Research

Macro partitioning

Amateur male bodybuilders consuming high-protein diets (average 1.8 g/kg, up to 3.7 g/kg) combined with protein supplements exhibit significantly higher body fat percentages and thigh skinfold thickness compared to those with lower protein intake.

If you are an amateur bodybuilder, be careful with protein supplements. This study found that higher protein intake, especially from supplements, was linked to higher body fat. You likely don't need more than 1.6-1.8 g/kg of protein from food alone. Focus on whole food sources and avoid stacking multiple protein supplements, as this may lead to excess calories and fat gain rather than muscle.

ModerateSupportsMEDIUM confidence
There is a statistically significant positive correlation between the measures of skin-fat folds on the thigh and the amount of protein consumed by amateur bodybuilders, which means that a higher skinfold measure was associated with higher protein intake. The fat mass is influenced by the consumption of protein from supplements, and if the respondents consumed more protein from nutrients, their fat mass increased (Table 5).
A Karpik et al. · American Journal of Men s Health · 2020

Why this rating

Observational cross-sectional study with self-reported dietary data; correlation does not prove causation, but the trend is statistically significant.

Source

Evaluation of Protein Content in the Diet of Amateur Male Bodybuilder

A Karpik et al. · American Journal of Men s Health · 2020

DOI 10.1177/1557988320970267

cross_sectional · n=35Cited 11×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →