How do you tell if your thighs are made of fat or muscle

If you piece all the above answers together, you get some inkling of reality.

Thighs are made up of a bone (femur), and the muscles attached to them (quadriceps & ‘hamstrings’), and overlying tissues (fat, or adipose tissue, and skin [the ‘cutaneous’ layer]). Someone with “fat things” probably has quite a bit of muscle, but a very thick layer of fat under the skin (subcutaneous adipose tissue). A thigh with a thin layer of subcutaneous adipose tissue would be considered ‘thin’ by most people. It could, however, be rather large; for example, if the owner of the thigh was a competition cyclist like Lance Armstrong, a speed skater, a weight-lifter, etc.

There are at least two “easy” tests to help you decide about your own thighs. The “jiggle” test, alluded to above: firmly flex and hold your thigh muscles tight, then dance (perhaps like the “Twist”) a moment. Stop suddenly … if your thighs stop when you do, it’s probably mostly muscle down there. If they continue a second … “they would be jiggly”, ishaybabe said. She’s right.

You can also pinch your thighs while they are flexed, much like your stomach or abdomen. If you flex your thighs and can pinch very little tissue above the muscles, you have thin(ner) thighs. If you can pinch a lot when your thighs are flexed, you have a deeper layer of fatty tissue on them.