Couldn't find the original article, but here is another one. Even including most of the population, with all our different bodies, 96% of us fall within a relatively narrow range of calorie requirements. "I've got a slow metabolism" is usually an excuse. You're simply eating too much.
http://examine.com/faq/does-metabolism-vary-between-two-people/
68% of the population falls into the range of 1840-2160kcal daily while 96% of the population is in the range of 1680-2320kcal daily.
Metabolic rate does vary, and technically there could be large variance. However, statistically speaking it is unlikely the variance would apply to you. The majority of the population exists in a range of 200-300kcal from each other and do not possess hugely different metabolic rates.
That said, no one should be made to feel ashamed about their weight. There are ways to discuss this without going "phuck those stupid fatties!"