Is plant-based protein supplementation as effective as whey protein? A systematic review and meta-analysis in untrained adults undergoing resistance training.

In 30 seconds

This systematic review and meta-analysis compared plant-based with whey protein supplementation for body composition in untrained adults aged 18–59 years undertaking resistance training. Five studies met the criteria for qualitative synthesis and meta-analysis, with outcomes assessed using dual-energy X-ray absorptiometry. Both supplement types, when combined with training, were associated with improvements in lean body mass and body fat mass. The analysis found no statistically significant between-group differences, but the limited evidence does not establish that the protein sources are physiologically equivalent.

Key findings

• Five studies were included in the qualitative synthesis and meta-analysis.
• Plant-based and whey protein supplementation alongside resistance training were both associated with improvements in lean body mass and body fat mass.
• No statistically significant between-group differences in body composition outcomes were observed.
• Evidence for chia-based protein was limited to one study, which did not demonstrate significant lean body mass changes.

Why it matters

The findings suggest that soy- or pea-based supplements may be options for adults beginning resistance training who prefer alternatives to whey. However, absence of a statistically significant difference is not proof of equivalence. The small evidence base and wide confidence intervals mean that comparative effects remain uncertain, so conclusions about protein-source superiority should be cautious.

What to keep in mind

Only five studies were included, and the source notes wide confidence intervals and limited evidence, particularly for chia-based protein. The analysis therefore cannot establish physiological equivalence between plant-based and whey protein.