A reader wanted a pie chart to help track weight loss. She acknowledged that pie charts aren’t the best way to show data, and in fact a timeline shows progress over time well.
But there is a certain charm in, say, a pizza pie chart, which shows the current progress by eating away at the pizza. To compare two values, I pie chart is not totally terrible, so I’ve put together a simple protocol here.
The data is simple. Cell B1 contains the weight loss goal, cell B2 holds the current weight lost, and cell B3 has a formula that shows the difference, =B1-B2.
Select A2:B3 and create a pie chart. It looks like this. For illustration purposes I’ve shaded the plot area of this chart light yellow, and the chart area light gray. We will use a special fill for the plot area in a moment.
First, remove the colored fills from the chart. The two wedges should have no fill at all. I’ve left black borders on the chart, or it would vanish completely.
Now find a nice picture of a pizza pie (or a chocolate cake or lemon meringue pie). This picture came via Google Images from Taste Test: Pizza Slimdown in Chicago Magazine, who judged this beauty from Spacca Napoli to be the best Margherita pizza in Chicago.
Right click on the plot area (not the chart area or either of the pie sections), choose Format, and where appropriate for your version of Excel, use the picture as the fill pattern for the plot area. In Excel 2003 and earlier, go to the Patterns tab of the Format Plot Area dialog, click the Fill Effects button at the bottom of the Area section, select the Picture tab, click on the Select Picture button, and browse to your image.
The pie fills up the whole image. Add labels to the center of the pie wedges, using a white background instead of transparent, so it shows up among the pizza toppings, and change the fill of the Already Loat segment to a solid color (white in this case).
You may even want to remove the black borders.
As you lose more weight and change the value in cell B2, the “eaten” portion of the pie increases in size.
You could probably use an image editing program to get rid of the very light gray packground in the original picture. For this demonstration I left it unchanged.