Sciencey Question about Calories

ScreeField wrote: »

Sciencey Answer:

“Calories” are a measurement of energy — it’s just a unit of energy, like Watts or Joules. Or even like: gallons or cups or teaspoons. It's just a unit of measurement. In this case, energy.

Generally, determining how many calories are in food is done by burning the food and calculating the released heat in something called a Bomb Calorimeter. Think of using a hamburger instead of charcoal in your barbecue and calculating how many hamburgers it takes to heat up a cup of water.

1 Calorie = energy it takes to heat up 1 liter (kg) of water by 1 degree Celsius

The math:

Q = mcp^T
= (1kg)(4.18 J/g*C)(1C)
= 4.18 kilojoules
= 1 calorie

So, calories are just energy. However, what your body does with that energy is a whole different story. We started with physics and now we have to shift into chemistry.

When you eat a molecule of sucrose (sugar) what your body does first to it is to break all of the sucrose molecule’s bonds to release energy, but breaking molecular bonds takes energy.

Sucrose has lots of bonds:

C-C bonds: 10
O-H bonds: 8
C-H bonds: 14
C-O bonds: 14

Each of these bonds has different energies:

C-C = 346 kJ/mol
C-H = 411 kJ/mol
O-H = 459 kJ/mol
C-O = 358 kJ/mol

So, you simply add up the bonds and sum the energy per bond.

C-C = 346 kJ/mol x 10 bonds = 3,460 kJ/mol
C-H = 411 kJ/mol x 14 bonds = 5,754 kJ/mol
O-H = 459 kJ/mol x 8 bonds = 3,672 kJ/mol
C-O = 358 kJ/mol x 14 bonds = 5,012 kJ/mol

Total energy it takes to break apart a sucrose molecule is the sum of the above: 17,898 kJ/mol

The next step is to reform those broken bonds into carbon dioxide and water. This also takes energy. And, you have to apply the Principle of Stoichiometric Balance which means, when you are transforming one thing to another with a chemical reaction, you can't destroy its fundamental atoms. You have to end up with the same number of each atom.

The sucrose molecule looks like this:

C12 H22 C11

After digestion, there must be 12 carbons in the final product(s). They can’t go anywhere else. So, to convert the above to carbon dioxide and oxygen, you have to add 12 oxygen molecules to balance both sides of the equation:

C12 H22 O11 + 12O2 = 12CO2 + 11H2O


Then, there’s also the released energy to account for. There are a number of charts online that map metabolic pathways. There are maps for glucose alone that could be printed in 10 pt font and take up entire walls. One of the more well known maps was created by Dr. Donald Nicholson and I believe his map is online. None of the metabolic pathways charts are complete. They are all still works in progress.

If you have access to a glucose metabolic pathway chart, you can see the many many different processes just to use up a glucose molecule — and you can see why there are differences in metabolism of different foods into calories. A calorie is always a calorie (that’s like saying a gallon is always a gallon). However, its the: 1) energy availability of different foods and 2) metabolic processes cause a large variation in results.

initialsdeebee wrote: »

I'm curious about the rate at which we can assimilate/store calories as weight.

onyxgirl17 wrote: »

ScreeField wrote: »

Sciencey Answer:

“Calories” are a measurement of energy — it’s just a unit of energy, like Watts or Joules. Or even like: gallons or cups or teaspoons. It's just a unit of measurement. In this case, energy.

Generally, determining how many calories are in food is done by burning the food and calculating the released heat in something called a Bomb Calorimeter. Think of using a hamburger instead of charcoal in your barbecue and calculating how many hamburgers it takes to heat up a cup of water.

1 Calorie = energy it takes to heat up 1 liter (kg) of water by 1 degree Celsius

The math:

Q = mcp^T
= (1kg)(4.18 J/g*C)(1C)
= 4.18 kilojoules
= 1 calorie

So, calories are just energy. However, what your body does with that energy is a whole different story. We started with physics and now we have to shift into chemistry.

When you eat a molecule of sucrose (sugar) what your body does first to it is to break all of the sucrose molecule’s bonds to release energy, but breaking molecular bonds takes energy.

Sucrose has lots of bonds:

C-C bonds: 10
O-H bonds: 8
C-H bonds: 14
C-O bonds: 14

Each of these bonds has different energies:

C-C = 346 kJ/mol
C-H = 411 kJ/mol
O-H = 459 kJ/mol
C-O = 358 kJ/mol

So, you simply add up the bonds and sum the energy per bond.

C-C = 346 kJ/mol x 10 bonds = 3,460 kJ/mol
C-H = 411 kJ/mol x 14 bonds = 5,754 kJ/mol
O-H = 459 kJ/mol x 8 bonds = 3,672 kJ/mol
C-O = 358 kJ/mol x 14 bonds = 5,012 kJ/mol

Total energy it takes to break apart a sucrose molecule is the sum of the above: 17,898 kJ/mol

The next step is to reform those broken bonds into carbon dioxide and water. This also takes energy. And, you have to apply the Principle of Stoichiometric Balance which means, when you are transforming one thing to another with a chemical reaction, you can't destroy its fundamental atoms. You have to end up with the same number of each atom.

The sucrose molecule looks like this:

C12 H22 C11

After digestion, there must be 12 carbons in the final product(s). They can’t go anywhere else. So, to convert the above to carbon dioxide and oxygen, you have to add 12 oxygen molecules to balance both sides of the equation:

C12 H22 O11 + 12O2 = 12CO2 + 11H2O


Then, there’s also the released energy to account for. There are a number of charts online that map metabolic pathways. There are maps for glucose alone that could be printed in 10 pt font and take up entire walls. One of the more well known maps was created by Dr. Donald Nicholson and I believe his map is online. None of the metabolic pathways charts are complete. They are all still works in progress.

If you have access to a glucose metabolic pathway chart, you can see the many many different processes just to use up a glucose molecule — and you can see why there are differences in metabolism of different foods into calories. A calorie is always a calorie (that’s like saying a gallon is always a gallon). However, its the: 1) energy availability of different foods and 2) metabolic processes cause a large variation in results.

I like a lot of what you have pointed out here however...17898 kJ is the estimate for an entire mole of sucrose molecules. The amount of energy released by ONE molecule is that number divided by 6.02 x 10^23 molecules per mole. Significantly less for each molecule.

Also... breaking bonds requires energy while reforming bonds actually releases energy, it's called the energy payoff. In order to find the enthalpy, bonds broken - bonds formed is the general equation when using bond energies for your calculation.

senecarr wrote: »

professionalHobbyist wrote: »

martinecoates wrote: »

senecarr wrote: »

nvsmomketo wrote: »

Yeah, it is roughly 7000 exra kcal to gain 2 lobs. Roughly. And that is extra, so not including what your body burns in a day.

I think it would also depend on what your body can physically do. I amguessing that there is a point where your body gives up on absorbing and just passes the food through. Just guessing.

Plus some foods are more easiliy absorbed than others. That would make a difference.

Serum insulin levels will also affect how fast you put on fat. Insulin helps store fat, so if your insulin levels are higher, you may store fat more efficinetly. Carbohydrates will raise insulin, as will protein to a much lesser degree. Those with insulin resistance (T2D or prediabetes) will have higher levels of insulin in their blood stream too.

Insulin tells cells to store fat. That means the fat already has to be there, available to the cells. That means, the fat already has to be in your body.
It's a common misconception that people get about insulin. Honestly, that your body stores it is actually a good thing - the alternative is that your blood stream has fat floating around which we tent to call cholesterol and triglycerides and associate with negative health outcomes.
In people who already are generally considered healthy and have a low body fat, you'll find their insulin is more active and stores fat faster. Insulin resistance is the body doing this slower and less.
None of that really has to do with fats being taken up from food.

actually insulin signals cells to take up glucose not fat, what you posted is completely and utterly wrong! The glucose can be then used for energy or stored and eventually can be converted to fat. keeping it simple gotta go to work.

^^^This is true

This thread is full of utter disinformation

Your mitochondria burns your fat. Eat a deficit and exercise.

As your muscles seek fuel your mitochondria sources glycogen and lipid mix. Exercise in a fasted state and your mitochondria physically adapts over time to source more fat

I have lost 145 lbs of fat and reversed my diabetes doing this with dr and nutritionist supervison and 6 month blood tests along the way

Calorie deficit sets the stage. What you do with it is a personal decision. I'm enjoying endurance training in that state.

It works for me.

But please anyone in this thread look up some of this stuff in Google

There is so much wrong in this thread it is scary.

I've already clarified why martinecoates was over simplifying.
Go take a look at what I posted. Using Google isn't simply typing in what you want to hear.
There is nothing special about fasted exercise. Absolutely nothing. For all the increased fat burning you're doing while fasted, your body will just source more energy from carbohydrates later if you eat foods that are a mix. The human body isn't that naive. It's had to become highly adapt at using any and all fuel it comes across, or we wouldn't be here today.