> For the complete documentation index, see [llms.txt](https://riduck.gitbook.io/riduck-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://riduck.gitbook.io/riduck-guide/english/browse/metabolism.md).

# Metabolism

## Metabolism Chart

<figure><img src="/files/KOTS0y3ER3OG7awbxliX" alt=""><figcaption></figcaption></figure>

The metabolism chart estimates your reliance on fat and carbohydrates for energy, depending on exercise intensity.

{% hint style="info" %}
Humand use different energy sources depending on exercise intensity. At low intensity, fat is primarily utilized, while at higher intensity, carbohydrates become the main source.
{% endhint %}

* FATMAX: This is the point where fat oxidation (utilization) is most efficient. By maintaining power within the yellow zone (FATMAX), you can train effectively to reach your goals.
* Duration: The estimated time that you can sustain the power at the FATMAX point.
* TSS (Training Stress Score): The estimated training stress score achievable if power is maintained at the FATMAX level for the specified duration.