When somebody loses weight, where does the fat go?


(Bunny) #1

This research article was featured on a recent episode of Ben Greenfield‘s podcast and thought it was of interest to ketonauts:

When somebody loses weight, where does the fat go?

-How fat actually gets burnt…6:20 - Ben Greenfield

  • Law of conservation of mass: Mass, in an isolated system, is neither created nor destroyed by chemical reactions or physical transformations
  • Fat is primarily disposed of via the breath
  • Calories, as well as excess carbs and proteins, are converted into triglycerides and stored in lipid droplets of adipocytes
  • Excess dietary fat undergoes lipolysis, and then reesterification
  • Triglycerides are composed of carbon, hydrogen, and oxygen
  • Oxidation: requires inhalation of oxygen
  • Study: When someone loses weight, where does the fat go?
  • For 22 pounds of fat to be oxidized, 64 pounds of oxygen must be inhaled
  • Results in 61 pounds of carbon dioxide excreted via the lungs and 24 pounds of water excreted via urine, sweat, feces, and breath
  • Average of 17,000 breaths per day will excrete .32 lbs of carbon
  • Sources of carbon (other than eating coal) are: dietary carbs, proteins, and fats
  • If you didn’t get all that, get this: Losing fat means consuming less carbon than you’ve exhaled. Even small quantities of food can foil your efforts at weight loss. The simple solution is to move more and eat less. …More


Richard Morris Metabolic Testing at Ketofest Down Under 2018

The mathematics of weight loss | Ruben Meerman | TEDxQUT (edited version)

(Alec) #2

Quote from Mr Greenfield above: “The simple solution is to move more and eat less”


(Bunny) #3


“…Fitness Expert Jillian Michaels Shares Weight Loss … “To burn that off, you have to eat less food and move more.”. …More

(Hyperbole- it’s the best thing in the universe! ) #4

Dietitians are redeemed! They are the only one’s who got it right! Not many of them, but still.

(Alec) #5

Hard words to read… :joy::joy::joy:

(Jane) #6

Yep. And the human body is an isolated system. :laughing:

(Jane) #7

Yep Julian Michaels makes a living promoting that - follow the money trail!!! :laughing:

(John) #8

I had read the underlying research article before. Made perfect sense. That is why it seems like you are peeing off your weight, because of the water loss portion, which we can detect.

We rarely think about how much the oxygen we absorb from each breath weighs, or how much the carbon dioxide we exhale weighs, and how that one little carbon atom in every CO2 molecule we breathe out is where most of the weight goes.

That carbon is the soot from the biological fire as we oxidize the hydrocarbons from digested food to generate energy to fuel our body processes and movement.

And in fact, if we are breathing, we are losing weight at a pretty steady rate every day - about 0.5 to 0.7 pounds depending on metabolic rate. All we can do is manage how much of that we replace by eating.

One interesting takeaway was that physical activity increases metabolic rate while you are doing it, causing you to breathe a bit more often, which means more carbon is exhaled, compared to doing nothing. But the increase is not huge, and running for a full hour would equate to about an extra 47g of carbon+water loss per day, or about one-tenth of a pound.

So yes, I do believe if you move more without eating more, you lose a little more weight. But food intake is a much bigger lever, so it doesn’t take a lot of additional food to replace the extra carbon exhaled from increased activity.

(Ethan) #9

The sheer fact that we KNOW that moving more and eating less isn’t the solution means Ben Greenfield got some key details wrong in the cause->effect analysis

(Jane Ellis) #10

Interesting, I watched 1 season of biggest loser and decided I could not stand Jillian and I never watched it again! :rofl:

(Bunny) #11

I am assuming “moving more” is more about breathing as each human breath contains 33 mg. CO2 with 8.9 mg comprised of carbon output.

Each calorie: carbohydrates (sugar; is almost like charcoal), fat and protein contains 2 carbon atoms or may even contain up to 4 for output?[5][6]

Hard for some to swallow but the human body can be in several different states simultaneously or more of one and not enough of the other; chemical, mechanical or thermal but notice it says “Majority?” It does not say ‘all of the weight loss occurs this way’ ???

Majority of weight loss occurs 'via breathing’

"None of this biochemistry is new," say the authors, "but for unknown reasons it seems nobody has thought of performing these calculations before. The quantities make perfect sense but we were surprised by the numbers that popped out."

The results suggest that the lungs are the main excretory organ for weight loss, with the H20 produced by oxidation departing the body in urine, feces, breath and other bodily fluids.

On average, a person weighing 70 kg will exhale around 200 ml of CO2 in 12 breaths each minute. The authors calculate that each breath contains 33 mg of CO2, with 8.9 mg comprised of carbon. A total of 17,280 breaths during the day will get rid of at least 200 g of carbon, with roughly a third of this weight loss occurring during 8 hours of sleep.

The carbon that is lost through exhalation is only replaced through the consumption of food and beverages such as fruit juice, milk and soft drinks. “Keeping the weight off simply requires that you put less back in by eating than you’ve exhaled by breathing,” state the authors.

”…Eat less, move more…”

The amount of carbon that is lost can be increased with exercise. By substituting 1 hour of rest for 1 hour of moderate exercise such as jogging, the metabolic rate is increased sevenfold, removing an additional 40 g of carbon from the body, increasing the daily total by around 20% to 240 g.

However, this can easily be offset with unhealthy eating. A single 100 g muffin, for example, provides around 20% of an average person’s total daily energy requirement. “Physical activity as a weight loss strategy is, therefore, easily foiled by relatively small quantities of excess food,” write the authors. The solution is a traditional one - “eat less, move more.” …More


[1] Your Sugar Might Be Made With Animal Bones. Sorry, Vegans. …And here’s the bone-chilling truth…

[2] Make charcoal (carbon) by the dehydration of sugar

[3] “…concentrated sulfuric acid, granulated table sugar performs a degradation reaction which changes its form to a black solid-liquid mixture…” …More

[4] Black Fire Snake - Amazing Science Experiment

[5] FATS: They may contain as few as 4 carbon atoms or as many as 24. Because fatty acids are synthesized from fragments containing two carbon atoms, the number of carbon atoms in the chain is almost always an even number. …More


[6] “…Carbon is the primary component of macromolecules, including proteins, lipids, nucleic acids, and carbohydrates. …” …More

(Brian) #12

“When somebody loses weight, where does the fat go?”

I’m perfectly happy to answer that question with a one word answer: “Away!”

:wink: :smiley:

(Jane Ellis) #13


(John) #14

New weight loss technique! Exhale twice as often as you inhale!

(Bunny) #15

Or hopping :kangaroo: more? …lol

The Hopping Roos of Australia Solve World Obesity Epidemic!


(Alec) #16

Now that’s not a headline I thought I would ever read. :joy::joy::joy:


YES. Inhale less, exhale more! :hot_face:

Seriously though, how many ways are there to restate the second law of thermodynamic theory of weight loss? It still avoids the basic question of the availability of fat as a substrate. If fat is not available due to high insulin levels how is it ever going to be exhaled?

I like to think of it as a gas/electric hybrid vehicle…
What’s supposed to happen is the battery powers the car until it reaches a low state of charge, or the power requirement to move the vehicle overwhelms the battery’s capacity to discharge at the rate required. Then the engine kicks in to recharge the battery. Now what if there’s a defect where the battery gets charged but there’s a blown fuse in the circuit to power the car? The engine will run all the time to power the car and keep trying to charge the battery even though it is already full.

Battery = fat
Engine = food
Defect = high insulin

(Scott) #18

In thinking about this exhaling fat I suppose this is why I need to clean the inside of the windshield from time to time. Also thank God the burning of fat doesn’t result in black ash. I would hate to see the the result of that.

(Jane Ellis) #19

I’ve always wondered where all that stuff on the windshield came from!

(Scott) #20

That would be the 10 year old Krispy Kreme doughnut!