Come on, be honest with yourself.
Studies show, statistically speaking, you probably won't. Only 15 percent of the population cares. With that there big asterisk on who you are, demographically speaking, with a large emphasis on how old are you. Even then, only a conscious effort to change behavior would make a difference. At least the information is now getting out there for those to take advantage of it.
All of this is speaking in generalities, of course, with many exceptions. No matter who you are though, old habits are hard to break. This is ever more important because the scientists tells us that it is diet, not exercise (its still important too), that is key to being healthy.
Each generation is raised with a different set of values based on the major life experiences of their parents. As such, each generation reacts differently when receiving new information. The Silent Generation is about self-sacrifice - they grew up in the Great Depression and World War 2. Everything needs to be stretched as far as it can go, and then some. The Boomers are grew up in a time of plenty. There were trials and tribulations without a doubt, but for the most part it was a time of entitlement where traditional values were redefined and reasserted. Generation X came along after them and made it about defining yourself as an individual, often rebelling against their parents notions of traditional values and therefore many countercultures arose. Then came the Millennials, whose familiarity with communications technologies and media came to define them: a TV in every bedroom, a laptop in every backpack, and a cellphone in every pocket.
With this in mind, what did studies find when it comes to posting calorie counts on menus? Not much, but your age may make a difference. The Grandparents (the Silent Generation) will maximize the bang for their buck by buying more calories for less money. The older parents (The Boomers) will buy whatever they feel like buying and ignore the calorie counts altogether. The young adults (Millenials) will reduce their calorie consumption and buy healthier food. More of this generation notices the calorie counts. A healtheir body is a better media image. The middle adults (Generation X) is caught somewhere in between their older and younger peers.
When the data is looked at from a distance, it seems that everyone's buying choices cancel each other out and impact looks nil. But when the numbers are broken down by age, it tells a story of the younger you are the more likely you are to adjust your eating habits in a healthier way when you receive information that let's you make that type of decision.
If history is any type of indicator, then I would not expect an immediate impact on the bottom line of McDonald's when posting their calorie counts. But in ten, twenty, thirty years from now, it will make quite the difference. McDonald's will have to adjust or find themselves going the way of the dodo.
Writers note: I'll admit that, though I believe this to be true based off the information out there, there is still a fair bit of projecture in this piece. Studies have been mixed and incomplete at best.