Predictably, this was all very simplistic and could be summarised as:
KH: "Fat people simply need to exercise more self control and exercise more".
Overweight interviewees: "You don't understand why I'm fat, how dare you say being my weight is unhealthy and anyway, it's easy for you to lose weight".
There was only lip service paid to the real issue, which is why some people overeat and don't do sufficient.
Whilst I agree that quickly gained weight is probably easier to lose than weight accumulated over years, I don't see any evidence that KH has an especially high metabolism. I read that her typical day's diet consists of bran flakes for breakfast, a tuna sandwich for lunch and a homemade meal such as curry or roast for dinner - no snacks. She also runs for an hour, three times a week. I'm sure most people would lose weight or maintain a low weight on such a regime.