Ghee lubricates your joints.
What is a lubricated joint?
A rather commonly cited advantage of consuming ghee is that your joints can move more freely. Much like spraying WD40 on a squeaky hinge will get a door or metal joint moving freely. WD40 does this by loosening up rust, and reducing the friction and allowing two surfaces to move more smoothly along each other.
Does ghee or any other food directly do this for the human body?
Nope.
No food is directly transported in the blood stream to the knee to be used as a lubricant. And even if you found a way to directly apply ghee on the joint, the body will be throughly confused and ask the immune system to viciously attack the stuff.
Human joints are far more complicated than a door hinge. Not just in terms of the movement they produce. And the ability to produce force quite gradually. But also in how they are constructed to get the job done. And how they rebuild cells. How they receive nutrients. Etc etc.
There are parts of the joint that actually produce the movement aka joints. These are bones.
There are parts of the joint that control the way the joints interact to produce movement in a fixed arc or range. These are ligaments that connect the bones. And tendons that connect muscles to bones.
Then there are parts of the joint that reduce the friction between two bones as they move along reach other. These are the cartilage, meniscus (a type of cartilage) and the fat pad (adipose tissue that absorbs shock).
Vivid visuals don’t translate to reality
Among the many many different molecules that make up your cartilage, meniscus and fat pad are aggrecans, elastin, adipose cells etc. All those molecules are synthesised by your body using the nutrients found in any healthy diet. Nothing found in ghee lends itself as a special ingredient for making the adipose tissue or protein found in the connective tissue in joints that helps the joint articulate more smoothly.
Long story short: There’s one good reason to eat ghee. It tastes good. And eat it sparingly and in a very measured way.
PS: The positively disgusting and disturbing image below is what happens when you ask AI to generate an image of a man eating ghee and apply it on the knee too. Good times.