Monday, January 7, 2013

Is there good and bad fast-food?

Since the Christmas feast days are now over, this blog post continues the series on the nutritional characteristics of modern fast-food, which started with the Network analysis of McDonald's fast-food.

Men's Health magazine has produced a list of what it considers to be The 10 Worst Fast Food Meals in the USA. They chose one meal (usually a combination of several menu items) from each of ten different fast-food chains, which they considered to be extreme meals based on their nutritional characteristics. To counter-balance this list, they also chose another meal combination from each chain that they considered to be much "better for you".

For each of these 20 meals the magazine provided data on four of the nutritional characteristics: Calories, Fat, Saturated fat, and Sodium (salt). I have analyzed these data in the same manner as before: I standardized the data by expressing them as a percent of the officially recommended daily value based on a 2,000 calorie diet, then calculated a NeighborNet network based on manhattan distances.

The resulting network is shown in the figure. I have coloured the ten allegedly "better for you" meals alternately in green or blue, with all of the "worse for you" meals in black. Meals that are closely connected in the network are similar to each other based on their nutritional characteristics, and those that are further apart are progressively more different from each other.

Clearly, the "worst food" meals differ greatly from each others in their nutritional characteristics, while the other ten meals do not. In other words, there is a single clear concept of what is "good for you" but many different ideas about what is "bad for you" (or many ways in which the food can be unhealthy).

Furthermore, the "worst food" meals vary in their relationship to the better meals, with Long John Silver's Fish Combo Basket being rather similar to the better items, and both KFC's Half Spicy Crispy Chicken Meal and Burger King's Large Triple Whopper being at the extreme far end of the graph. Indeed, the "worst food" meals form a gradient of increasingly extreme nutritional characteristics: the calories, fat and saturated fat all increase from bottom to top in the network, and sodium increases from left to right.

The sodium change applies in the better meals, as well, with Quizno's Roadhouse Steak Sammies having more salt than the other nine meals in that group.

So, it seems to me that the fast-food chains are having a harder time creating unhealthy fish meals than they are creating unhealthy chicken and beef meals. However, this may just be lack of effort on their part, because the Tuna Melts with Cheetos meal is certainly pretty extreme.

Anyway, you now know which meals to target should you wish to send yourself into an early grave.

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