The Claim
Long-term supplementation with plant-based protein (primarily soy) results in no statistically significant differences in lean body mass, fat mass, or total body mass compared to animal-based protein (primarily dairy) in adults aged 18 and older when daily protein intake is adequate and supplementation lasts 6 to 31 months.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
When adults consume adequate amounts of protein, replacing animal protein with plant protein from soy does not change lean body mass, fat mass, or total body weight over 6 to 31 months.
See the scientific wording
Long-term supplementation with plant-based protein (primarily soy) does not result in statistically significant differences in lean body mass, fat mass, or total body mass compared to animal-based protein (primarily dairy) in adults aged 18 and older, when daily protein intake is adequate and supplementation lasts 6 to 31 months, suggesting protein source may be less critical than total intake for body composition outcomes.
When enough protein is eaten every day, the body breaks down all proteins into amino acids and uses them to build and repair muscle tissue. Whether the amino acids come from soy or dairy, the same building blocks are available, so muscle mass stays the same. Fat and total body mass also stay unchanged because the total energy and protein supply determines how the body stores or uses fat, not where the protein came from.
What the research says
1 studyWhen adults took soy protein or dairy protein supplements for six months to over two years, and ate enough protein overall, their muscle and fat levels changed in almost exactly the same way — so the source of the protein didn’t matter much.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.