Europeans are leaner mostly... eat less fatty food or just eat less food.. and some european countries are very cold but people have an active lifestyle so they burn a lot more too... like in switzerland they eat cheese and chocolate all the time but never put on any fat.... u will never see obese people in switzerland like u see in the US. Also I think in the US - food is very tempting.. people tend to eat out a lot more... gay men in the US also focus more on getting bigger - rather than getting leaner and fitter.. they are also obsessed with steroids, supplements and gaining size.... its not easy to gain muscle mass without getting fat around the belly too. I think in UK though the obesity levels are more or less similar to the US... british food is the worst for your health... fish and chips.. bangers & mash.. and the lovely english breakfast...full of 5000 calories.
That said - I dont have a 6 pack.. and dont want one... I find abs very unnatural anyway.