@VinnyJames
Hi,
The personal fat threshold is the amount of fat a person can carry before they trigger glucose intolerance.
For example, a person might have an apparently normally functioning metabolism at 9, 10 or even 14 stone. But when the scales hit 15 stone, they start to experience glucose intolerance, which makes weight gain easier, and as the pounds pile on, type 2 diabetes appears. What has probably happened is that some of the fat gain has accumulated around the organs and through the liver, causing it to struggle (think of fois gras geese)
If that person loses weight (and the diabetes hasn't caused too much permanent damage) then they may dip down below their personal fat threshold - and their diabetes may 'reverse'.
Of course it is far more complicated than that. Not all type 2 diabetes is caused by a fatty liver. People's personal fat thresholds change over time (may be your PFT was 14 stone when you were young and fit, but maybe it drops to 11 stone by the time you are 50 yrs), muscle, fitness, carb intake, alcohol usage are likely to influence your PFT. Everyone has a different PFT - someone might develop type 2 at 10 stone, someone else might not develop it at 40 stone.
It's obviously complicated and very variable but hopefully that gives you a rough idea.