This post will cover the proposed mechanism as to why potassium "debloats", provides the counter-argument against why that mechanism is false. Lastly, it will essentially contradict the previous sections because none of these mechanisms are actually real or observed within the body, it's just a poor understanding of basic biology and homeostasis.
mandibularp
what is potassium and how is it dissolved
Potassium is an atom and is present within our body and is present in an ionic form, K+. Because it is a cation (a positive ion) it is soluble in water. The reason for why K+ is soluble in water is because water, H2O, is itself a polar molecule. The oxygen atom has a greater electronegativity (The uneven distribution of electrons in a covalent bond) than hydrogen. So in the H-O-H instead of the electron sitting in a probability cloud that is most dense at the center of the H--'--O bond, it is instead more like this H---'-O. Here, for the example the apostrophe represents where the electron density is greatest. In a covalent bond with no electronegativity the electron density is greatest in the middle of the two atoms. Because oxygen has a greater electronegativity than hydrogen it effectively has a greater pull on the electron which shifts the density probability more towards the oxygen. Because of this shift a dipole is created, the oxygen is partially negative and the hydrogen is partially positive. Because the partially negative oxygen wants to be neutral it is now willing to transiently interact and able to form weak transient non-covalent interactions with positively charged molecules (see image 1). This increases the entropy of the arrangement (entropy is essentially a measure of disorder and the universe wants to be more disordered) because it lowers the chemical potential of the water. The lowering of chemical potential of water causes the water potential to be lower. Pure water has a water potential of 0 and adding solutes makes the water potential more negative. Water will move from an area of high water potential to an area of low water potential. This is because when water randomly moves, and during osmosis crosses a semi-permeable membrane, there is a greater NET movement in a given direction. Looking at image 2, the left hand side has a water potential of 0, pure water, and the right hand side a water potential of -20. Due to this water will passively move from left -> right until equilibrium is reached (the movement of water left and right is at an equal rate that there is no change in concentration on either side).The proposed mechanism
Given what I have stated above, in an isolated environment if pure water if an empty cell with only potassium in it is placed into the environment; water will move into the cell. However, in our bodies the cell is not empty and the environment is not pure water. The inside of the cell has multiple solutes, the outside of the cell has it's own solutes - each of which produce a water potential with the movement of the direction of water being towards the lower side. Because the interstitial environment consists largely of water if the extracellular environment has a lower water potential water will sit here more and increase the volume of the extracellular environment making you look bloated. Increasing potassium intake will increase the concentration of potassium within a cell, lowering the intercellular environments water potential and causes water to leave the extracellular environment, thus shrinking it and reducing bloat.why this proposed mechanism falls short
The water molecules shift only a small distance, a couple to a couple hundred nanometers at best. When we look at our face we expect to see a difference on the scale of millimeters to possibly even centimeters. This is a scale factor difference of 1,000,000X. The slight shift in were water is located will not cause any appreciable change in your cheeks puffiness.
mandibularp
