Navigate to the Trends tab using the bottom console, then click Manage Charts at the bottom of your screen, or use the menu in the top right corner of the trends tab to manage your chart preferences.
Tap Create New Chart at the bottom of the screen to add a new chart to your library.
You can add up to two different unit types (plotted on the left and right y-axes) and up to two different data series.
You can choose two items to plot on a graph, including any combination of biometrics, nutrients and nutrition scores.
Once you have saved your custom chart, you can toggle on or off visibility on your charts page, or even delete the chart altogether.