Disagreeing is hardly being rude. But, considering that we have an obesity problem in America, despite caloric intake being an average of 2000 calories per day, I'll stand by my initial statement.
No, its actually closer to 4,000 per day (I think it's around 3,700). Not to mention that a large proportion of those calories come from high sugar, high fat, highly processed food sources. Couple this to the lack of exercise and sedentary lifestyles and that's where your obesity crisis comes from.
The idea that rare metabolic diseases are to blame for the growing obesity epidemic is preposterous. Sure, hypothyroidism and its related syndromes can lead to weight gain in individuals despite them not consuming vast numbers of calories. However in these people being a couple of pounds overweight may be the result; being obese is not. Plus, most cases of hypothyroidism can be treated with medication and simple dietary and lifestyle alterations.
The simple fact is that no human body (perhaps barring the rarest of diseases and I only include this as a disclaimer) is capable of generating vast quantities of fat mass,
new living tissue, to point of reaching obesity (i.e. over 25% bodyfat in men, 30% in women) without overconsumption of calories. It is as simple as that.