How Much ATP Does a Human Body Produce Every Day?

Today I learned that the human body makes its weight in ATP (a key component of the Krebs cycle") every day. When I read this I wondered if it could possibly be true. Here's what Grok had to say:

My Query to Grok: Is it true that we make our body weight worth of ATP every day?

Yes, it's true. The human body turns over (produces and consumes) an amount of ATP roughly equivalent to its own body weight each day, though the exact figure varies by activity level and individual.

At any given moment, the body contains only about 250 grams of ATP (plus some ADP). However, ATP is rapidly recycled: it's hydrolyzed to ADP + phosphate to release energy, then resynthesized using energy from food. This cycle happens thousands of times per day per molecule.

Reliable sources estimate daily ATP turnover as:

    • 50–75 kg for an average adult (often cited as ~100–150 moles of ATP hydrolyzed and regenerated daily).
    • Around 50 kg in sources like Wikipedia.
    • ~60 kg in BioNumbers database.
    • Up to 100 kg or more during high activity in some physiology texts.

For a typical 70 kg person, this is approximately one body weight's worth per day at rest or moderate activity. During intense exercise, the rate can increase dramatically (e.g., up to 0.5–1 kg per minute). The key point is the enormous flux: even though net ATP storage is tiny—your cells are constantly churning through it to power everything from muscle contraction to brain function.

This fact is widely accepted in biochemistry and physiology textbooks and is often used to illustrate how dynamic cellular energy metabolism is.

Tutorial on the Krebs Cycle (Also from Grok):

The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle, is a central metabolic pathway in cellular respiration that occurs within the mitochondria of eukaryotic cells, efficiently converting nutrients from carbohydrates, fats, and proteins into usable energy. It begins when acetyl-CoA—derived primarily from the breakdown of glucose via glycolysis—combines with oxaloacetate to form citrate, initiating a series of eight enzymatic reactions that systematically oxidize the molecule, releasing carbon dioxide as a byproduct (which we exhale) and generating high-energy electron carriers like NADH and FADH2, along with a small amount of ATP directly through substrate-level phosphorylation. These electron carriers then feed into the electron transport chain to produce the bulk of the cell's ATP via oxidative phosphorylation, yielding up to 38 ATP molecules per glucose molecule overall. The cycle is highly efficient, regenerating oxaloacetate to allow continuous operation, and it's tightly regulated by factors like ATP levels and enzyme inhibitors to match the cell's energy demands, playing a crucial role not only in energy production but also in providing intermediates for biosynthesis of amino acids, nucleotides, and other essential compounds.
 

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Quotes for Today

In the past, I've posted some of the most interesting quotes I've encountered. I haven't done that for awhile, but today seems like a good day for another batch of quotes from my collection. Here they are:

“If I were rich, I would have a plaque made up, and sent to every judge in America, bearing a statement made by Adam Smith more than two and a half centuries ago: ‘Mercy to the guilty is cruelty to the innocent.’” — Thomas Sowell

The urge to save humanity is almost always only a false-face for the urge to rule it." - H.L. Mencken

“In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.” - Galileo

"Laws are spider webs through which the big flies pass and the little ones get caught." -Balzac

"You are not a traveler on this path, you are the path itself, unfolding with every step." ~ Rumi

“The secret of getting ahead is getting started.” — Mark Twain

“We should not write so that it is possible for the reader to understand us, but so that it is impossible for him to misunderstand us.” ― Quintilian

"The moment we no longer have a free press, anything can happen. What makes it possible for a totalitarian or any other dictatorship to rule is that people are not informed; how can you have an opinion if you are not informed? If everybody always lies to you, the consequence is not that you believe the lies, but rather that nobody believes anything any longer. This is because lies, by their very nature, have to be changed, and a lying government has constantly to rewrite its own history. On the receiving end you get not only one lie—a lie which you could go on for the rest of your days—but you get a great number of lies, depending on how the political wind blows. And a people that no longer can believe anything cannot make up its mind. It is deprived not only of its capacity to act but also of its capacity to think and to judge. And with such a people you can then do what you please." - Hannah Arendt

“The obedient always think of themselves as virtuous rather than cowardly.” ― George Carlin

“Under peaceful conditions, the warlike man attacks himself.” ― Friedrich Nietzsche

"I look upon indolence as a sort of suicide; for the man is effectually destroyed, though the appetites of the brute may survive." Lord Chesterfield

“Do not interfere with an enemy that is in the process of destroying itself.” -Sun Tzu

“Even the written instructions which Winston received, and which he invariably got rid of as soon as he had dealt with them, never stated or implied that an act of forgery was to be committed: always the reference was to slips, errors, misprints, or misquotations which it was necessary to put right in the interests of accuracy.” - George Orwell, 1984

“I find it truly surreal to read academics denying the existence of intelligence. Academics are obsessed with intelligence. They discuss it endlessly in considering student admissions, in hiring faculty and staff, and especially in their gossip about one another. Nor can citizens or policymakers ignore the concept, regardless of their politics. People who say that IQ is meaningless will quickly invoke it when the discussion turns to executing a murderer with an IQ of 64 [or] removing lead paint that lowers a child’s IQ by five points.” - Steven Pinker

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Words Are Not Violence

When I was growing up, we often said "Sticks and stones will break my bones, but words will never hurt me." Last year, I spoke these words at a free speech presentation at a local library and the participants glared at me. I get the same stares when, after I am told that something I said was offensive, I respond by saying "You do you." or "Live and let live" or "To each his own." There are other expressions that don't fare well around the many self-appointed nannies inhabiting American universities, where wokeness still runs amok:

Be yourself

Do your thing

Do your own thing

Be true to yourself

To each their own

Live and let live

I was reminded that it still takes thick skin to say these common sense sorts of things in many places when I spotted this meme:

Words are not violence, yet this obvious and useful distinction is being willfully ignored and at great peril to societal flourishing. In his article at Free Press, "Bury the ‘Words Are Violence’ Cliché," Greg Lukianoff comments on this important distinction:

Words are not bullets. Words can’t strike a man from 142 yards away, causing a torrent of blood to erupt from his wound, sending him first to the hospital and then to the morgue. Only bullets can do that.

Upholding that distinction is the North Star of everything I do as president of the Foundation for Individual Rights and Expression (FIRE). For years, I’ve warned that equating words with violence erases the bright line liberal societies drew after centuries of bloodshed. The law draws this line with precision. Advocacy, even vile advocacy, remains protected unless it is intended and likely to produce imminent lawless action. That’s the Brandenburg standard, and it exists because the alternative is to let the powerful decide which ideas are allowed.

Or, as the Supreme Court put it in Texas v. Johnson, “If there is a bedrock principle underlying the First Amendment, it is that the government may not prohibit the expression of an idea simply because society finds the idea itself offensive or disagreeable.” These aren’t lawyerly niceties; they are the safety valves of pluralism. Blur them, and real violence becomes more, not less, likely.

Campus culture has been eroding that line for years. Students are told that offensive ideas are “harm,” that “silence is violence,” and—in a flourish that should now embarrass its users—that speech can be “literally” violence. Jonathan Haidt and I pushed back on that argument almost a decade ago. It’s conceptually wrong and practically dangerous—and has only grown in influence. Teach students that objectionable speech is violence and you invite them to see their own aggression as self-defense. [emphasis added]. This is the bloody fallacy we just witnessed: Accept the premise that rhetoric is a physical attack and you hand extremists a moral permission slip to answer speech with force. We need to bury this trope. Retire it—from classrooms, HR trainings, and editorials—for good.

The numbers show how far the rot has spread. FIRE’s new College Free Speech Rankings, which surveyed nearly 70,000 students across 257 campuses, find a record share now rationalizing coercion. Roughly 34 percent of students say that using violence to stop a campus speech can be acceptable in some circumstances; roughly 70–72 percent say the same about shouting down speakers. In 2021, the violence number was in the low 20s; by last year it was 32 percent. It should be zero. A university that can’t persuade students to reject violence categorically is failing at the first task of liberal education.

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The citizens of large countries are rapidly disappearing.

Stunning numbers. The citizens of large countries are rapidly disappearing and it's not because of a war or a plague.. It is an unprecedented loss in population:

South Korea is quietly living through something no society has ever survived: a 96% population collapse in just four generations — with zero war, zero plague, zero famine. 100 people today → 25 children → 6 grandchildren → 4 great-grandchildren. That’s it. Game over for an entire nation by ~2125 if fertility stays where it is (0.68–0.72). . . . Japan, Taiwan, Italy, Spain, Singapore, Hong Kong, Poland, Greece — all following the same curve, just 10–20 years behind.

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