The manner of processing of carbs or fats for protein for that matter has little relation to this point. There is not a single study in the long-term that proves any difference in terms of weight gain as it relates to this point, keeping CALORIE INTAKE THE SAME, and critical evaluation proves it time and time again.
There have been some short term studies that have indicated differences. the long-term research is finally getting funded. The big research dollars for a few decades now have been spent on low-fat, low calorie diets, and on dietary fat and heart disease. I suspect that when the research is finally done, the "calories are all that matter" idea won't fare so well.
And just looking at the American population over the past forty years is enough to start to be suspicious of the idea that changing macronutrient levels don't affect weight loss. In that time span, our macronutrient percentages have changed as a population - dietary fat has decreased as a percentage, dietary carbohydrates have increased (and it's suggestive that much of the increase in carb intake has been the most highly processed carbs, sugar and high fructose corn syrup). So has our weight, as well as diabetes levels. None of this is proof of anything, but it is suggestive enough to warrant more research.
I didn't mention activity in this sentence, because it's not what I was focusing on and was already well-known from my posts.
One of the problems with focusing only on calories when talking about weight loss is that it vastly oversimplifies the subject. The endgame of that approach is that a calorie is a calorie. It doesn't address the question of whether the metanutrients DO have an effect, not only on immediate weight loss but on longer term retention of the results. It doesn't address how the different metanutrients affect hunger/satiety, or energy/lethargy. Do carbs stimulate overeating? Does fat? Do they differentially affect spikes in the body's ability to smoothly supply energy, or create spikes? Do they differentially encourage or discourage activity levels? All those factors could affect or drive hunger and caloric intake. Which ones create the best chance of successful calorie restriction? Are they all exactly the same in that regard?
Those questions have a direct bearing on weight loss. The research hasn't been done. To say they don't matter, aren't relevant to weight loss or gain, because the research hasn't been done, is some mighty premature decision making.
The irony is, nutrition science has been dominated for at least forty years by two ideas: A calorie is a calorie - what is relevant to weight loss/gain is nothing more than caloric intake. And to cut our weight, we need to cut dietary fat. Think about it. Those two contradict each other. The scientific world has been stepping on its own tail with two contradictory truisms. And the research results over the past forty years, driven by those two ideas, have been uneven and contradictory while ignoring any competing ideas. And one thing that most researchers acknowledge is that calorie restriction doesn't seem to work - it can for some people, but it fails on a research level pretty consistently. If that's all that matters for weight loss, it's fair to ask why it isn't working.
Further, your argument is predicated on the argument that insulin is the only hormone that is released that deals with fat storage. Leptin and ghrelin are also released and have more impact on how fat is stored than insulin.
Yes, both are key players in energy storage/utilization. And although the research is still pretty young on both, there are indications that both are regulated and controlled to at least some extent by insulin.
Your confusing the issue of storage of fat versus the manner in which a calorie is processed.
My point (and we may just have to disagree on this) is that there is enough research out there, as well as historical data, to suspect that the issue of fat storage/utilization is more relevant to what we understand about weight loss and gain than you seem to be claiming.
So is being excessively thin and the definitions of obesity have been constantly changing over time. There is no agreed upon definition of what constitutes obesity.
Well, the average man and woman are both about 25 pounds heavier than they were in 1960. No matter your definition of obesity, that's a significant gain. It works out to an increase in BMI of about a 12% for both men and women.