# Is a calorie a calorie??



## AChappell (Jun 1, 2011)

Is a calorie a calorie??

A calorie is not a calorie regardless of where it comes from. I used to always argue this from the point of view of a macronutrients and the biological functions they perform.

Carbohydrates are primarily used as an energy source as are fats, while protein is largely used as the building blocks in our tissues. This however is a massive oversimplification as any biologist will tell you. Lipids, amino acids and sugars are used in almost everything as structural components from DNA to hormones, to cell membranes and membrane receptors. They perform very different roles so can't be the same. This however never really addressed the question of energy, but it was usually enough for people to reconsider that a calorie was in fact not just a calorie and that macronutients are probably different so shouldn't be considered one in the same.

However after some reading I now realise a massive over site on my part was that after the consumption of any meal there's always a degree of diet induced thermogenesis (DIT). That is a certain amount of energy is loss as heat during the digestion process. The amount of energy lost from each macronutrient is different. The amount of lost is roughly as follows 20-30% protein, 6- 8% in carbohydrates and 2-3% in fat.

This older study by Westerterp displays this nicely, where two isocalorifically matched diets were compared with different amounts of protein fat and carbohydrate. The paper is below for anyone interested

Briefly researchers found a diet higher in protein and carbohydrate resulted in greater DIT compared to the high fat diet. Thus proving that a calorie is in fact not just a calorie

http://www.ncbi.nlm.nih.gov/pubmed/10193874

Diet induced thermogenesis measured over 24h in a respiration chamber: effect of diet composition.


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## EXTREME (Aug 5, 2005)

There is no attachment Mushy.

I'd like to debate this with you but in language everyone will understand. Your meaning is not that clear in your original post.


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## AChappell (Jun 1, 2011)

A gram of fat is worth 9Kcal, protein 4Kcal and carbohydrate 3.75kcal per gram.

Some people argue that it doesn't matter where your calories come from a calorie is a calorie. For example 100kcals of energy from protein is the same as 100kcals of energy from fat or carbohydrate. Despite these macronutrients performing very different functions in the body.

The above post discusses the effect of diet induced thermogenesis (DIT). As you eat a certain amount of energy is lost, or to look at it from another angle, there is an energy cost to digest food.

So for protein you might lose around 20-30kcals from the 100kcals you started with. Carbohydrates you would lose around 2-9kcals from the 100kcal start and fats you'd lose the least at around 2-3kcals per 100kcal.


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## Neil R (Oct 29, 2006)

Have you been talking to an IIFYM advocate by any chance?? :lol:


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## RSteele (Aug 7, 2013)

IIFYM - the best diet to follow if you want to justify eating that McDonalds every week...


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## AChappell (Jun 1, 2011)

This isn't necessarily a dig at IIYM dieting I think the consequences are far broader than that dieting approach alone. I'm not really big on IIFYM though RSteele, I've posted enough about it in the past. Agree'd it shouldn't be used as justification to eat junk food.


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## ronnie cutler (Dec 29, 2009)

I believe in empty calories

1000 cals of fat and sugar do not have the same effect as 1000 cals of protein!

Big difference on how your body digests and uses these very different calories!

using Tapatalk for iPhone


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## Tom84 (Dec 12, 2005)

AChappell said:


> Is a calorie a calorie??
> 
> A calorie is not a calorie regardless of where it comes from. I used to always argue this from the point of view of a macronutrients and the biological functions they perform.
> 
> ...


For the most part isn't the high level point here just completely agreed upon?

For example - If I consume 3000 cal per day solely from coca cola, I'd have markedly different physical and biological reactions, than if I drank 300cal in protein shakes, or 3000cal from P/C/F sources.

I assume we are all agreed on the point.

Very interesting on the DIT point though, that I didn't know, and this adds further weight to the perhaps more obvious macronutrient argument


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## EXTREME (Aug 5, 2005)

Protein is by far the hardest source to digest and so causes/suffers the greatest loss during digestion meaning you're getting less than you thought, then carbs than fats which are easiest.

I don't believe a "calorie is a calorie" but I do think people get too concerned with it all, especially if they're like that all the time and not preparing for a show.

I believe that the biggest controlling factor is a genetic one and that is how your body produces and responds to insulin


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