Dear Science

Can I Photosynthesize Seltzer Water Into Fat?

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Dear Science,

I have switched to flavored carbonated water to reduce my calorie intake, but I have a question: What happens to the carbon in carbonated water? In photosynthesis, CO2 is converted into sugar and free oxygen, right? Since I don't expel a bunch of gas, I wonder what happens to the CO2 once it's inside of me. I suspect the carbon and oxygen are coming apart inside. Does the human body have some mechanism to turn this CO2 into sugar and oxygen, just like in plants? And would that in turn create an even larger me? Is "zero calories" a misnomer? Can the gas be turned into products that are the building blocks of our bodies without ever needing to have calories used or released?

I'm just wondering because my switch from beer to sparkling water has had no net effect on my physique.

Water Ballooned

Your question is making Science pretty damn sad. Really sad. For your curiosity, you are commended. For your attempt to think through a question? Only praise! Science just wishes your high school (hell, middle school) science class did a better job instructing you.

The carbon in carbonated water is carbon dioxide (CO2). When you drink carbonated water, it remains CO2 and you breathe it out as CO2—not just as burps, but also as breath. At no point in this process is the carbon split from the oxygen and turned into sugar—only plants can do that. And you're not a plant! So, good news: Switching from beer to carbonated drinks (without sweeteners) is a reasonable way to try to lose weight. The CO2 in such a carbonated drink is truly calorie free.

Plants split up CO2 into hydrogen and carbon chains (sugars, basically) plus oxygen by capturing sunlight and stuffing high-energy electrons onto the carbon in the carbon dioxide, ripping apart water for the hydrogen, and releasing oxygen as a waste product. Animals, including humans, can do none of this photosynthesis.

Photosynthesis was discovered in halting steps, starting all the way back in the 1600s. The chain of thought started by scientists noticing that plants grew and gained weight without really changing the weight of the soil they're grown in. In other words, the plant had to grow not by consuming the soil, but by remaking water and the air around it. Later experiments revolved around how an animal (like a mouse) would perish shortly after being placed in a closed glass container, yet if a plant was placed in the glass container, the mouse would live.

Humans can't photosynthesize because we lack chloroplasts—the parts of the plant that perform this splendid trick. Just like the mouse in the jar could not break down the carbon dioxide surrounding it for oxygen and energy, you can't convert your seltzer water into food and air.

Wearily yours,


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Comments (9) RSS

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I really like the respectful, non-patronizing manner in which Jonathan responded to the reader's question.

Jonathan - when people are asking for your expertise, telling them that they lack a middle school knowledge level of science might not be the least offensive way of pointing out someone's ignorance. I'm not saying that the question writer was offended - but I would hardly blame him/her if he/she was.

Also, unless the writer was a 5 year old, I would doubt that your "good for you for thinking about it" comment really came across as respectful.
Posted by MuDPhuD on December 7, 2011 at 12:24 PM · Report this
Eh. Given that most adults could not pass a middle school science test without a refresher, there's no shame in not remembering the details of some of this stuff. I don't think the problem is that schools aren't educating us. Most of us don't retain information that we don't need or use on a regular basis. However, schools should teach us how to think and how the process of science works. The poster thought that perhaps s/he had, in thirty seconds, had an original thought that might turn conventional wisdom on its head. If for no other reason than that, s/he deserves a gentle reprimand. Science is sufficiently advanced that none of us non-specialists are going to have a casual breakthrough thought while sipping a diet soda. We should all know better than that.
Posted by strange observer on December 8, 2011 at 7:57 AM · Report this
Fenrox 3
I would rather read a pithy article where he talks down to me than his normal fare.
Posted by Fenrox on December 8, 2011 at 9:44 AM · Report this
Well that begs the question - will my plants gain weight if I feed them flavored seltzer? More than they would from an equivalent by weight amount of regular water? Is it a kind of fertilizer? Answers, science, I need answers!
Posted by gnot on December 9, 2011 at 1:32 PM · Report this
Not understanding that humans don't photosynthesize is pretty boneheaded. I don't think Jonathan was condescending to point out that this is middle school level science. I agree with him that it is a sad, sad commentary on the lack of super basic knowledge people can have after graduating high school.
Posted by non-science person with at least half a brain on December 11, 2011 at 3:13 PM · Report this
Pretty mind-blowing that this was even a question, to be honest. Dear Science handled it relatively well in light of that.
Posted by jesus fucking christ on December 11, 2011 at 4:03 PM · Report this
Sandiai 7
@4 I know your question may be tongue-in-cheek somewhat, but my plants love carbonated water. I don't know about the sweetener though.

I too was saddened by the question. I went to a public school in Wisconsin in the 80's, and we had a year of required Biology, and 2 years of optional biology, which everyone took (because it was fun and the other choices were boring). We covered all the basics in that first year that would have answered this question, including the laws of thermodynamics one would have to break in order to make sugars from CO2 without USING energy.
Do the curricula of public schools not require biology nowadays?
Posted by Sandiai on December 12, 2011 at 4:21 PM · Report this
Any way we can roast Congress on a stick?
That's already 100% pure fat and putrid gristle.
Posted by auntie grizelda on December 13, 2011 at 6:06 PM · Report this
@ 5 and @7 - I think that we are making an assumption about the education of the original poster. How do we know that he/she has even graduated high school? Not everyone has, in fact around 15% have not. Seems a little condescending of Jonathan to berate someones education without knowing whether or not they were educated.

@6 - the way that Jonathan should have handled it is not post the question at all. I doubt that the majority of readers learned anything of scientific value from the article. Jonathan used the question to give himself the chance to call someone stupid.
Posted by MuDPhuD on December 14, 2011 at 7:47 AM · Report this

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