That really doesn't make sense..
Sure it does. Be mindful that weight is not usually the result of any actual effort or attention. It's usually just where somebody finds him/herself due to a lack of attention.
People with low BMIs are less likely to have weight as something on their mind. Whereas, people with higher BMIs are motivated to lose the weight and therefore more likely to be using a strategy to do so, one of which is monitoring calorie intake. To put this another way: calorie counting is dieting, thin people don't need to diet, ergo thin people are less likely to be calorie counting. All things being equal, meaning there will be outliers such as anorexics who are simultaneously thin and calorie obsessed.
The point being that BMI is not a measure of attention or effort directed to weight management. This is the disconnect I'm trying to get people to wrap their heads around. We can't look at somebody and determine the amount of weight management effort by their BMI.
Calorie counting
is positively associated with weight
loss and dieting. So if you know a person lost weight this year, or at least attempted to while dieting, they are more likely to have been calorie counting than somebody who didn't, regardless of current BMI.
I'll see if I can locate some examples, but the research that directly relates to this is called 'adherence to self monitoring'. I recall that BMI is positively correlated with all types of self monitoring behaviors, which include calorie counting, weighing oneself, keeping a food journal, &c. The corollary is that when people lose weight they stop self-monitoring, which is a strong candidate cause for yo-yo. Successful maintenance is rare because thin people pay less attention to their weight management. Less motivation probably.
There's a revival in interest in studying self-monitoring behavior with the emergence of fitness bands. If nothing else, Marketing departments want to know whether demographics can predict usage, and whether results affect usage. Turns out low BMI people have less interest in self monitoring products, and also use them for a shorter time. (most apps have a dropoff curve, something like 10% usage after a month - this is not unique for health apps).
Something else that surprised me: higher BMI subjects are less likely to use what skeptics would call 'quackery' techniques for weight management. That is to say, for example, that they are more likely to be calorie counters versus fad dieters. I haven't seen any good research to explain this, but my theory is that higher BMI people have more dieting experience and have learned through trial and error that calorie counting has better results. eg: [
Differences in Health-Related Behaviors and Body Mass Index Risk Categories in African American Women in College]
