John Chapman asked:
How many calories do you need to replace the tissue lost when you give a pint of blood away?
We put this to Professor Adrian Newland:
Adrian - About 650 calories, which Iím reliably informed is 3 Mars bars.
Chris - Why would it take energy to replace blood?
Adrian - Anything that develops tissue requires energy.
Chris - So what youíre saying is you just need to put the energy back in.
John Chapman asked the Naked Scientists: My question is about becoming a blood donor as an aid to losing weight. Making body tissue uses a lot of energy (which is why, when young teenage boys hit a growth spurt, they often eat ravenously yet become slimmer while at the same time gaining height). I once read in pro-vegetarian literature that every kilo of food meat requires the consumption of 10 kilos of plant material to create it. Around a 10:1 reduction of energy to create tissue. So can you tell me roughly how many calories it would take to replace a pint of blood? Could you please quantify this in terms that every dieter can understand, such as the number of Mars Bars or portions of chips that is cancelled out by replacing a pint of blood every 16 weeks. Many thanks, John What do you think? John Chapman, Wed, 5th Nov 2008
The limiting factor for a vegetarian would probably be the iron. Bored chemist, Wed, 5th Nov 2008
According to the Mayo Clinic...
Is the 650 calories burnt or lost, or is it that it takes 650 calories to replace the pint of blood or does the blood taken = 650 calories in value?
You could always buy some leeches or get a tap fitted.
The ethical issue is in telling people an incomplete story. People want to lose weight and might not be aware of the dangers associated with too much blood loss.
Thanks sophiecentaur, you seem to understand what I was on about and replied better than I could.
There are two factors to consider whole blood or plasma donation? In the united states you can only donate whole blood once every 56 days due to the time your body needs to replace the red blood cells. I think that would be the type that is approx 650 calories to replace. Plasma would be significantly less I think due to the fact that its mainly comprised of water, platelets, and nutrients. Anyways the Gatorade they give you usually with the donation should cover the initial caloric loss. croltz, Sun, 1st Apr 2012