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New Trial Compared Muscle Gains in Vegetarians And Meat Eaters. One Difference Stood Out. : ScienceAlert (opens in a new tab)

New Trial Compared Muscle Gains in Vegetarians And Meat Eaters. One Difference Stood Out. · 2026-10-10

Short answerEvidenceSource

Short answer

Mixed

Mixed.

One claim goes further than the study. 2 other points were not covered by the paper.

  • 3 supported
  • 1 overstated
  • 2 not covered

Checked against the study summary. The full text wasn't available, so some details couldn't be settled either way.

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Follow the evidence trail
1

The story

New Trial Compared Muscle Gains in Vegetarians And Meat Eaters. One Difference Stood Out. : ScienceAlert

New Trial Compared Muscle Gains in Vegetarians And Meat Eaters. One Difference Stood Out. · 2026-10-10

The story’s checkable claims.

Read the original story (opens in a new tab)
2

NewsLink checks it

Mixed

One claim overstates the study. Three of six check out. Two claims the study doesn't address.

  • 3 supported
  • 1 overstated
  • 2 not covered
Open claim evidence
3
Then inspect each claim

Evidence layer

Claim by claim

Each claim gets a verdict. Expand it to see the evidence directly below.

6 claims in this story

Showing all 6 claimsChoose a verdict to focus the list.

Claim 1 of 6OverstatedMuscle mass in the legs and arms increased in both groups, but omnivores showed about 70 percent more gains, described as +0.66 kilograms compared with +0.38 kilograms for vegetarians.View evidenceHide evidence

As statedabout 70 percent more gains; +0.66 kilograms vs +0.38 kg

Why this verdict

The stated within-group appendicular muscle mass changes match the profile: vegetarian +0.38 kg and omnivorous +0.66 kg. However, the story's unhedged framing that omnivores showed about 70% more gains can imply a clear between-group advantage, while the abstract-level profile says noninferiority for appendicular muscle mass was not established and the between-group confidence interval crossed zero (-0.33 kg; 95% CI -0.69 to 0.03).

1

Study evidence

Noninferiority of the vegetarian diet for change in appendicular muscle mass was not established: between-group difference -0.33 kg (95% CI: -0.69, 0.03 kg).-0.33 kg (95% CI -0.69 to 0.03)

“Primary outcomes were protein intake… and appendicular muscle mass (dual-energy x-ray absorptiometry), with noninferiority margins… 0.25 kg, respectively.”
Claim 2 of 6Not coveredThe article says it is not clear whether the muscle-mass difference was due to lower protein intake among vegetarians or to protein quality from animal-based foods.View evidenceHide evidence

Why this verdict

The abstract-level profile confirms lower protein intake in the vegetarian arm and different plant/animal protein targets, but it does not provide a mechanism or mediation analysis showing whether the muscle-mass pattern was due to total protein intake, protein quality, or another factor. The speculative caveat is plausible, but not directly verifiable from the supplied abstract-depth profile.

1

Study evidence

Vegetarian diet produced lower protein intake than omnivorous diet; noninferiority for protein intake (margin 0.12 g/kg/d) was not established.−0.33 g/kg/d (95% CI: −0.49, −0.17 g/kg/d)

“In this randomized noninferiority trial, 108 adults… received dietary counseling for either a lacto-ovo vegetarian or an omnivorous diet.”
2

Study evidence

Noninferiority of the vegetarian diet for change in appendicular muscle mass was not established: between-group difference -0.33 kg (95% CI: -0.69, 0.03 kg).-0.33 kg (95% CI -0.69 to 0.03)

“Primary outcomes were protein intake… and appendicular muscle mass (dual-energy x-ray absorptiometry), with noninferiority margins… 0.25 kg, respectively.”
Claim 3 of 6Not coveredThe story says vegetarians who ate more protein tended to gain more muscle, whereas meat eaters who ate more protein did not.View evidenceHide evidence

Why this verdict

The supplied abstract-depth profile reports group-level protein intake and appendicular muscle mass changes, but it does not report within-group associations between higher protein intake and muscle gain separately for vegetarians and omnivores. This claim may require full-paper subgroup or correlation analyses not present in the profile.

1

Study evidence

Vegetarian diet produced lower protein intake than omnivorous diet; noninferiority for protein intake (margin 0.12 g/kg/d) was not established.−0.33 g/kg/d (95% CI: −0.49, −0.17 g/kg/d)

“In this randomized noninferiority trial, 108 adults… received dietary counseling for either a lacto-ovo vegetarian or an omnivorous diet.”
2

Study evidence

Noninferiority of the vegetarian diet for change in appendicular muscle mass was not established: between-group difference -0.33 kg (95% CI: -0.69, 0.03 kg).-0.33 kg (95% CI -0.69 to 0.03)

“Primary outcomes were protein intake… and appendicular muscle mass (dual-energy x-ray absorptiometry), with noninferiority margins… 0.25 kg, respectively.”
Claim 4 of 6SupportedA new clinical trial found that among adults aged 55 and over, both vegetarians and meat eaters gained muscle and showed similar improvements in strength and physical performance after 12 weeks of resistance training.View evidenceHide evidence

As stated12 weeks

Why this verdict

The abstract-level profile reports significant within-group increases in appendicular muscle mass in both diet arms over 12 weeks, and reports that leg press strength and chair stand performance improved in both groups with no between-group differences. The evidence is strongest for appendicular muscle mass, leg press, and chair stand; handgrip was listed but not reported in the abstract.

1

Study evidence

Noninferiority of the vegetarian diet for change in appendicular muscle mass was not established: between-group difference -0.33 kg (95% CI: -0.69, 0.03 kg).-0.33 kg (95% CI -0.69 to 0.03)

“Primary outcomes were protein intake… and appendicular muscle mass (dual-energy x-ray absorptiometry), with noninferiority margins… 0.25 kg, respectively.”
2

Study evidence

Leg press strength increased significantly in both the vegetarian and omnivorous diet groups during the 12-week resistance training program, with no between-group differences reported in the abstract.

“Secondary outcomes included leg press strength, chair stand test, and handgrip strength.”
Claim 5 of 6SupportedThe trial was randomized and enrolled 108 adults who followed either a vegetarian diet or an omnivorous diet for three months while doing resistance training three times a week.View evidenceHide evidence

As stated108 adults; 3 months; 3 sessions per week

Why this verdict

The profile describes a randomized noninferiority trial with 108 adults aged at least 55 years, assigned to dietary counseling for either lacto-ovo vegetarian or omnivorous diets, with both groups completing a 12-week resistance training program of 3 sessions per week. The story's 'followed either diet' wording is broadly consistent, though the paper profile specifies self-selected diets after counseling.

1

Study evidence

Vegetarian diet produced lower protein intake than omnivorous diet; noninferiority for protein intake (margin 0.12 g/kg/d) was not established.−0.33 g/kg/d (95% CI: −0.49, −0.17 g/kg/d)

“In this randomized noninferiority trial, 108 adults… received dietary counseling for either a lacto-ovo vegetarian or an omnivorous diet.”
2

Study evidence

Noninferiority of the vegetarian diet for change in appendicular muscle mass was not established: between-group difference -0.33 kg (95% CI: -0.69, 0.03 kg).-0.33 kg (95% CI -0.69 to 0.03)

“Primary outcomes were protein intake… and appendicular muscle mass (dual-energy x-ray absorptiometry), with noninferiority margins… 0.25 kg, respectively.”
Claim 6 of 6SupportedThe article concludes that a predominantly plant-based diet can still support meaningful improvements in muscle mass, strength, and physical function when protein intake is sufficiently high and combined with resistance training.View evidenceHide evidence

Why this verdict

The profile reports that the vegetarian arm achieved mean protein intake above the target of ≥1.2 g/kg/day, gained appendicular muscle mass, and improved selected strength/function outcomes during the 12-week resistance training program. This supports the qualified conclusion that a predominantly plant-based/lacto-ovo vegetarian diet can accompany improvements when protein intake is adequate and resistance training is performed, though the profile also shows vegetarian noninferiority versus omnivorous diet was not established.

1

Study evidence

Vegetarian diet produced lower protein intake than omnivorous diet; noninferiority for protein intake (margin 0.12 g/kg/d) was not established.−0.33 g/kg/d (95% CI: −0.49, −0.17 g/kg/d)

“In this randomized noninferiority trial, 108 adults… received dietary counseling for either a lacto-ovo vegetarian or an omnivorous diet.”
2

Study evidence

Noninferiority of the vegetarian diet for change in appendicular muscle mass was not established: between-group difference -0.33 kg (95% CI: -0.69, 0.03 kg).-0.33 kg (95% CI -0.69 to 0.03)

“Primary outcomes were protein intake… and appendicular muscle mass (dual-energy x-ray absorptiometry), with noninferiority margins… 0.25 kg, respectively.”
Then look for missing context

Context layer

What the story left out

Important study details the story did not include.

  • Primary protein-intake finding: noninferiority for protein intake was not demonstrated; the vegetarian group had lower mean protein intake than the omnivorous group, although both groups met the ≥1.2 g/kg/day target.

    The story mentions that lower protein intake might explain the muscle-mass difference and emphasizes sufficient protein, but it does not clearly report the paper's primary noninferiority result for protein intake or the magnitude of the group difference.

    From randomized noninferiority trial

  • Primary appendicular muscle mass finding: both groups gained appendicular muscle mass, but noninferiority of the vegetarian diet versus the omnivorous diet was not established, and the between-group confidence interval crossed zero.

    The story reports the within-group gains and presents the omnivore gain as about 70% larger, but it does not convey the noninferiority framing or the uncertainty in the between-group estimate, which is important for interpreting whether one diet clearly outperformed the other.

    From randomized noninferiority trial

  • Abstract-depth limitations for functional outcomes: numeric effect sizes, confidence intervals, p-values, detailed testing protocols, and assessor-blinding information are not provided for the secondary strength/function outcomes.

    The story's caveats mention demographic generalizability and uncertainty about the reason for muscle-gain differences, but it does not mention the abstract-level reporting limitations for the secondary functional outcomes.

    From Randomized trial (secondary outcomes within a 12-week resistance training intervention)

3 things the story did carry across
  • Trial design: randomized noninferiority trial in 108 adults aged ≥55 years comparing lacto-ovo vegetarian versus omnivorous diet counseling during a shared 12-week resistance training program.
  • Diet implementation: diets were self-selected after counseling, with targets of ≥1.2 g/kg/day protein and ≥60% plant-based protein in the vegetarian arm or ≥60% animal-based protein in the omnivorous arm.
  • Secondary functional outcomes: leg press strength and chair stand performance improved in both groups with no between-group differences; handgrip strength was listed but not reported in the abstract.
Then read the study layer

Study layer

Study at a glance

Scan the study first. Expand only the parts you want to inspect.

Pieces of work

3

Evidence read

study summary

Lead result

human in vivo

1Lead resulthuman in vivoTest whether a self-selected lacto-ovo vegetarian diet (≥60% plant protein) is noninferior to an omnivorous diet (≥60% animal protein) for achieving adequate protein intake during a standardized 12-week resistance training program in adults aged ≥55 years.randomized noninferiority trialExpand

In plain English

Randomized noninferiority trial in adults ≥55 y comparing self-selected lacto-ovo vegetarian (target ≥60% plant protein) versus omnivorous (target ≥60% animal protein) diets combined with a 12-week, thrice-weekly resistance training program. Primary outcome was protein intake (3-d food record) with a noninferiority margin of 0.12 g/kg/d. The vegetarian arm had lower protein intake than the omnivorous arm and noninferiority was not demonstrated; both groups nonetheless met the targeted ≥1.2 g/kg/d and both groups showed gains in appendicular muscle mass and strength.

Key findings

  • Vegetarian diet produced lower protein intake than omnivorous diet; noninferiority for protein intake (margin 0.12 g/kg/d) was not established.−0.33 g/kg/d (95% CI: −0.49, −0.17 g/kg/d)
  • Noninferiority for appendicular muscle mass was not demonstrated between vegetarian and omnivorous arms.−0.33 kg (95% CI: −0.69, 0.03 kg)
“In this randomized noninferiority trial, 108 adults… received dietary counseling for either a lacto-ovo vegetarian or an omnivorous diet.”
2human in vivoTest whether the vegetarian diet is noninferior to the omnivorous diet for changes in appendicular muscle mass during the same 12-week resistance training program.randomized noninferiority trialExpand

In plain English

Randomized noninferiority trial (IMPACT) in 108 adults ≥55 y comparing a self-selected lacto-ovo vegetarian versus omnivorous diet, each combined with a 12-week resistance training program, assessing appendicular muscle mass by DXA as a prespecified primary outcome with a noninferiority margin of 0.25 kg. Noninferiority of the vegetarian diet for change in appendicular muscle mass was not demonstrated (between-group difference -0.33 kg; 95% CI: -0.69, 0.03 kg). Both groups achieved the prespecified protein intake targets (≥1.2 g/kg/d) and showed within-group increases in appendicular muscle mass.

Key findings

  • Noninferiority of the vegetarian diet for change in appendicular muscle mass was not established: between-group difference -0.33 kg (95% CI: -0.69, 0.03 kg).-0.33 kg (95% CI -0.69 to 0.03)
  • Both groups showed significant within-group increases in appendicular muscle mass over 12 weeks: vegetarian +0.38 kg (95% CI: 0.12, 0.64 kg); omnivorous +0.66 kg (95% CI: 0.40, 0.93 kg).
“Primary outcomes were protein intake… and appendicular muscle mass (dual-energy x-ray absorptiometry), with noninferiority margins… 0.25 kg, respectively.”
3human in vivoCompare the effects of the two diet arms (with the same resistance training) on secondary functional outcomes (leg press strength, chair stand performance, handgrip strength).Randomized trial (secondary outcomes within a 12-week resistance training intervention)Expand

In plain English

Within this 12-week randomized trial of lacto-ovo vegetarian versus omnivorous diets combined with standardized resistance training, secondary functional outcomes (leg press strength, chair stand test, handgrip strength) were assessed. The abstract reports that leg press strength and chair stand performance significantly improved in both diet groups with no between-group differences; the abstract does not report results for handgrip strength. Detailed testing protocols and numeric effect sizes for these secondary outcomes are not provided in the abstract.

Key findings

  • Leg press strength increased significantly in both the vegetarian and omnivorous diet groups during the 12-week resistance training program, with no between-group differences reported in the abstract.
  • Chair stand test performance improved significantly in both diet groups during the intervention, with no between-group differences reported in the abstract.
“Secondary outcomes included leg press strength, chair stand test, and handgrip strength.”
What this piece can’t prove
  • Abstract provides only summary statements for secondary functional outcomes without numeric effect sizes, confidence intervals, or detailed p-values.
  • As secondary endpoints, these outcomes may have been analyzed with less prespecification or statistical power than primary endpoints; abstract does not provide information on multiplicity or adjustment.

2 further details could not be confirmed from the summary.

Finally, the search trail

Method layer

NewsLink found the paper. Tessa takes you deeper.

NewsLink checks the story. Tessa is where you inspect the paper, authors, evidence, and research context.

Open the paper in Tessa

Effects of a self-selected vegetarian compared with omnivorous diet on protein intake and muscle mass in older adults during resistance exercise: the IMPACT randomized controlled trial

The American journal of clinical nutrition · 2026

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Why this one

Near certain

NewsLink found the paper. Tessa is where you inspect it deeply.

Papers considered

The selected paper, plus nearby candidates.

PubMed, Europe PMC, Crossref · 15 candidate papers

Selected

Effects of a self-selected vegetarian compared with omnivorous diet on protein intake and muscle mass in older adults during resistance exercise: the IMPACT randomized controlled trial

The American Journal of Clinical Nutrition · 2026 · PubMed, Europe PMC, Crossref

Tessa (opens in a new tab)Source (opens in a new tab)
Candidate

Are plant-based and omnivorous diets the same for muscle hypertrophy? A narrative review of possible challenges of plant-based diets in resistance-trained athletes.

Nutrition (Burbank, Los Angeles County, Calif.) · 2025 · PubMed, Europe PMC

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Candidate

P3-12-03 - Sex differences in association of protein intake with loss of appendicular lean mass in older adults

2019 · Crossref

Source (opens in a new tab)

And 9 more candidates considered.