10/06/2026
I was talking about protein last March when I drew a barrel on the whiteboard.
(Not my best artwork! One of my students told me it looked like a badly squished coffee cup.)
But the barrel metaphor is one I come back to because it explains something most women have never been told about how protein actually works in the body.
Think of an oak barrel built from 9 individual wooden staves (planks) - each one representing one of the nine essential amino acids. When all the staves are the same height, the barrel holds water to the top. Every amino acid is available and used. Nothing is wasted.
But if one stave is shorter than the rest - even by a small amount - the barrel can only fill to the height of that shorter stave. The amino acids above the waterline? Your body can't use them.
They're simply excreted.
This is why variety matters more than volume.
You can eat a lot of protein and still be short on the specific amino acids your body needs - if you're eating from too narrow a range. A diet built almost entirely on one source, however good that source is, will always have a short stave somewhere.
Animal proteins - eggs, meat, fish, dairy - tend to contain all nine essential amino acids in good proportions. That's why they score so highly on protein quality measures. Plant proteins can be lower in one or more, which is why variety and combination matter more if you rely more on them.
The goal isn't just more protein. It's the right protein, from a wide enough range of sources, consistently throughout the day.
Fill the barrel.