# Function: gutRetentionTime()

[**lifecycle-kit**](https://jonbogaty.com/lifecycle-kit/api/readme/index.md)

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[lifecycle-kit](https://jonbogaty.com/lifecycle-kit/api/readme/index.md) / [bio-laws](https://jonbogaty.com/lifecycle-kit/api/bio-laws/readme/index.md) / gutRetentionTime


# Function: gutRetentionTime() {#function-gutretentiontime}


> **gutRetentionTime**(`massKg`): `number`

Defined in: [bio-laws/lifeHistory.ts:212](https://github.com/jbcom/lifecycle-kit/blob/074e4e7b8038d3e2de9eb44c4b5b5aee0ef02b48/src/bio-laws/lifeHistory.ts#L212)

Mean gut retention time, in hours.

Source: Karasov, W.H. & Douglas, A.E. (2013). "Comparative Digestive
Physiology." Comprehensive Physiology, 3(2), 741-783.

  MRT ∝ M^0.27

Bigger animals hold food longer, which is why they can eat worse food. A
small creature must eat richly and often; this is the law that says so.


## Parameters {#parameters}



### massKg {#masskg}


`number`


## Returns {#returns}


`number`