I am honour bound to point out, though, that although the Minnesota experiment 'victims' were eating 1570 calories - they were all men, in which case that's considerably fewer than the recommended daily calorie allowance for men. I would hate to think that female Bootcampers thought we were recommending that daily amount.
Like @StuntNun, it's the not counting or weighing everything that is important to me. Indeed it's why I first thought up Bootcamp! 
However, you do need to be aware of what you're putting in your mouth, and the carb and calorie 'load' that you're consuming.
In general, in the UK, we all consume far too many calories (not even thinking about the carbs). Allegedly, the size of dinner plates has increased over the years, so now we eat from much bigger plates - which means that we fill our plates with more food without even thinking about it.
We eat out or have takeaways a lot more - when I was growing up, in the 60s and 70s, takeaways were an occasional treat - most likely fish and chips - and going out for a meal was definitely reserved for a special occasion.
Think, too, of how many times a day you drink tea/coffee - and/or go to Starbucks/Costa/Caffe Nero etc for a takeaway coffee? Chance are, there's a biscuit alongside that tea/coffee, if not a muffin or a cupcake or a brownie.
We also think that we need to snack during the day. I read a lot of posts here where posters are asking what snacks they should plan to include in their day. And even if we think we're choosing healthy snacks, next time you're in the checkout queue alongside all those Graze packs, just have a look at the ingredients - the calories, the sugar and the carbs (as well as whatever else goes in them!)
My point here is that we have become used to eating far more calories and carbs than we need.
Whilst on Bootcamp we're cutting the carbs significantly, and the mantra is 'you don't need to count calories', I think it's still a very valid point that we should all, from time to time, step back and look at what we're eating.
The article I linked to - whilst it had a rather hostile tone of voice - does make a good point, that we often consume rather more than we think we do. Not that we're lying to ourselves, rather that we forget, or deny it.
How many cups of coffee or tea do we have during the day that we don't bother to count? That milk all adds up!
This post is aimed at all of us - not just those who are struggling to lose, but it was inspired by @AthestaneTheUnready and @LeapinLizards.
Calories do matter overall - and as you get within a stone or so of your desired target, you will have to start giving them consideration. But even for the rest of us, we do need to be mindful of what we're eating. Taking carbs out of the diet doesn't mean that we can just pile our plates high!