Burning Calories Donating Blood
May 6, 2005 4:31 PM   Subscribe

While donating blood today I noticed a sign that says "You burn about 650 calories by donating blood." How is that?

Do you burn them just through the donation process?
Do you burn them replishing your blood supply?
I asked the nurses at the blood bank and none of them had any idea, the one who put the sign up told me she just read it on the internet.
posted by thefinned1 to Health & Fitness (9 answers total)
The Mayo Clinic has the same assertation. Not a good answer, but I definitely wouldn't argue with them.
posted by bh at 4:36 PM on May 6, 2005

Well, the Mayo Clinic says the same thing, so there's more credibility than some random unidentified site, but they don't say how.
posted by DevilsAdvocate at 4:37 PM on May 6, 2005

I don't know for sure, but logically, it would take a significant amount of energy for your body to replenish blood. (I know a woman who lost almost 20 pounds when she was re-growing a badly burned patch of skin on her foot.)

You wouldn't be able to burn 650 calories by walking into a blood bank, lying down, then eating a cookie and having a glass of juice.

On preview, I saw the Mayo quote too, but could find no facts to back it up.
posted by Specklet at 4:39 PM on May 6, 2005

From the Straight Dope:

"Perhaps blood donation could be promoted as one way to lose a bit of unwanted weight. Taking into account the composition and energy in each component . . . I estimated that one unit of blood reflects about 600 cal of food intake. Hence, a single donation can off-set either 2 hamburgers, 3 donuts, or 5 granola bars. Awareness of these statistics might increase the appeal of blood donation, particularly among healthy adults who are concerned about obesity."

The article goes on to say that this might ad up to about a pound of weight loss per year.
posted by bh at 4:42 PM on May 6, 2005

I'd guess it's that amount to replace the lost RBCs, platelets, white cells, and plasma proteins (clotting factors, albumin, etc). You'd lose a tiny bit of glucose and fatty acids as well, but it's probably more the cell loss. 3500 calories will lose you a pound, but most people eat something sweet after they donate to give their glucose a jolt.
posted by gramcracker at 5:07 PM on May 6, 2005

Yeah, that's got to be it. They're really just being removed. "Burning calories" is--I think--just a really bad term to use.

All the calories in your body basically have to get carried from your GI tract to your muscles through your bloodstream. Taking blood just means that you're siphoning off some of those calories in transit. So, sure, you've got a net deficit of calories after donating blood, but that doesn't mean your "burning" them. You're really just letting them flow out a needle, with the blood.

That being said, I think blood donation is a _totally_ critical responsibility we all share. Give often, please. (Just ignore any silly PR claims about "burning calories".)
posted by LairBob at 5:17 PM on May 6, 2005

Blood donation used to be a critical responsibility I shared. Then they started calling, begging me to donate blood, once a day. They take breaks now and then, but there definitely have been periods at least 2 weeks long where I got a call from them (I stopped answering their number. If I had AIDS I think they would leave me a message.) every weekday.

I've also read that blood donation concerns in general get to charge hefty "handling fees" (it is illegal to "sell" the blood) for each pint.

So I doubt I'll bother donating, at least to these specific scumbags that can't stop calling me, ever again.
posted by TheOnlyCoolTim at 10:52 PM on May 6, 2005

They won't let me donate anymore (tattoo), which is too bad, because i have O- and i'm getting chunky. ;)
posted by schyler523 at 11:45 PM on May 6, 2005

Maybe you burn the calorie's due to heightened 'needle anxiety'.......
posted by Radio7 at 2:16 AM on May 7, 2005

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