Group is entirely below zero, while the interval for Fast Bar Group versus Fast Group spans zero. The confidence level and the method used to form the registry's intervals are not reported in the registry record.

A p-value describes how unusual a result at least as extreme as the observed result would be under a specified null hypothesis and the assumptions of the test. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. The unadjusted p-value for the Breakfast comparison is <0.001; for the Fast Bar comparison it is 0.347. The registry record does not report the trial's prespecified significance threshold or its testing procedure. The planning illustrations separately specify a two-sided significance level of 0.05; that assumption belongs to those illustrations and should not be treated as a reported trial analysis plan.

In general, variability affects how precisely a group mean and a difference between group means can be estimated. More variability makes it harder to distinguish a group difference from random variation when other design features are held constant. The posted standard deviations differ across the groups, with the Breakfast Group showing a smaller spread than either the Fast Group or Fast Bar Group. A pooled standard deviation is also listed for each comparison, but the registry record does not explain whether or how such a pooled value entered the original trial analysis.

The study is described as randomized and parallel-arm. Random allocation can help balance measured and unmeasured characteristics across groups on average, but it does not guarantee balance in a particular study. The registry record does not report the randomization method, allocation concealment, adherence, crossovers, or whether all randomized participants were included in each outcome analysis. The record also does not report a missing-data method, an intention-to-treat definition, or a per-protocol analysis population.

Multiplicity arises when several outcomes or comparisons are tested, because conducting multiple tests can increase the chance of at least one apparently unusual result under a collection of null hypotheses. The registry lists two outcome measures and posts no secondary outcome results. It also contains comparisons against the Fast Group for both food conditions. A multiplicity adjustment plan, hierarchy of tests, or distinction between confirmatory and exploratory comparisons is not reported in the registry record. The p-values should therefore be read as unadjusted rather than as evidence that a multiplicity strategy was applied.

The planning illustrations use a normal approximation, equal allocation between the two arms, and a two-sided significance level of 0.05. They use the observed effect as a reference and consider effects stated as 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. These are planning assumptions, not reported features of the trial's original design. The registry record does not report the original sample-size justification or its assumptions. In general, the adequacy of a statistical method also depends on how well its assumptions fit the data; the registry record does not report diagnostic checks or alternative analyses.

10. Confidence Intervals and Precision

The posted estimates differ in precision. For Breakfast Group versus Fast Group, the mean difference is -0.65 mg/dL*h, and its confidence interval lies entirely below zero. This indicates that the interval of estimates compatible with the reported comparison does not include no mean difference. The unadjusted p-value is <0.001. The exact confidence limits are not repeated; the confidence level and interval method are not reported in the registry record.

For Fast Bar Group versus Fast Group, the mean difference is -0.1 mg/dL*h, and its confidence interval includes values below and above zero. This interval is compatible with a negative difference, no difference, and a positive difference under the interval method. The unadjusted p-value is 0.347. The estimate is therefore not sufficiently precise to distinguish the observed contrast from zero using that comparison's reported inferential result. That does not show that the groups are equivalent; an equivalence margin and an equivalence analysis are not reported in the registry record.

In general, a confidence interval communicates uncertainty in an estimate, while a p-value alone does not show the range of plausible effect sizes. Neither one establishes whether a difference matters in practice. The registry record does not give a threshold for a clinically meaningful difference in ketone AUC, and it does not report the confidence level. Interpretation should also account for the study context: the Fast Bar and Fast Groups had different overnight fasting durations, and the record does not provide a direct comparison of Fast Bar with the Breakfast Group.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrations calculated from the observed effect, rather than the trial's own sample-size justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set at the stated fraction of the observed effect. The original trial's design assumptions are not reported in the registry record.

The 80% power column gives the illustrative number of participants per arm for a design with an 80% chance of detecting the specified effect under those assumptions, if that effect and the assumptions were true. The 90% power column gives the corresponding planning number for a 90% chance. These are design calculations, not observed results or evidence that the completed study had a particular probability of success.

For the Breakfast Group comparison, planning for 100% of the observed effect gives 6 participants per arm for 80% power and 8 participants per arm for 90% power. For the Fast Bar Group comparison, planning for 100% of the observed effect gives 312 participants per arm for 80% power and 417 participants per arm for 90% power. These markedly different illustrations reflect the different observed effect sizes relative to variability in the comparisons; they are not replacements for a prospectively justified design.

For either comparison, planning for a smaller fraction of the observed effect requires more participants per arm. For example, the stated 75% and 50% effect scenarios require larger planning counts than the 100% scenario. These calculations are not observed power. Their values depend on the observed effects and the listed simplifying assumptions, and the registry record does not report assumptions about attrition, missing outcomes, or any adjustment for multiple comparisons.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -0.650; pooled standard deviation σ = 0.396.
2. n = 2 × (1.96 + 0.842)² × 0.396² / -0.650² = 5.8, rounded up to 6 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -0.65                      # observed difference in means
sigma <- 0.395790348543266                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(4499599)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 6 (80% power), 8 (90% power)
 75% of observed effect: n per arm = 11 (80% power), 14 (90% power)
 50% of observed effect: n per arm = 24 (80% power), 32 (90% power)
power.t.test: 6.9 
Simulated power at n = 6 per arm: 0.730 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a multiplicity strategy for the outcome measures or pairwise comparisons. It lists two outcome measures and posts no secondary outcome results. The posted comparisons address the Breakfast Group and Fast Bar Group relative to the Fast Group. Whether these were prespecified as primary contrasts, whether other comparisons were planned, or whether a correction or hierarchical testing procedure was used is not reported in the registry record. The p-values are unadjusted.

Missing-data handling is also not reported in the registry record. Although the outcome summaries list 35 participants in each group, the record does not state whether these were all randomized participants, all participants with measurements, or a defined analysis population. The registry does not report the number of missing endpoint measurements, reasons for missingness, imputation, or sensitivity analyses. No assumption about complete follow-up or missing-data mechanisms can be made from the posted summaries alone.

The registry record does not specify whether the primary analysis was intention-to-treat, per-protocol, or based on another population definition. It does not report how protocol deviations, nonadherence, or withdrawals were handled. It also reports no analysis entries and no secondary outcome results. These omissions limit assessment of whether the posted estimates represent a prespecified primary analysis and how robust they are to analytic choices.

In general, multiplicity and missingness can affect uncertainty and interpretation. Adjusting for multiple testing may alter inferential thresholds, while handling missing measurements differently may alter estimated group means. Without the analysis plan and participant flow details, the registry summaries cannot resolve these issues. This uncertainty does not negate the recorded estimates, but it limits the strength of conclusions drawn from them.

14. 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 registry reports serious adverse events for each group, with 35 participants at risk in each group and 0 serious adverse events in each. It also reports 0 other adverse events in each group, with 35 participants at risk in each, and 0 deaths in each group. No serious adverse event terms are listed.

These are the adverse-event figures recorded in the registry. A recorded count of zero means no events of that category were reported for the listed groups; it does not establish that no event occurred outside the reporting or observation process, or that an intervention carries no risk. The record does not provide further detail on event collection, follow-up duration for safety, event definitions, or whether all participants completed safety follow-up. The figures should therefore be interpreted as registry-reported counts, not as proof of absence of risk.

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

The posted results describe measured ketone AUC after the study's assigned fasting and food conditions. The Breakfast Group had a lower reported mean than the Fast Group, with an unadjusted mean difference of -0.65 mg/dL*h, a confidence interval lying below zero, and p < 0.001. The Fast Bar Group's mean was closer to the Fast Group's reported mean; its unadjusted difference was -0.1 mg/dL*h, its interval included zero, and p = 0.347. These are statistical descriptions of the registry results, not treatment recommendations.

The Fast Bar comparison does not isolate the effect of consuming a Fast Bar from the difference in fasting duration. The Fast Bar Group followed an approximately 15-hour overnight fast, while the Fast Group fasted for approximately 19 hours. The Breakfast Group also followed approximately 15 hours of fasting before consuming a breakfast bar, but a direct comparison between the two food groups is not posted. The results therefore do not establish how the two bars compare with each other.

A p-value above a conventional threshold does not demonstrate equality, and a confidence interval spanning zero does not rule out potentially meaningful differences. Conversely, a small p-value does not show that a difference is important in practice. The registry record gives no threshold for clinical importance, and the confidence level and statistical analysis plan are not reported. The reported precision and limitations should be considered alongside the point estimates.

The findings do not establish effects in populations or settings beyond those represented in this study, and the registry does not supply enough population detail to assess broader applicability. The record also does not report missing-data procedures or analysis populations. The results are best understood as the posted group-level outcome summaries and unadjusted comparisons under the recorded study conditions, rather than as a definitive statement about clinical benefit or harm.

16. Why This Trial Matters Statistically

This study illustrates why the size of a mean difference must be read alongside its uncertainty and the variability of the outcome. The Breakfast Group comparison has an estimate whose confidence interval lies below zero, while the Fast Bar comparison's interval spans zero. Those patterns convey different levels of statistical evidence in the posted comparisons, but neither confidence intervals nor p-values determine whether an effect is practically important.

The two planning illustrations also show how sample-size requirements depend on the effect being targeted relative to variability. Planning for the observed effect in the Breakfast comparison yields much smaller figures than planning for the observed effect in the Fast Bar comparison. As the planning effect is reduced to 75% or 50% of the observed effect, the required participants per arm increase. The figures are not a retrospective assessment of power and do not reveal how the trial's original enrollment target was chosen; that justification is not reported in the registry record.

The design highlights the importance of a clearly defined comparator. The Fast Bar and Fast Groups differed in both food consumption and overnight fasting duration, so their contrast cannot distinguish those components. The separate breakfast condition offers context but does not replace a posted direct comparison between the food groups. For clinical researchers, this distinction matters when translating a group contrast into a question about a specific intervention.

Finally, the record demonstrates why results should be interpreted with information about analysis populations, missing data, multiplicity, and outcome definitions. Those details are not reported in the registry record. Their absence does not change the posted estimates, but it limits how fully readers can evaluate the analysis and the scope of the conclusions.

17. 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 primary comparison of Fast Bar with the Fast Group combines differences in food consumption and fasting duration. The Fast Group fasted for approximately 19 hours, while the Fast Bar Group fasted for approximately 15 hours before consuming the bar. The registry record therefore does not allow the posted comparison to isolate the bar from fasting duration. Although the Breakfast Group had the same stated overnight fasting duration as the Fast Bar Group, a direct comparison between those groups is not posted.

The registry record does not report key population details, a clinically meaningful threshold for ketone AUC, the original sample-size justification, or the statistical analysis plan. It also does not report the method for calculating confidence intervals or their confidence level. The masking description is inconsistent across record text: the registry field identifies double masking, while the official title says single-blinded, and the difference is not clarified.

Information on participant flow, outcome completeness, missing-data handling, adherence, protocol deviations, analysis populations, and covariate adjustment is not reported in the registry record. The record posts no secondary outcome results and does not describe a multiplicity strategy. These omissions make it difficult to assess the extent to which the posted summaries reflect prespecified analyses or how sensitive they might be to other analysis choices. The adverse-event record reports zero events, but further details about safety follow-up and event collection are not reported.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Effects of Fast Bar on Physiological Fasting — NCT04499599.
• Registry record last updated 2024-04-09; status last verified 2024-04.
• Results first posted 2021-10-04.
• 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.

21. Record Summary

The registry describes a completed randomized, controlled, parallel-arm study of Fast Bar and physiological fasting, sponsored by L-Nutra Inc. It reports enrollment of 110, a start date of 2020-07-20, and a primary completion date of 2020-09-28. The primary outcome is blood ß-hydroxybutyrate area under the curve between 0 to 4 hours after consuming the study foods, reported as a mean and standard deviation.

The posted mean AUC was 1.27 mg/dL*h in the Fast Group, 0.62 mg/dL*h in the Breakfast Group, and 1.17 mg/dL*h in the Fast Bar Group. The Breakfast comparison with Fast Group had a mean difference of -0.65 mg/dL*h and p < 0.001; the Fast Bar comparison had a mean difference of -0.1 mg/dL*h and p = 0.347. The registry reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each group. Important analysis details, including missing-data handling and the trial's original sample-size justification, are not reported in the registry record.