Tag Archives: carbohydrates

How Energy Is Obtained From Carbohydrates In Food

5 Feb

As promised, here is my explanation of what exactly it is that turns all the carbohydrates we eat into energy. I know it’s not exactly relevant, but it is so important in the name of food sciences and nutrition. I’m not claiming to be an expert here, just a student with a biochemistry class under my belt (and a professor that fostered an undying love and appreciation for biochemistry and the mechanics of life and metabolism). In other words, I’m a nerd. And that’s ok. I’ll try not to get too wordy- my goal is to present this material in a way that someone with a basic high school science background can understand. If you have absolutely no science background… you might struggle.

Before I jump in, I’d also like to note that carbohydrates are not the only source of energy we get from food. Fats can be broken down into fatty acids and glycerol, and proteins into amino acids, all of which by one process or another, end up in the Krebs Cycle and get turned into energy. I’m going to focus on carbohydrates because it is what my previous post was about. Maybe I’ll do a post on the others another time- fatty acids actually produce more energy per molecule than glucose!

Basically, the energy that I refer to in our body is actually ATP. That’s Adenosine Triphosphate. This molecule has a carbon backbone, but the important part is the phosphate groups. Attached to the carbon backbone are 3 phosphates, connected to each other by oxygens. There are also oxygens on the sides of the phosphate molecules. Each of these oxygens have a negative charge, and as Paula Abdul so wisely said- opposites attract. By this logic, all the negative charges repel each other. All these negatively charged oxygens trying to get away form each other creates a large amount of potential energy. If you remove even one of the phosphate groups, the molecule is much happier, and this conversion from ATP to ADP (adenosine diphosphate) is a crucial source of energy for powering life processes.

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So, when food is digested, if it’s going to end up as energy,the end goal is to convert it to ATP.

In food contexts, a “carbohydrate” is used to refer to a food that is rich in complex carbohydrates/sugars (cereal, bread, pasta) or simple carbohydrates/sugars (candy, jams, desserts). A complex carbohydrate is also known as a complex sugar, and a simple carbohydrate is known as a simple sugar (or what we commonly just call sugar). All this terminology gets a bit confusing because we tend to use names that have many overlapping meanings, and most people have no idea what each actually means, or what the difference is.

When carbohydrates are digested by the body, they will be broken down into their smallest form, which is glucose. Glucose is a simple sugar with the formula C6H12O6 and is very, very, very important in metabolic systems- Life would not occur without glucose! The only carbohydrates that aren’t broken down into glucose are those made up of dietary fibers, which cannot be digested.

Once you have glucose, there are a series of processes that occur to yield ATP. These are:

  1. Glycolysis
  2. Respiration
  3. Krebs Cycle
  4. Electron Transport Chain

Ok, let’s look at these.

GLYCOLYSIS: literally means break down of glycogen, this is the process by which glucose is broken down from a 6 carbon molecule into a 3 carbon molecule.

I wrote out my explanations, because I find using images so much easier to get my point across, and I didn't want to spend hours on google searching for the right one!

I wrote out my explanations, because I find using images so much easier to get my point across, and I didn’t want to spend hours on google searching for the right one!

RESPIRATION: process by which pyruvate is converted to acetyl-coA

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KREBS CYCLE: main source of energy production- a series reactions producing ATP and other waste products

20130205-011925.jpg 20130205-012017.jpg

ELECTRON TRANSPORT CHAIN: consists of a series of special electron carrier proteins that channel electrons from NADH to terminal electron acceptors such as oxygen. At the end of the chain, a pair of electrons are transferred to oxygen and water is formed, and the enzyme ATP synthase takes the energy of the protons to synthesize ATP.

electron-transport-chain-cpg-notes

TOTAL ENERGY YIELD

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…And this is all from ONE glucose molecule.

So, I hope that clears it up a little bit. Obviously, it is much more complicated than this, but at least now you have a brief overview of the process by which carbohydrates are turned into energy!

Let me know if there’s anything I can clear up for you.

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Pre-Stamina Day Carbo-Loading

5 Feb

Today, I may well go through hell on earth. As I’ve mentioned- I have 90 minutes of dance, break, then 2 and half hours more of dance. Add in the fact that I have a 3 mile walk in between and no ride next week, and that sounds bad enough. But oh, it gets worse. Several of us are competing in a little over a month, so our teacher has decided to work on our stamina until then. Our other teacher (the stricter and “I don’t care if you’re so exhausted that you’re about to pass out keep doing it perfectly” teacher) is coming back and our current teacher has warned us that tuesday will be a stamina day. If my powers of prediction are correct, I’m gonna go ahead and guess that every class in february will be stamina day. Shoot me.

The point of saying all of this is to a) warn you this may be my last post as I anticipate not being alive tomorrow and b) the more pertinent option, explain to you why I carbo loaded this weekend

In order to get through stamina day, I’m going to need all the energy I can get. To read more about how your body reaps energy from carbohydrates, click here! (I LOVE biochemistry and I had way too much on the subject to put it in this post). But my point is, carbohydrates (and lots of them) are not only great but necessary before a show or competition, or even a long rehearsal.

I was going to write out an eating game centered around a TV show (read: Doctor Who) – a manifestation of a drinking game but the goal being carbo-loading instead of getting wasted. Not as fun, but a more productive use of the hours I’m spending watching Doctor Who. The only problem is I got to the end of season 2 (of the newer series that began in 2005), where SPOILER ALERT Rose and the Doctor say goodbye and confess their love (or almost) and whatnot and I literally started bawling. I can’t even. I love Rose Tyler more than words can describe. I thought losing Christopher Eccleston was bad, but losing Billie Piper, and tearing apart Rose and the Doctor- man that broke me. I am actually so glad my flatmate went out tonight because she’d think I’m mental. All hysterical over a TV program. Either way, any plans of doing anything productive while watching that show have been derailed as I try and come to terms with the end of the era of Rose. Plus, right now the game would look something like “Eat a sandwich every time you cry”… and I would run out of bread.

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For the full heart breaking effect, click on it!

So- new plan! I’m going to present some of the best foods to eat while carbo-loading. But be warned- consumption of all of these in a short amount of time (what I’m doing) should only be done in the face of serious energy expenditure. Not your average workout. Just remember, if you’re eating it, you have to do enough exercise to work it off. (And likewise, you need to eat enough to fuel your work out, so plan accordingly).

1. Rice! Rice is great. It should be a staple in EVERYONE’S diet. I mean honestly what’s not to like. It has 45 g of carbohydrates per serving- 0 of which are from sugar, 205 calories- 4 of which are from fat, 0 g of fat- saturated and trans. Best part- it’s composition is 90% carbohydrate. Take a look at this make up:

Screen shot 2013-02-04 at 10.19.20 PM

I mean it just doesn’t get better than that. All of the data I gave above was for 1 serving, but if you know me and my inability  to determine serving size, I ended up eating about 3-4 servings of rice over the weekend. Still not as much rice as I ate when I went to China for 3 weeks in the summer- literally it was all I ate when we went out to eat. Me being the fussy eater I am barely ate anything of the main meals (I’m sorry but I REFUSE to eat crunchy chicken, when by crunchy they mean talons and heads), so my god, when that rice dish came out at the end, I enjoyed it.

2. Pasta. Pasta has the ability to get quite fatty quite quickly if you’re generous with the butter or sauce, but if you are a person with refined tastes such as myself (and by refined I mine childish), then pasta is perfect just plain (hello alliteration!) When served plain, 1 serving provides almost 200 calories, and 39 g of carbohydrates, none of which come from sugars. The make up is pretty much the same as rice with a tad bit more fat and a tad less protein. Either way- GOOD STUFF. I’d be lying if lunch and dinner on two separate days this weekend weren’t simply big bowls of plain pasta.

3. Kellogg’s Rice Krispies. I’m a cereal gal. I could eat all day, every day. Every meal, every snack, give me cereal I’d be happy. With milk, without milk. Don’t care. I will ALWAYS welcome cereal.  Back when I was in a dorm and had a meal plan, if I didn’t feel like walking (all of 3 minutes) to the dining hall, it would be cereal for dinner. And if I didn’t have milk, it was generally cereal out of the box for dinner, because going to get milk was almost as much hassle as getting “real” food from the dining hall. ( Yeah, I know, I’m a lazy bum, I got that) Anyways I think you get my point. I never really considered it particularly nutritious, but believe it or not, rice krispies are full of carbohydrates. They boast a 91:2:7 carb:protein:fat percentage ratio, with each serving providing 128 calories, 28g of carbohydrates (3g from sugar), and almost 300mg of sodium. I specify sodium, because I don’t get close to enough sodium in my diet. I’m not a huge meat eater a lot of the time, and I only really use salt with fries (which I avoid), so I don’t come close to the recommended 2500 mg a day. I’d barely get that in a week!

4. Potatoes. Oh man, talk about superfoods. Potatoes are fantastic! Just fantastic. If you’ve noticed, they’re in most of my recipes for a reason. They’re a staple of my diet (and now it’s not hard to figure out where I’m from, I bet), and for good reason. They 93% carbohydrates with very low fat content. 1 serving provides about 260 calories, 60 g of carbohydrate, and a whopping 72 mg of sodium. Warning: this is quite a high sodium content, which can be dangerous who are getting sufficient amounts of sodium elsewhere in their diet. If you have significant sources of sodium elsewhere, just beware that potatoes are a big source. If you’re like me and not getting enough sodium, potatoes are just fantastic.

5. Grapes! These fruits are made up of almost entirely carbohydrates. Now- the downside to them is  that most of their carbohydrates come from sugar (they’re simple carbs) but they are a great source of vitamin C, and if you’re not eating any other sweets regularly, then you don’t really have anything to worry about.

Ok those are my top 5. I’m not a particularly sophisticated eater so these are kind of the basics, and the most you’ll see in my apartment. I don’t have a wide variety, but I eat a hell of a lot of what I have 🙂

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