# Is there a limit to calorie density in food?

**URL:** <https://boards.straightdope.com/t/is-there-a-limit-to-calorie-density-in-food/490239>\
**Category:** Factual Questions\
**Created:** [March 21, 2009, 4:03am UTC](https://boards.straightdope.com/t/is-there-a-limit-to-calorie-density-in-food/490239 "2009-03-21T04:03:33Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\
**Post date:** [March 23, 2009, 3:17pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-calorie-density-in-food/490239/21 "2009-03-23T15:17:27Z")

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Those posphonate groups will hydrolyze pretty easily with stomach acid. All of the hydrolysis reactions are [highly exergonic](http://en.wikipedia.org/wiki/High_energy_phosphate). In the cell, the pH and environment is not very extreme so ATP can last, but I find it very unlikely that ATP can survive stomach acid. The only way ATP could survive is if there were some unforseen kinetic barrier like sterics.

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**Author:** ![Bad\_Astronaut](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Bad\_Astronaut](https://boards.straightdope.com/u/Bad_Astronaut)\
**Post date:** [March 24, 2009, 8:48pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-calorie-density-in-food/490239/22 "2009-03-24T20:48:58Z")

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Aren’t calories measured by burning the item and recording the heat produced?

In that case something like C4 would have a very high caloric density.

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