In one sentence
The total glucose exposure above your pre-meal level across the two hours after a meal, the area under the bump, which counts how long the rise lasted as well as how high it went.
Why it matters
A tall thin spike and a low wide hump can have the same peak and very different meanings; the area tells them apart. It is the measure the research uses for a meal's glycemic response: Zeevi's 800-person study and the British twin study both scored meals on the two-hour incremental area (Zeevi 2015; Berry 2020), and it is the figure VT's meal comparisons are ranked on. Because it integrates 24 readings rather than picking one, it is also steadier than the peak from one day to the next.
What moves it
Everything that moves the peak, plus how quickly the rise came down: a meal with fat slows the rise and extends it, so its area can be larger than its modest peak suggests; a meal followed by a walk comes down faster and its area shrinks more than its peak does. Meal size matters more here than for the peak, because a large meal keeps glucose up for longer.
How to measure it well
As for the peak: log at the start, with what was in it, and repeat the meal. If a second meal or a snack falls inside the two hours, VT marks the window as overlapped and the figure as unreliable; a test meal needs two clear hours.
How Vitality Tracker uses it
The ranking figure of the meal library and the basis of the meal comparison, which puts the same meal's repeats side by side and two meals against each other; shown with the peak and the dip. Not a Vitality Score input.
How far to trust the number
Calculated from measured readings; the most reliable of the three meal figures for a single sitting, and reliable for a meal once it has repeated. Its absolute value depends on the sensor and the site, so it compares within your own record, not with anyone else's.
Sources
- Zeevi D, et al. Cell 2015;163:1079–94. doi:10.1016/j.cell.2015.11.001
- Berry SE, et al. Nat Med 2020;26:964–73. doi:10.1038/s41591-020-0934-0
- Wyatt P, et al. Postprandial glycaemic dips predict appetite and energy intake in healthy individuals. Nat Metab 2021;3:523–9. doi:10.1038/s42255-021-00383-x.