I believe that's an interview, so we have to forgive him for the lack of clarity. He means that if you look at the studies, you will not see a figure for the amount of animal protein in a diet, but you will see a figure for total fat consumption. Animal products typically contain a lot more fat than plant products, so we can use the fat figure as an indicator of the protein intake.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
enoonI believe that's an interviewYes, you're right. Thank you for your clarifications.