Muscle and strength

OVERVIEW + STUDY DETAILS

Follow the evidence.

Start with the finding and its limits.
Open the study details to look closer.

Conceptual consensus

EWGSOP2: sarcopenia definition and assessment

In this analysis, DXA lean mass is fat-free mass minus bone mineral content. It includes tissues other than muscle and, alone, does not describe strength or diagnose sarcopenia.

Under EWGSOP2, low strength indicates probable sarcopenia; low muscle quantity or quality confirms the diagnosis, and low physical performance together with the other criteria identifies severe sarcopenia.

Evidence design: Diagnostic consensus concept

Keep in view

Diagnostic consensus; it does not estimate a treatment effect or individual risk.
A decrease in total DXA lean mass alone does not diagnose sarcopenia.

See study details — EWGSOP2

Definitions and assessment framework

Diagnostic consensus concept

Expert consensus updating the European definition and diagnostic approach to sarcopenia; not an intervention trial.

Diagnostic concepts

Diagnostic state
Probable sarcopenia
Definition
Low muscle strength identifies probable sarcopenia.
Diagnostic state
Confirmed sarcopenia
Definition
Low muscle quantity or quality confirms the diagnosis in the presence of low strength.
Diagnostic state
Severe sarcopenia
Definition
Low strength, low muscle quantity/quality and low physical performance together identify severe sarcopenia.

Assessment sequence

Find cases
Assess muscle strength
Confirm muscle quantity or quality
Determine severity with physical performance

What the curated evidence supports

In this analysis, DXA lean mass is fat-free mass minus bone mineral content. It includes tissues other than muscle and, alone, does not describe strength or diagnose sarcopenia.
Under EWGSOP2, low strength indicates probable sarcopenia; low muscle quantity or quality confirms the diagnosis, and low physical performance together with the other criteria identifies severe sarcopenia.

Limitations

Diagnostic consensus; it does not estimate a treatment effect or individual risk.
A decrease in total DXA lean mass alone does not diagnose sarcopenia.

Verification scope

Verified through 2026-11-04 within the consulted scope.

Bibliographic metadata checked: Yes
Original article abstract consulted: Yes
Full-text consultation: Consulted
Official trial registry consulted: No
Statistical analysis plan consulted: No
Verification boundary: Verification is limited to the specific fields and sources consulted; it is not a full systematic appraisal or GRADE rating.

Source record

Sarcopenia: revised European consensus on definition and diagnosis (2019). Age and ageing.

Source identifiers

Article DOI: 10.1093/ageing/afy169
PubMed record 30312372
PubMed Central: PMC6322506

Controlled study

SURMOUNT-1 DXA: weight, fat and lean soft tissue at 72 weeks

SURMOUNT-1 DXA • NCT04184622

The DXA substudy analyzed 160 participants: 124 receiving pooled tirzepatide doses and 36 receiving placebo. At 72 weeks, changes in weight, fat and lean mass were −21.3%, −33.9% and −10.9% with tirzepatide, versus −5.3%, −8.2% and −2.6% with placebo.

In this analysis, DXA lean mass is fat-free mass minus bone mineral content. It includes tissues other than muscle and, alone, does not describe strength or diagnose sarcopenia.

The article describes roughly three quarters of combined fat and lean mass losses as fat. This sample-level composition does not justify saying that one quarter of lost weight was skeletal muscle.

Evidence design: Randomized trial substudy
Population: Subset of SURMOUNT-1 adults with obesity or overweight and a weight-related complication, without type 2 diabetes; 73.1% female; mean age 46.2 years, weight 102.5 kg and BMI 38.0 kg/m2.
Assessment period: Baseline to week 72
Reported units: percentage points; % change; % of combined fat and lean mass loss; kg

Keep in view

160 of 255 substudy enrollees were analyzed; 5, 10 and 15 mg doses were pooled.
DXA lean mass does not directly measure skeletal muscle or strength.
There was no multiplicity adjustment; missing data from three participants used last observation carried forward.

See study details — SURMOUNT-1 DXA

Study design and methods

Randomized trial substudy

Prespecified DXA body-composition substudy nested within randomized SURMOUNT-1; pooled tirzepatide doses; additional post hoc subgroup analyses.

Population

Subset of SURMOUNT-1 adults with obesity or overweight and a weight-related complication, without type 2 diabetes; 73.1% female; mean age 46.2 years, weight 102.5 kg and BMI 38.0 kg/m2.

Assessment period

Value: 72
Unit: weeks

Parent trial randomized participants

2539

Substudy enrollees

255

Substudy analyzed participants

160

Analyzed participants by arm

Tirzepatide, pooled doses: 124
Placebo: 36

Analysis denominator basis

Participants in the substudy who were randomized, received >=1 dose and had nonmissing baseline and postbaseline DXA measurements. Of 255 enrolled, 160 completed baseline and week-72 or early-discontinuation scans and were included.

Dose pooling

5, 10 and 15 mg tirzepatide pooled; these results cannot be relabeled as a 15-mg-only effect.

Measurement definition

Measurement method: Whole-body dual-energy X-ray absorptiometry (DXA)
Measurement timing: Baseline before first dose and end of treatment at week 72 (within 14 days) or early discontinuation.
DXA lean mass definition: DXA lean mass = fat-free mass minus total bone mineral content. It is lean soft tissue, not a direct skeletal-muscle measurement.
Fat-free mass definition: Includes nonfat tissues such as muscle, bone, organs, ligaments, tendons and water; fat-free mass itself was not the reported endpoint.
Skeletal muscle measured directly: No
Direct strength or physical-performance outcome in this card: No

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extracted outcomes

Reported values, analysis populations and uncertainty, preserved from the curated extraction.
Outcome and group	Reported value	Assessment period	Sample and denominators	Uncertainty
Percent change in body weight Tirzepatide pooled 5/10/15 mg Effect estimate	-21.3 % change least-squares mean Unit: % change	Baseline to week 72 Study weeks 0–72	Reported N: 124 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 124 — substudy analysis arm; scope: Tirzepatide, pooled doses	Arm confidence interval not verified; no reconstruction was performed.
Percent change in body weight Placebo Effect estimate	-5.3 % change least-squares mean Unit: % change	Baseline to week 72 Study weeks 0–72	Reported N: 36 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 36 — substudy analysis arm; scope: Placebo	Arm confidence interval not verified; no reconstruction was performed.
Percent change in body weight Pooled tirzepatide minus placebo Effect estimate	-16 percentage points adjusted mean difference Unit: percentage points	Baseline to week 72 Study weeks 0–72	Reported N: 160 — combined substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	95% confidence interval: -19.4 to -12.6 Reported p-value: <0.001 (between group comparison no multiplicity adjustment)
Percent change in fat mass Tirzepatide pooled 5/10/15 mg Effect estimate	-33.9 % change least-squares mean Unit: % change	Baseline to week 72 Study weeks 0–72	Reported N: 124 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 124 — substudy analysis arm; scope: Tirzepatide, pooled doses	Arm confidence interval not verified; no reconstruction was performed.
Percent change in fat mass Placebo Effect estimate	-8.2 % change least-squares mean Unit: % change	Baseline to week 72 Study weeks 0–72	Reported N: 36 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 36 — substudy analysis arm; scope: Placebo	Arm confidence interval not verified; no reconstruction was performed.
Percent change in fat mass Pooled tirzepatide minus placebo Effect estimate	-25.7 percentage points adjusted mean difference Unit: percentage points	Baseline to week 72 Study weeks 0–72	Reported N: 160 — combined substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	95% confidence interval: -31.4 to -20 Reported p-value: <0.001 (between group comparison no multiplicity adjustment)
Percent change in DXA lean soft tissue mass Tirzepatide pooled 5/10/15 mg Effect estimate	-10.9 % change least-squares mean Unit: % change	Baseline to week 72 Study weeks 0–72	Reported N: 124 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 124 — substudy analysis arm; scope: Tirzepatide, pooled doses	Arm confidence interval not verified; no reconstruction was performed.
Percent change in DXA lean soft tissue mass Placebo Effect estimate	-2.6 % change least-squares mean Unit: % change	Baseline to week 72 Study weeks 0–72	Reported N: 36 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 36 — substudy analysis arm; scope: Placebo	Arm confidence interval not verified; no reconstruction was performed.
Percent change in DXA lean soft tissue mass Pooled tirzepatide minus placebo Effect estimate	-8.3 percentage points adjusted mean difference Unit: percentage points	Baseline to week 72 Study weeks 0–72	Reported N: 160 — combined substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	95% confidence interval: -10.6 to -6.1 Reported p-value: <0.001 (between group comparison no multiplicity adjustment)
Absolute change in fat mass Tirzepatide pooled 5/10/15 mg Effect estimate	-15.9 kg least-squares mean Unit: kg	Baseline to week 72 Study weeks 0–72	Reported N: 124 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 124 — substudy analysis arm; scope: Tirzepatide, pooled doses	Arm confidence interval not verified; no reconstruction was performed.
Absolute change in fat mass Placebo Effect estimate	-3.6 kg least-squares mean Unit: kg	Baseline to week 72 Study weeks 0–72	Reported N: 36 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 36 — substudy analysis arm; scope: Placebo	Arm confidence interval not verified; no reconstruction was performed.
Absolute change in fat mass Pooled tirzepatide minus placebo Effect estimate	-12.3 kg adjusted mean difference Unit: kg	Baseline to week 72 Study weeks 0–72	Reported N: 160 — combined substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	95% confidence interval: -15.1 to -9.6 Reported p-value: <0.001 (between group comparison no multiplicity adjustment)
Absolute change in DXA lean soft tissue mass Tirzepatide pooled 5/10/15 mg Effect estimate	-5.6 kg least-squares mean Unit: kg	Baseline to week 72 Study weeks 0–72	Reported N: 124 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 124 — substudy analysis arm; scope: Tirzepatide, pooled doses	Arm confidence interval not verified; no reconstruction was performed.
Absolute change in DXA lean soft tissue mass Placebo Effect estimate	-1.2 kg least-squares mean Unit: kg	Baseline to week 72 Study weeks 0–72	Reported N: 36 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy 36 — substudy analysis arm; scope: Placebo	Arm confidence interval not verified; no reconstruction was performed.
Absolute change in DXA lean soft tissue mass Pooled tirzepatide minus placebo Effect estimate	-4.4 kg adjusted mean difference Unit: kg	Baseline to week 72 Study weeks 0–72	Reported N: 160 — combined substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	95% confidence interval: -5.6 to -3.2 Reported p-value: <0.001 (between group comparison no multiplicity adjustment)
Fat fraction of combined fat and lean mass losses Pooled tirzepatide Descriptive result; not an effect estimate	74 % of combined fat and lean mass loss reported proportion Unit: % of combined fat and lean mass loss	Baseline to week 72 Study weeks 0–72	Reported N: 124 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	Confidence interval for the fraction not verified.
Lean soft tissue fraction of combined fat and lean mass losses Pooled tirzepatide Descriptive result; not an effect estimate	26 % of combined fat and lean mass loss reported proportion Unit: % of combined fat and lean mass loss	Baseline to week 72 Study weeks 0–72	Reported N: 124 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	Confidence interval for the fraction not verified.
Fat fraction of combined fat and lean mass losses Placebo Descriptive result; not an effect estimate	75 % of combined fat and lean mass loss reported proportion Unit: % of combined fat and lean mass loss	Baseline to week 72 Study weeks 0–72	Reported N: 36 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	Confidence interval for the fraction not verified.
Lean soft tissue fraction of combined fat and lean mass losses Placebo Descriptive result; not an effect estimate	25 % of combined fat and lean mass loss reported proportion Unit: % of combined fat and lean mass loss	Baseline to week 72 Study weeks 0–72	Reported N: 36 — substudy analysis population 2539 — parent trial randomized total; scope: parent trial 255 — substudy enrolled; scope: DXA substudy 160 — substudy analyzed; scope: DXA substudy	Confidence interval for the fraction not verified.

Percent change in body weight — Tirzepatide pooled 5/10/15 mg: extraction context

Outcome role

Exploratory, post hoc

Scale reference

Baseline value of the same tissue or weight

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Percent change in body weight — Placebo: extraction context

Outcome role

Exploratory, post hoc

Scale reference

Baseline value of the same tissue or weight

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Percent change in body weight — Pooled tirzepatide minus placebo: extraction context

Outcome role

Exploratory, post hoc

Scale reference

Difference in percent change

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2

No multiplicity adjustment.

Percent change in fat mass — Tirzepatide pooled 5/10/15 mg: extraction context

Outcome role

primary_substudy_objective

Scale reference

Baseline value of the same tissue or weight

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Percent change in fat mass — Placebo: extraction context

Outcome role

primary_substudy_objective

Scale reference

Baseline value of the same tissue or weight

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Percent change in fat mass — Pooled tirzepatide minus placebo: extraction context

Outcome role

primary_substudy_objective

Scale reference

Difference in percent change

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2

No multiplicity adjustment.

Percent change in DXA lean soft tissue mass — Tirzepatide pooled 5/10/15 mg: extraction context

Outcome role

secondary

Scale reference

Baseline value of the same tissue or weight

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Lean mass means lean soft tissue excluding bone mineral content; it is not skeletal muscle mass.

Percent change in DXA lean soft tissue mass — Placebo: extraction context

Outcome role

secondary

Scale reference

Baseline value of the same tissue or weight

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Lean mass means lean soft tissue excluding bone mineral content; it is not skeletal muscle mass.

Percent change in DXA lean soft tissue mass — Pooled tirzepatide minus placebo: extraction context

Outcome role

secondary

Scale reference

Difference in percent change

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2

No multiplicity adjustment.

Absolute change in fat mass — Tirzepatide pooled 5/10/15 mg: extraction context

Outcome role

secondary

Scale reference

absolute_change

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Absolute change in fat mass — Placebo: extraction context

Outcome role

secondary

Scale reference

absolute_change

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Absolute change in fat mass — Pooled tirzepatide minus placebo: extraction context

Outcome role

secondary

Scale reference

absolute_difference

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2

No multiplicity adjustment.

Absolute change in DXA lean soft tissue mass — Tirzepatide pooled 5/10/15 mg: extraction context

Outcome role

secondary

Scale reference

absolute_change

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Lean mass means lean soft tissue excluding bone mineral content; it is not skeletal muscle mass.

Absolute change in DXA lean soft tissue mass — Placebo: extraction context

Outcome role

secondary

Scale reference

absolute_change

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2; Figure 1 or supplementary Figure S2

Lean mass means lean soft tissue excluding bone mineral content; it is not skeletal muscle mass.

Absolute change in DXA lean soft tissue mass — Pooled tirzepatide minus placebo: extraction context

Outcome role

secondary

Scale reference

absolute_difference

Estimand and analysis rules

Name

Not reported or not verified

Analysis set

Modified intention-to-treat population (efficacy analysis set)

Definition verification status

Full formal estimand not verified; do not inherit the parent-trial treatment-regimen estimand.

Statistical analysis

Analysis population label in the figure: Modified intention-to-treat population (efficacy analysis set)
Statistical model: ANCOVA for body weight, fat and lean measures: baseline response covariate and treatment factor; waist used MMRM.
Missing-data handling: Three missing week-72 observations imputed by last observation carried forward.
Multiplicity adjustment: No
Formal estimand specification: Efficacy analysis set; a separate, fully specified five-attribute estimand was not verified in the substudy full text.
Parent-trial estimand must not be inherited without qualification: Yes

Extraction location

Full text section 3.2

No multiplicity adjustment.

Fat fraction of combined fat and lean mass losses — Pooled tirzepatide: extraction context

Outcome role: Exploratory, post hoc
Scale reference: fat_loss_plus_lean_mass_loss
Extraction location: Full text Table 1 formula and section 3.2

Fraction of combined fat and lean mass losses; not a skeletal-muscle fraction or an individual prediction.

Lean soft tissue fraction of combined fat and lean mass losses — Pooled tirzepatide: extraction context

Outcome role: Exploratory, post hoc
Scale reference: fat_loss_plus_lean_mass_loss
Extraction location: Full text Table 1 formula and section 3.2

Fraction of combined fat and lean mass losses; not a skeletal-muscle fraction or an individual prediction.

Fat fraction of combined fat and lean mass losses — Placebo: extraction context

Outcome role: Exploratory, post hoc
Scale reference: fat_loss_plus_lean_mass_loss
Extraction location: Full text Table 1 formula and section 3.2

Fraction of combined fat and lean mass losses; not a skeletal-muscle fraction or an individual prediction.

Lean soft tissue fraction of combined fat and lean mass losses — Placebo: extraction context

Outcome role: Exploratory, post hoc
Scale reference: fat_loss_plus_lean_mass_loss
Extraction location: Full text Table 1 formula and section 3.2

Fraction of combined fat and lean mass losses; not a skeletal-muscle fraction or an individual prediction.

What the curated evidence supports

The DXA substudy analyzed 160 participants: 124 receiving pooled tirzepatide doses and 36 receiving placebo. At 72 weeks, changes in weight, fat and lean mass were −21.3%, −33.9% and −10.9% with tirzepatide, versus −5.3%, −8.2% and −2.6% with placebo.
In this analysis, DXA lean mass is fat-free mass minus bone mineral content. It includes tissues other than muscle and, alone, does not describe strength or diagnose sarcopenia.
The article describes roughly three quarters of combined fat and lean mass losses as fat. This sample-level composition does not justify saying that one quarter of lost weight was skeletal muscle.

Limitations

160 of 255 substudy enrollees were analyzed; 5, 10 and 15 mg doses were pooled.
DXA lean mass does not directly measure skeletal muscle or strength.
There was no multiplicity adjustment; missing data from three participants used last observation carried forward.

Verification scope

Verified through 2026-11-04 within the consulted scope.

Bibliographic metadata checked: Yes
Original article abstract consulted: Yes
Full-text consultation: Consulted
Official trial registry consulted: Yes
Statistical analysis plan consulted: No
Verification boundary: Verification is limited to the specific fields and sources consulted; it is not a full systematic appraisal or GRADE rating.

Source record

Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study of adults with obesity or overweight (2025). Diabetes, obesity & metabolism.

Source identifiers

Article DOI: 10.1111/dom.16275
PubMed record 39996356
PubMed Central: PMC11965027
Trial registration: NCT04184622
Structured registry: NCT04184622

THE RESEARCH LANDSCAPE

Explore the research landscape

See the scale of the consolidated catalog, the prioritized registry cohort, and the smaller set of evidence cards published in this release.

46,042

Consolidated research records

112,151

Mapped files

Scientific catalog areas

Explore all 16 scientific areas

Clinical obesity and overweight14,981

GLP-1, GIP and incretin medicines2,081

Insulin resistance and glycemic health6,298

Calorie deficit and energy balance580

Thermogenesis and energy expenditure461

Fat oxidation and ketosis74

Intermittent fasting and chrononutrition621

Nutrition, eating and satiety5,932

Muscle preservation and body composition3,735

Gut microbiome and metabolomics607

Physical activity and exercise3,696

Sleep, stress and eating behavior1,358

Weight maintenance and regain164

Bariatric and metabolic surgery2,383

Digital technologies and remote interventions585

Cardiovascular, liver and inflammatory outcomes2,486

Catalog identities consolidate DOI, NCT, PMID, PMCID and normalized titles; the count is not a certified count of independent peer-reviewed publications.

Prioritized clinical registry records

570 records

Weight as a primary outcome: 342
BMI as a primary outcome: 112
Adiposity or waist as a primary outcome: 49
Weight-related outcomes only as secondary outcomes: 29
No direct weight-related outcome identified: 38

Each record has one principal outcome class. This classification does not mean that a trial has only one outcome or that its findings have passed full scientific appraisal.

PUBLISHED CURATED EVIDENCE

13evidence cards

Directed selection of sources and claims verified within the fields and sections actually consulted.

60 result records23 reviewed claims

Search covers these 13 published evidence cards.

Catalog size and metadata completeness do not grade scientific certainty. The 570-record panorama describes a prioritized registry cohort, not 570 publicly reviewed evidence cards.

THE INAUGURAL BRIEFING

Video in preparation

Muscle, Strength & Weight Loss: What Does DXA Measure?

Planned inaugural nuViteo YouTube briefing on DXA lean mass, skeletal muscle, and strength, grounded in the SURMOUNT-1 substudy and EWGSOP2 evidence.

Read the briefing outline

Muscle and strength

Follow the evidence.

EWGSOP2: sarcopenia definition and assessment

Keep in view

Definitions and assessment framework

What the curated evidence supports

Limitations

Verification scope

Source record

Source identifiers

SURMOUNT-1 DXA: weight, fat and lean soft tissue at 72 weeks

Keep in view

Study design and methods

Population

Extracted outcomes

Percent change in body weight — Tirzepatide pooled 5/10/15 mg: extraction context

Percent change in body weight — Placebo: extraction context

Percent change in body weight — Pooled tirzepatide minus placebo: extraction context

Percent change in fat mass — Tirzepatide pooled 5/10/15 mg: extraction context

Percent change in fat mass — Placebo: extraction context

Percent change in fat mass — Pooled tirzepatide minus placebo: extraction context

Percent change in DXA lean soft tissue mass — Tirzepatide pooled 5/10/15 mg: extraction context

Percent change in DXA lean soft tissue mass — Placebo: extraction context

Percent change in DXA lean soft tissue mass — Pooled tirzepatide minus placebo: extraction context

Absolute change in fat mass — Tirzepatide pooled 5/10/15 mg: extraction context

Absolute change in fat mass — Placebo: extraction context

Absolute change in fat mass — Pooled tirzepatide minus placebo: extraction context

Absolute change in DXA lean soft tissue mass — Tirzepatide pooled 5/10/15 mg: extraction context

Absolute change in DXA lean soft tissue mass — Placebo: extraction context

Absolute change in DXA lean soft tissue mass — Pooled tirzepatide minus placebo: extraction context

Fat fraction of combined fat and lean mass losses — Pooled tirzepatide: extraction context

Lean soft tissue fraction of combined fat and lean mass losses — Pooled tirzepatide: extraction context

Fat fraction of combined fat and lean mass losses — Placebo: extraction context

Lean soft tissue fraction of combined fat and lean mass losses — Placebo: extraction context

What the curated evidence supports

Limitations

Verification scope

Source record

Source identifiers

Explore it for yourself.

Body Composition Decoder

Questions for Your Visit

Explore the research landscape

Prioritized clinical registry records

Muscle, Strength & Weight Loss: What Does DXA Measure?