Any dieticians out there – what are calories?

[Robin GrahamParticipant @robingraham42208]

It's perhaps a daft question but it's been bugging me and I haven't so far found an answer.

If you wanted to measure the 'calorific value' of, say, a portion of bacon you'd bung it in a bomb calorimeter, fill it with compressed oxygen and measure the energy released by complete combustion.

Would that be the same as the 'calories per portion' listed on the packet? Obviously what we excrete can be burned and release more energy. Do the numbers on the packets refer to total energy (referred to the baseline of completely oxidised bacon) or to energy released by metabolism? Someone must know!

Robin

[Robin GrahamParticipant @robingraham42208]

[Cabinet EnforcerParticipant @cabinetenforcer]

Fourth link on my google search, your google-fu is weak Robin-san.

**LINK**

Edited By Cabinet Enforcer on 13/07/2023 01:34:20

Edited By Cabinet Enforcer on 13/07/2023 01:34:38

[Kiwi BlokeParticipant @kiwibloke62605]

Food calories only really mean something to dieticians. Conversion factor: 1 calorie = $ n

[Michael GilliganParticipant @michaelgilligan61133]

The page linked by Cabinet Enforcer is spot-on [let’s just accept the American spelling], and it includes the important fact that [quote] A food calorie is actually a “kilocalorie” …. [/quote]

MichaelG.

Edited By Michael Gilligan on 13/07/2023 05:28:36

[Chris MateParticipant @chrismate31303]

My question would be if you measure it in any other way than your body deals with it in general as a specie, or individually, where your body is a chemical, electrical affair, how would that be correct for you as a person eating different foods and having different effects on different people at different ages and level of fitness and physical activity in your life-? can you eat and drink anything including alcohol and maintain a good PH in your body-?

[Gerard O’TooleParticipant @gerardotoole60348]

Chris, a good explanation of pH buffering of the body is here

Carbonic acid, respiration and renal function all work to maintain correct pH ( about 7.4 )

[Martin ConnellyParticipant @martinconnelly55370]

Funnily enough I was looking at this YouTube video regarding this subject yesterday https://youtu.be/aD7y03rDmFE

The Biggest Lie in Medicine

It has always struck me as crazy that a claim can be made that peanuts (for example) contain as much as, or more than, the same amount of protein as a beef steak so you should eat peanuts instead of steak. A beef steak is easy to digest whereas peanuts are hard/impossible to digest unless they are ground to a fine paste. A large chunk of peanuts must pass through the gut (same as sweetcorn) due to the indigestible cellulose outer shell that the human body cannot digest. Eat enough and you will find out exactly how well these cellulose capsules can pass through you.

As such a lot of experiments regarding the fat, sugar or protein content of foods needs to be taken with a pinch of salt (ha ha) as they do not reflect the body's processes used to extract these nutrients. Even the things you eat in combination makes a difference. Many things we need in out diet are fat soluble and so need to be eaten in a meal that includes suitable fats for it to be absorbed in the gut. An example of something that needs the correct combination of foods is iron, to be absorbed easily you need vitamin C in your diet to avoid anaemia.

Martin C

[not done it yetParticipant @notdoneityet]

Clues:

There are some that burn dried turds for the energy content?

From a newspaper column (Mirror, back in ‘21):

‘A kilogram of cow poo can produce enough electricity to power a vacuum cleaner for five hours – so dairy cooperative Arla's herd of 460,000 could fuel 1.2 million UK homes‘

Chewing on coal wouldn’t make us fat?

 

A calorie is 4.18 Joules, in sensible SI Units.

Edited By not done it yet on 13/07/2023 08:14:11

[Michael GilliganParticipant @michaelgilligan61133]

As an aside … my Human Biology professor assured us that [aside from issues relating to roughage and allergies] a diet of Eggs and Guinness would sustain the human body quite effectively.

MichaelG.

[VicParticipant @vic]

Posted by Martin Connelly on 13/07/2023 08:03:52:

Funnily enough I was looking at this YouTube video regarding this subject yesterday https://youtu.be/aD7y03rDmFE

The Biggest Lie in Medicine

Martin C

I saw that video a little while ago. Another one I saw said that it’s not just the amount of food you eat but how you eat it that influences whether you will gain or lose weight. It really isn’t as simple as calories in calories out as we’ve been led to believe.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Vic on 13/07/2023 08:46:37:

.

It really isn’t as simple as calories in calories out as we’ve been led to believe.

.

Shock, Horror … the ‘experts’ who advise us have simply picked up a few catchy phrases from published papers and recite them as Catechism [without much actual understanding].

If you want an extreme example of this, consider the scare-mongering around “ Body Mass Index”

MichaelG.

[Martin KyteParticipant @martinkyte99762]

1 kCal = 4.18 kJ

[SillyOldDufferModerator @sillyoldduffer]

Well, a calorie (note small 'c' ) is the amount of energy needed to raise 1 gram of water by 1°C. This is a tiny amount of energy, so dieticians use big 'C' calories, which is the amount of energy needed to raise 1 kilogram of water by 1°C.

As Robin said Calories are measured in a Bomb Calorimeter. This consists of a sealed vessel of known weight and material, within which the foodstuff is burned in an excess of Oxygen. The before and after ignition temperatures allow the energy released by combustion to be measured accurately.

Obviously this is not how animal digestive systems work, but the calorimeter gives the maximum number of Calories available if the animal could recover all of them. Species have adapted to recover energy from different foodstuffs. Cow stomachs have four compartments which allow them to digest grass, mostly cellulose, which humans cannot digest at all – it passes straight through. Cows can't fully digest herbage either, which is why cow poo can be dried and burnt.

Although human digestive conversion efficiency is difficult to measure accurately, it's well known that we can extract almost all the energy available from certain foodstuffs, especially Sugars and Fats. As we evolved from hunter gatherers who needed a lot of energy to find food, and often went hungry, we are configured to put on weight in times of plenty, and burn it off later. This causes severe problems to modern man who mostly sits about scoffing an unlimited supply of crisps, Mars Bars, Coca Cola, Alcohol, and Steak and Chips. These are high Calorie foods in a Calorimeter and the human stomach, just the job before the winter famine starts, but we all get fat when there is no famine. Vegetables contain fewer Calories and are digested less efficiently, so we're unlikely to get fat on them. They contain trace minerals, vitamins, and roughage essential to our Biology – digestion isn't just about Calories.

Humans are unique in that we're the only species that can convert inedible food into something we can eat. Cooking, fermentation, dissolving, distillation etc. These processes are also good at removing toxins and killing bacteria. On the downside, processing often removes wanted minerals, roughage and vitamins as well, and it's not unusual for them to be chemically restored.

Digestion is complicated and still not fully understood. To avoid becoming a diabetic slob, it's best to cut back on high-Calorie foods, but Calories are only one indicator. More recently, British ready meals have started carrying a colour code. Trouble is I like food where Energy, Saturates (Fat), Sugar, and Salt are all code RED, and don't enjoy anything that's good for me.

Obesity has become a serious problem in the UK; the NHS is burdened with people who have made themselves ill due to poor lifestyle choices.

When I was younger, Brits used to laugh at Americans because they were all so outrageously fat – not now. Modern Brits are also packed full of sugary goodness…

Dave

Edited By SillyOldDuffer on 13/07/2023 10:23:27

[Martin KyteParticipant @martinkyte99762]

The most important statement in Dave’s post is digestion is not just about calories.
A classic example is lack of vitamin C. Without it your cells cannot make collagen that vital structural molecule.

So the result is your body actually starts to fall apart.

regards Martin

[Kiwi BlokeParticipant @kiwibloke62605]

The calories available for metabolism are those left over after our gut biome has taken its share. And the amount is reduced by many other effects, like transit time, intestinal health, etc., etc. What goes in certainly doesn't all get used. Stop counting calories – eat, drink, and be merry!

[RobinParticipant @robin]

I just type "calories buttered toast" into Google

Robin

[Martin KyteParticipant @martinkyte99762]

Come on guys we are all supposed to be practical people. If your mass is increasing you are either consuming too much (Carbs/Sugars) or you are not burning enough energy. We are our own calorimeter. The packaging info is just there to help.
To go back to BMI could I suggest Bulk Machining Index where the more weight you put on the less you get done in the workshop.

regards Martin

[Neil WyattModerator @neilwyatt]

A practical consideration.

Much effort can be expounded working out what proportion of a calorie in food actually can become body fat compared to how much drops out the other end and how much is burnt in daily metabolism.

The figures aren't actually very useful; the rule of thumb that something under 2,000 kcal a day is what’s needed to maintain a healthy body weight for an average person living an average lifestyle allows for this. You might say "33% of the energy in food I eat is wasted" but that doesn't mean you can eat 3,000 kcal and expect to lose weight!

If you eat a strange diet (say unchewed peanuts or pure lard), are exceptionally tall, small, very active or bed-bound, then obviously it's going to be less helpful.

For what it's worth, I find that at 700 kcal a day I lose about 8 ounces weight a day, but this drops off as I near a sensible weight for my height.

Neil

[Neil WyattModerator @neilwyatt]

Posted by Martin Kyte on 13/07/2023 10:47:22:

Come on guys we are all supposed to be practical people. If your mass is increasing you are either consuming too much (Carbs/Sugars) or you are not burning enough energy. We are our own calorimeter. The packaging info is just there to help.
To go back to BMI could I suggest Bulk Machining Index where the more weight you put on the less you get done in the workshop.

regards Martin

This is true, but I find food labelling does help me choose healthier options. It's amazing what fat/sugar is packed into some products and how many calories are in starchy foods.

P.S. last night I made myself Stilton and broccoli soup with a very large amount of Stilton in it… in case anyone thinks I am a disciplined eater!

[Mike LondonParticipant @mikelondon]

As an aside … my Human Biology professor assured us that [aside from issues relating to roughage and allergies] a diet of Eggs and Guinness would sustain the human body quite effectively.

MichaelG

It would probably be a very lonely existence!

[Chris Pearson 1Participant @chrispearson1]

In answer to the question, I don't think that it matters, but assuming that the calories on the packet are the true version and not some adjusted one, an average person with an average lifestyle needs 2,000 of them per day.

Royal Marine recruits get 4 meals a day so that they can consume the necessary 4,500 calories.

I have found a wide variety of ranges of power output as displayed by exercise machines, but 100 W seems reasonably achievable. So if you manage this for 30 min, you expend 100 x 30 x 60 = 180 kJ = 45 kCal so it is much easier to lose weight by eating less than running more.

If you over eat, you don't keep expanding indefinitely because it takes energy to keep those bigger fat cells alive and to move them around. If you want to lose weight and can bare to get down to 1,000 Cal/day, you should lose 1 kg per week.

[duncan webster 1Participant @duncanwebster1]

Posted by Michael Gilligan on 13/07/2023 08:16:24:

As an aside … my Human Biology professor assured us that [aside from issues relating to roughage and allergies] a diet of Eggs and Guinness would sustain the human body quite effectively.

MichaelG.

Friend of mine at university managed a whole year on a diet of ham sandwiches and best bitter. Unfortunately the bitter/butty ratio increased as the year went on, and he didn't re-appear after the end of year exams.

[HOWARDTParticipant @howardt]

There was a news article somewhere this week about an American man who was overweight and had tried different diets to no avail. So he decided he wouldn’t give anything up in his diet but instead only eat when he was hungry. He didnt say how much he ate each time but he lost over 100lbs over two years and kept it off. So perhaps rather than count calories or exercise we should all only eat as necessary, difficult I know if you live with someone.

[Robin GrahamParticipant @robingraham42208]

Posted by Cabinet Enforcer on 13/07/2023 01:33:55:

Fourth link on my google search, your google-fu is weak Robin-san.

**LINK**

Edited By Cabinet Enforcer on 13/07/2023 01:34:20

Edited By Cabinet Enforcer on 13/07/2023 01:34:38

Thanks – my Google-fu is indeed failing it seems. If only they called them Atwater calories I'd have got there! I did know about the factor of 1000 between nutritional and 'physics' calories though. Anyhow, you have answered my question.

The question arose from idle pondering rather than any personal dietary concerns, but reading other responses I do wonder how useful these measures are. I suppose it's just a matter of averages and perhaps extremes. Personally my weight has been pretty stable over the last 50 years without any need to diet or feed up – I just eat what I want when I want. Doesn't work for everyone obviously – metabolism is complicated!

Robin.

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