A 12-week trial found muscle and strength gains in both diet groups after 55, with more muscle gained by omnivores. Here is the practical context.
On October 10, 2026, ScienceAlert reported on the IMPACT randomized trial from researchers at Amsterdam University of Applied Sciences, with results published in the American Journal of Clinical Nutrition. The trial compared vegetarian and omnivorous eating during resistance training in adults aged 55 and over.
ScienceAlert’s account describes a study in which both groups made progress, but not identical progress:
The Men’s Journal coverage also centered its headline on adults over 55 building muscle without meat. That is a useful starting point, but the complete finding includes the larger average muscle gain among omnivores.
For someone whose main goal is adding muscle, the difference deserves attention. Reporting only that both groups improved would leave out a result directly relevant to that goal. Reporting only that omnivores gained more would erase the vegetarian group’s progress.
The useful reading holds both findings together. Vegetarian participants added muscle during the program. Omnivorous participants added more on average, while the reported strength and performance results did not show a statistically significant separation.
These outcomes answer different questions. Arm-and-leg muscle mass addresses a body-composition goal. Leg-press performance and chair stands address aspects of strength and physical function. For a man thinking about healthy aging, none needs to cancel out the others.
The diet distinction matters: this was not a vegan-diet test. ScienceAlert also describes participants as predominantly White, healthy and highly educated. The sample and the 12-week duration limit how confidently the findings can be applied elsewhere. Men aged 35 to 54 and gay men as a distinct population were not directly addressed by this trial.
There is also a statistical boundary. No statistically significant difference in strength or performance does not prove that the diets are equivalent. The reported muscle-mass figures are group averages rather than forecasts for an individual. ScienceAlert’s account does not provide the detailed statistical information needed for stronger claims about those differences.
The explanation for the muscle-mass gap remains unresolved. ScienceAlert says it is unclear whether protein quantity or protein quality accounts for it, and it does not give each group’s exact average intake. Within the vegetarian group, higher protein intake tended to accompany greater muscle gains; that association does not establish causation. Researchers proposed that omnivores may have reached a threshold beyond which extra protein offered no further benefit, but that remains a hypothesis.
The practical value is not a verdict on which diet makes someone a more serious lifter. It is a clearer way to separate a food preference from a training plan and from the outcomes that matter personally. For gay men interested in strength and body composition, that is more useful than turning food choices into competing identities.
The study was not simply a comparison of what people ate. Participants trained regularly and received nutrition support. Any practical reading needs to keep that full setting in view rather than crediting a diet label alone.
ScienceAlert reports three resistance sessions weekly, using exercises for several parts of the body. That describes the program tested. It is not evidence that changing food choices while leaving training out would reproduce the gains.
For daily planning, the useful question is whether resistance training has a reliable place in the week. That question comes before treating a switch between vegetarian and omnivorous eating as the central decision. GayFitLab’s guide to thinking through a manageable training week offers a related place to continue that discussion.
For someone who prefers vegetarian meals, the gains reported here are a reason to take that preference seriously within a muscle-building plan. The vegetarian participants made progress while excluding meat and fish. Eggs and dairy remained available within their eating pattern.
The researchers’ interpretation, reported by ScienceAlert, was that predominantly plant-based eating can support meaningful improvements when sufficiently high protein intake accompanies resistance training. The practical emphasis belongs on the combination. A dietary identity tells only part of the story.
A useful next conversation with a qualified dietitian would address the actual foods in a person’s routine and how protein fits into them. That is a more specific question than asking whether all vegetarian diets are suitable for muscle gain. GayFitLab also has a broader discussion of everyday protein planning for readers weighing that part of their routine.
The researchers specifically highlighted protein targets and protein quality for people with low appetite or low overall energy intake. That is a practical detail worth retaining. It shifts attention from the name of the diet to whether the eating pattern is meeting the person’s needs.
For a reader who struggles to eat enough, those circumstances belong in a discussion with a qualified clinician or dietitian. The study’s protein target describes a research condition rather than a personal prescription. Individual nutrition decisions need to account for the person, not just the headline.
The outcome of that conversation need not be an automatic move toward meat. The question is how a preferred eating pattern fits the person’s goals and circumstances. The researchers themselves pointed to individual context when discussing the suitability of a more plant-based diet.
If the main objective is muscle growth, the larger average gain among omnivores is relevant. There is no need to soften that result to make vegetarian eating sound viable. Its viability in this trial is supported by the gains the vegetarian group actually recorded.
If the objective includes physical capability, the strength and performance findings also deserve space. Both groups improved on those outcomes. A body-composition discussion that stops at muscle mass would leave those results out.
For a man thinking about health span, the editorial takeaway is to keep both categories in view. Looking more muscular and feeling physically capable can be compatible priorities without being interchangeable. GayFitLab’s discussion of thinking about muscle beyond its size provides related context for that distinction.
An omnivorous reader can reasonably note the larger average muscle gain without treating it as a universal rule. A vegetarian reader can reasonably note the progress without describing the diets as identical. Neither position requires ignoring an inconvenient part of the result.
For someone deciding whether to change an established eating pattern, this study is useful material for a conversation rather than a command to switch. Personal priorities may include muscle growth and physical capability alongside food preferences. Those priorities deserve to be stated clearly before choosing what to change.
The most productive question is not which group “won.” It is which finding matters to the decision at hand. For this trial, that means recognizing a muscle-growth advantage for omnivores alongside meaningful progress in both groups.
Keep resistance training central, plan protein within the eating pattern you prefer and judge progress through both muscle and physical function rather than treating this trial as a reason for an automatic diet switch.
Keeping vegetarian meals compatible with strength goals puts diet planning at the center of this story, where GayFitLab supplies evidence-led editorial context. For gay men 35+ concerned about changing energy or physical capability, its coverage connects fitness and nutrition with healthy aging while separating credible findings from exaggerated promises.
Stay connected for research-led guidance on fitness, body composition, skin, grooming, vitality, sexual wellbeing, relationships and healthy aging. Clear ideas for gay men 35+ who want to look good, feel strong and age with confidence.
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