In March of 2010, Congress passed a law requiring calories to be posted on menus of restaurants with twenty or more outlets (https://cspinet.org/sites/default/files/why-menu-fact.pdf ). The question is whether people actually pay attention to nutrition labels and whether it influences their ordering behavior. I interviewed 34 people at McDonald’s and found that 39.39% of restaurant-goers pay attention to the calorie labels when ordering and, for many, it impacts how they order.

One mother explained that calorie labels made her order less for herself and her kids. Even when they buy a hamburger, they will order it without the sauce and ketchup–just the bread. If they order drinks, it has to be either water, tea, or a clear drink–no Coke or Pepsi. Another man responded that it’s not a matter of ordering more or less as a result of nutrition labels, it’s ordering differently. He’s more mindful of ordering and will move to something else that he likes if the calories are too high.

On the flip-side, the majority of respondents, 61.76%, said that they don’t pay attention to the calories listed on the menu. One Korean War veteran, who is 90 years old, said: “I don’t care. If that’s what I want to eat, that’s what I’m going to eat. I don’t care if it’s 10,000 calories. It don’t matter. I’m going through this world once, I’m going to eat what I want to eat.” Another man responded that he knows exactly what he needs to do to lose weight, but, in total honesty, he doesn’t pay attention to how many calories he eats. Still another man said that he knows it’s bad for him, but he doesn’t pay attention to calories either.

The National Health and Nutrition Examination Survey, published by the Center for Disease Control, sheds additional light on this subject. Figure 1, below, shows what percentage of people between 2013 and 2016 used or did not use the nutrition information at restaurants. In 2013-2014, 43.24% of respondents said that they used nutrition information in a restaurant, which is just a few percentage points higher than my informal survey at McDonald’s.

Figure 1.  Did You Use Nutrition Information at the Restaurant?
Year	Used Nutrition Information In a Restaurant	Did Not Use Nutrition Information at Restaurant
2013-2014	43.24%	56.76%
2015-2016	44.89%	55.11%

The next question is whether paying attention to nutrition labels impacts health outcomes. The question I tackle is whether nutrition labels help customers control their weight. Figure 2, below, shows that, between 2013-2014, respondents who use nutritional labels were 5.29 pounds lower than those who did not. And, between 2015-2016, this difference increased to 8.97 pounds. So, at first glance, nutrition labels seem to be making a difference.

Figure 2.  Average Weight of Respondents who Did and Did Not Use Nutrition Lables at Restaurants
Year	Average Weight if Used Nutrition Information at Restaurant	Average Weight if Did Not Use Nutrition Information at Restaurant	Difference
2013-2014	176.4247	181.7158	5.2911
2015-2016	174.5644	183.5336	8.9692

To test this idea further, I look at how people who indicated they ate every meal at a fast food restaurant over the course of a week (21 meals) experienced weight changes before and after March 2010. Chart 1, below, shows that the average weight of people who ate all of their meals at a fast food restaurant fell after 2010. For comparison, I included the average weight of people who ate zero meals outside the house. The idea is that, for this latter group of people, the nutrition labels law should not impact them. This insight is supported by Chart 1, which shows that the average weight of people who ate all their meals at home did not change perceptibly after 2010.

Finally, I use a differences-in-differences strategy to tease out the impact of the March 2010 nutrition label law. The strategy is that, absent the law, the weight of people who ate all their meals at fast food restaurants would resemble the slope of the line of people who ate all their meals prepared at home. But, with the law, the “All Fast Food Meals” respondents diverge from the comparison group, “All Home Prepared Meals.”

I difference out the trend line of the “All Home Prepared Meals,” which is basically flat, from the “All Fast Food Meals” to expose the impact of the March 2010 nutrition law. Figure 3, below, shows that nutrition labels reduced the average weight of people who ate every meal at a fast food restaurant by 6.89 pounds.

Figure 3. Differences-in-Differences
Group	Pre-2010	Post-2010		Difference
Eat at Home Every Meal	169.2981	169.3386		-0.0405
Eat at a Fast Food Restaurant Every Meal	187.48	180.6286		6.8514
Difference	-18.1819	-11.29		-6.8919

This statistical exercise presents an upper bound on how effective nutrition labels at fast food restaurants are because people who eat all their meals at fast food restaurants are most likely to be impacted by the nutrition label law. A large proportion of people pay attention to nutrition labels and it impacts how they order. This is borne out in the numbers on how much people weigh.