Step 6 The big idea · 8 min
The carb vs fat switch
Drag the dials and watch your body choose which fuel to burn. The "fat-burning zone", explained.
You always burn a blend of carbs and fat at once. What changes is the recipe. Three things tip it: how hard you work, whether you recently ate carbs, and how long you've been going. Try it.
Burning now
Crossing over
Carbs 53%
Fat 47%
Muscle 5.3 kcal/min
0.28 g/min fat 0.70 g/min carbs
Carbs have taken the lead (53%). Push harder and fat almost drops out.
Effort easy
Drag to explore
How hard you are working, from sitting still to all-out.
Recent carbs snack
A carby meal raises insulin, which puts fat-burning on pause.
Time elapsed 12 min
The longer you go, the more glycogen drains and fat steps back in.
How the mix shifts with effort
● fat ● carbs