Last year the number of American organ donors hit a milestone when the 100 millionth person added their name to the list. But before you boast about signing up, you might want to step onto a scale.

While only a portion of Americans say they’ll will their remains to needy would-be recipients, organ donors in the US aren’t excluded from a statistic that is impacting the US as a whole. America’s obesity epidemic is now taking a toll on organ donations, with around one quarter of those willing to help tipping the scales at a weight that makes their vital organs unwanted and unusable.