Three weeks of vegan eating left strength and endurance where they were

A common worry about switching to plant-only eating is that training will suffer. A small trial published on October 22 in Translational Exercise Biomedicine tested that over three weeks, in people who were already training regularly.

How the trial worked

The authors, Pohl, Schünemann, Böker, Reeb and Gehlert, recruited 24 healthy, physically active adults who normally ate an omnivorous diet. Everyone first went through a baseline phase with standardized training and a record of what they ate.

They were then randomized to one of two vegan versions for three weeks. One group ate as much as they wanted. The other ate a vegan diet matched to the calories they had been eating before. Throughout, everyone did two strength sessions and two endurance sessions a week.

The main outcomes were maximal isometric strength and peak oxygen uptake, a standard measure of aerobic fitness. The team also tracked body composition, food intake, resting energy use, daily activity and how people said they felt. Measurements were taken at baseline, after the three weeks, and again after people went back to their usual diet.

What held, and what changed

All 24 people finished. Strength and peak oxygen uptake were maintained in both groups. Muscle mass didn't change.

Body mass and body fat went down in both groups. In the group that ate freely, energy and protein intake fell. In the calorie-matched group, intake stayed stable. Fiber intake rose in both.

People in both groups reported better sleep quality, and the calorie-matched group also reported better general physical well-being.

How far this goes

This is a short trial with 24 people, so it says little about months or years. Three weeks is enough to see whether performance drops quickly, not what happens over a full training cycle.

The well-being results are self-reported, and participants knew what they were eating, which can shape how people rate their sleep or mood. The drop in body mass in the free-eating group also came with eating less, so not every change can be put down to the type of food alone.

The trial also doesn't say anyone should change how they eat. It describes what happened to a group of active adults under a set routine.

Where Soma fits

What interests us is the gap between what changed and what didn't. Body composition moved within weeks while performance held steady, and you only see that split if you measure several things, the same way, before and after.

Soma is a general wellness product, not a medical device. It doesn't diagnose anything, and it doesn't measure strength or aerobic fitness. Soma Axon, the pod we are still building, uses the same light, cameras and stance every week, and shows each value with its margin of error, so a change over time is easier to trust. We wrote more about that in The same instrument, every week.

Sources, as of October 25, 2026: Pohl, Schünemann, Böker, Reeb and Gehlert, Translational Exercise Biomedicine, published under CC BY 4.0. This post describes research and isn't medical advice.