Download Using TreeMaps to explore food diaries

Susan Campbell
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Using TreeMaps to explore food diaries
Keeping a food diary is a fairly popular way of monitoring food consumption, either before
starting a weight-loss diet or during a diet to measure progress. I chose to use a food diary for
this project to explore the patterns that can be found in the composition of food and, secondarily,
to see if there were any ideas I could get about how to improve my own eating habits. The tool
I used was a TreeMap (I used the implementation freely available on the HCIL website), because
I wanted to see how the different items contributed to the total.
To generate the data file for this exercise, I recorded what I ate for a period of two weeks, which
also happened to be the duration of the assignment. The data collected included quantity by
weight, calories, grams of fat, grams of protein, and grams of carbohydrate. Some of the
numbers were fudged, because exact data are difficult to come by. From the items I recorded, I
calculated the percentage of weight in a given item taken up by each source of nutrition, and the
number of calories per gram of food item.
My first example is the most obvious insight gained from this exercise: I drink a lot of coffee.
This display confirms what I already know about my eating habits, but I wasn’t quite aware that
some days I consume more coffee than solid food.
Figure 1: The black box in the upper left-hand corner is all coffee. Here, the hierarchy is by food item
category. The size of each box depends on quantity, and color is calories per gram, which goes from 0
(black) for coffee to 8 (red) for olive oil, butter, and chocolate.
Susan Campbell
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Static information tools, such as a tabular display in Microsoft Excel, can give a general idea of,
for instance, the number of calories one has consumed in a week or over a period of time. The
overhead involved in performing calculations on this data repeatedly, however, is considerable,
as days do not necessarily include the same number of items. From Microsoft Excel’s SUM
function, I could determine that I was getting about 1800 calories a day, which seems reasonable
for someone my age and height, if a little low. Unfortunately, what the SUM function and some
judicious division in Excel couldn’t tell me without a lot of work was that I eat a lot more during
the week than I do on the weekends. I also ate a little too much Valentine’s Day candy and
baked goods, as that bar has more calories per quantity of food than any other day in the twoweek period.
Figure 2: The two narrow bars in the middle are Saturday and Sunday. The smallest two boxes are about
1000 calories each. The hierarchy here is by day, then by date, and the leaf nodes are obscured. The size
of the boxes refers to the number of calories consumed each day, and the color represents the number of
calories per gram of food. The orange outlier here is Valentine’s Day, where I apparently ate a few too
many truffles.
Susan Campbell
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My initial hypothesis for why the number of calories for Valentine’s Day was so high had to do
with chocolate truffles, but it turns out that banana bread with lots of butter was also a highcalorie, high-fat contributor. A lot of the calories in my diet come from fat, though the number is
well under the USDA’s 30% guideline (one should get no more than 30% of one’s calories from
fat).
Figure 3: The red spots show foods that are almost pure fat. The hierarchy is by day of the week, then by
date. Box size is determined by number of calories, and the colors are percentages of fat in each food, with
black representing 0 and red 95%. A fair amount of my caloric and fat intake also appears to come from
lunch at the food court, but I have not systematically explored that observation.
One of the problems with dealing with nutritional data is that it is difficult to find accepted
guidelines for eating. The new food pyramid is not widely available, and still depends on the
concept of a “serving” of a particular food, which is ill-defined. The number of calories an adult
male is supposed to get in a day is 2000, but other guidelines for calorie consumption are difficult
to find and often biased in favor of a particular fad diet.
Susan Campbell
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I was worried that I was eating a lot of high-calorie foods, but checking the calorie density of
food versus how much of it I ate does not bear that out; the foods I ate the most of tended to be
fairly low calorie, and I did not eat a lot of high-calorie food.
Figure 4: Reversing the diagram, it turns out that I tend to eat the most of things that are relatively low in
calories per gram of food. The hierarchy here is the general category of food item. Size in this diagram
refers to the number of calories per gram of food, while color is the quantity I ate.
This example may seem trivial – I ate fairly healthily in this two-week period, though have
revealed that I am a grad student with a weakness for pizza, especially the free kind. It turns
out that I should probably eat less pure fat and balance out what I eat more carefully so that I
do not forget to eat on the weekends.
More generally, as part of an application to track food consumption and food cost, this kind of
visualization could supplement the traditional food diary by showing users how the food they eat
fits together and what of the food they eat is contributing the most calories to their diet. The
data could be made more precise with recipe integration, but the general idea remains the same
even with a little fudging of exact figures.