Wasted youth, or selective muscle loss?

I would imagine it saves the heart muscle until last

first14808 said:

So I've been thinking, which can sometimes be a dangerous thing..

An argument against fasting sometimes seems to be that it results in muscle loss. So I'm curious how selective our bodies are about where they'd scavenge protein from in a starvation situation. I'm assuming from an evolutionary perspective, it'd be sensible if that were selective in some way, but curious if that happens, or is possible.

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So your body carries around about 40,000 calories in fat stores (that's for a "normal" weight person) is it really going to be so stupid as to scavenge muscle as a primary source of energy?

first14808 said:

Exactly, but it's something I keep seeing repeated, especially in relation to fasting.. Where it's even less likely if it's intermittent or short term. It's possible via gluconeogenesis, but not energy efficient, especially when there are better sources like our fat reserves. So I doubt it's much of a risk in anyone without extremely low body fat, or over a short period. I guess if we're deficient in other nutrients like amino acids for a prolonged period, it might be more likely.

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Indeed context is all... there may be a max number of calories that we can extract from body fat per day although I doubt if that has ever been looked at.. Also some think that the lean mass we lose when fasting is in fact the old dead cells that are culled via autophagy and then replaced with shiny new ones when we eat again. The study is in its infancy but I can't imagine the human race has survived for hundreds of thousands of years without the ability to skip a meal or two and not collapsing on the floor in a heap of muscle free jelly. Sometimes scientists just can't see the logic for their own dogma..

I think the problem may be linked to athletes and endurance ones most of all, where the low blood glucose can lead to the muscle scavenging from the local cells around to supply energy surge, Looking at the Krebs (Citric) cycle, then muscles can store glucose from blood as local glucogen, or use glucose direct from blood, or use stored glucogen previously stored in the local cells, But the local stores fo not hold much, and the liver is signalled to release some from the adipose tissues - but this takes time to happen, and so there may be a larger demand than can be locally provided, so the body burns what else it can find, such as ketones or raid other nearby cells.

So I suspect it is the cells nearest to the active muscle bundles that get scavenged, and only under extreme duress while blood sugar levels are low in the blood, I am thinking of Paula Radcliffe during the Tokyo Olympics during the marathon walking event, Maybe Tim Noakes has a better handle on this aspect.

I wish I hadn't been stitched up by work, I wanted to see if my muscle mass would come back fully after a week, but have not managed to get to the gym at the right time to measure i.e. without taking on fluids or like today a networking meeting, where I had salmon and eggs. This morning will be no better with networking at 06.30....then travelling to Oxford in the evening....paintball on Sunday, so Monday is my next opportunity.

Anyway, I gained muscle 0.2 between days 1.5 and 2. Then dropped about 0.75 kg a day for a total loss over 91 hours of 1.6 kg.

As the graph shows I gained about 0.6 kg a day back, so by now I should be even.

Mbaker said:

I wish I hadn't been stitched up by work, I wanted to see if my muscle mass would come back fully after a week, but have not managed to get to the gym at the right time to measure i.e. without taking on fluids or like today a networking meeting, where I had salmon and eggs. This morning will be no better with networking at 06.30....then travelling to Oxford in the evening....paintball on Sunday, so Monday is my next opportunity.

Anyway, I gained muscle 0.2 between days 1.5 and 2. Then dropped about 0.75 kg a day for a total loss over 91 hours of 1.6 kg.

As the graph shows I gained about 0.6 kg a day back, so by now I should be even.

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As a matter of interest how did you measure LBM? Was it TOBEC ot change of body fat percentage or by girth measurement? None of these methods seem to be selective, so only give a general body mass picture which is not quite an answer to the OP who wonders if muscle mass is scavenged locally or generally.

If fasting leads to weight loss then this will primarily be glucogen and water from the muscle cells initially, and then from the adipose fat stores So initially the muscles will lose mass as water is excreted and glucose burnt off, so a drop in LBM is not unexpected. However as adipose fat is depleted then the body weight will drop too, and will appear as LBM increasing I think the BF scales that measure electrical conduction really measure fat stored in muscles, and are not so affected by adipose tissue fat loss - that needs an MRI scanner to measure adipose fat (as used by ND study)

first14808 said:

So I've been thinking, which can sometimes be a dangerous thing..

An argument against fasting sometimes seems to be that it results in muscle loss. So I'm curious how selective our bodies are about where they'd scavenge protein from in a starvation situation. I'm assuming from an evolutionary perspective, it'd be sensible if that were selective in some way, but curious if that happens, or is possible.

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Great question.
Imagine you are a car - a car that can make alterations to its size, engine size and the amount of luggage it carries. The objective of the car is to get to the next stage. To do this, it need fuel.

Suddenly, fuel becomes limited. (You are fasting.) What do you do?

You could loose the luggage - all that excess weight which makes you feel secure (comfort eating??? = bare with me) and none of that luggage contributes to fuel efficiency. Loosing the luggage from the boot or the roof rack would improve efficiency and make your fuel last longer. But who wants to throw out their stuff.

You could reduce the size of your car, but it's not easy loosing your frame. Who can reduce their skeleton grom 6ft 2 to 5 ft 8???

You could reduce the size of your engine. You would probably have to loose some luggage at the same time. Smaller engines go further but would be under a huge amount of strain if the size of the car or the amount of luggage is not reduced. Try sticking a 1.1 litre engine into a fully laden people carrier and see what happens.

So now let's look at the human body.
Reducing engine size is quite easy - i.e. reducing muscle mass. It only take 1 week out of the gym and I notice that my clothes feel baggier on me, but make the engine too small without reducing the luggage and you will end up with problems.

Smaller muscles use less energy - you tend towards sluggish. Carrying all the excess luggage (fat0 will only make the problems worse. Follow this to its natural conclusion and you could end up with a body composition where fat is higher than muscle mass - in other words your car is overloaded with luggage and the engine is too small. you will never reach your destination - or if you do, you will not enjoy the ride and your health/well being will suffer.

Which muscles waste first - that depends - we have to assume there is some level of exercise, using legs, arms etc. First thing to go with me - even in just one week off - the shoulders. There are no natural movements that take the place of heavy shrugs or shoulder presses and unpacking the groceries doe not even come close.

The best way to do the type of fasting some diabetics follow, is to combine it with exercise - tell your body you need the engine and just jetison the luggage.

PS - big muscles use more glucose and help with blood sugar regulation.

I train for strongman 5-6 days a week. I don't fast. I take 1-2 weeks off every 6 weeks - to recover and stop from going stale. My plan for staying alive is very dependent on not getting bored with exercise. I'm 53 and still get excited about going to the gym - every time. (T2 Oct 15 - met, exercise and diet, not fasting - complete opposite in fact!)

Sean

I think, as someone who looks at the world and asks.'why'.

I think everybody is right. The 2 human evolutionary aces are adaptability and self awareness. You can argue the thumbs and talking if you like.

If you are not getting food/deliberately fasting then say you haven't the energy to get out of bed. That is somebody turning the engine off.

As I understand it the body will destroy its self in an effort to survive sacrificing what is deemed non essential.

Our hands get cold because the body keeps the warm stuff for the important bits like the heart etc.

Same with the skeleton. Fingers break before the wrist, wrist goes before the elbow etc.

I think it depends on your body and it will decide what, when and how much it needs. As best it can.

Think war of the worlds, we have eons of evolution before carbs and easy food.

Oldvatr said:

As a matter of interest how did you measure LMB? Was it TOBEC ot change of body fat percentage or by girth measurement? None of these methods seem to be selective, so only give a general body mass picture which is not quite an answer to the OP who wonders if muscle mass is scavenged locally or generally.

If fasting leads to weight loss then this will primarily be glucogen and water from the muscle cells initially, and then from the adipose fat stores So initially the muscles will lose mass as water is excreted and glucose burnt off, so a drop in LMB is not unexpected. However as adipose fat is depleted then the body weight will drop too, and will appear as LMB increasing I think the BF scales that measure electrical conduction really measure fat stored in muscles, and are not so affected by adipose tissue fat loss - that needs an MRI scanner to measure adipose fat (as used by ND study)

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I am using the Boditrax system (Tanita Scales) at my David Lloyd gym. It appears that this has become the standard across major UK gyms as an internet search shows Virgin, Puregym and others are using this also. For me, this is excellent, as I believe this is the best system (also can pull in Fitbit bottom lines). They will not like me saying this but this high end kit reads the same as their £35.00 and £150.00 home and semi-pro units.

I use these types of measures as a reasonable guide, and know in my case they are somewhere near right due to the six pack at under 10% (i'm now at circa 11.5%) and I cross reference with Nokia and Fitbit scales.

first14808 said:

Hmm.. Maybe also add 'Always singe your mammoth downwind'. But a reasonable catchphrase, although I'd say it's staying healthy, not just fighting diabetes.

I suspect the answer's still general loss, but muscles that are used the most often get spared, ie signalling for nutrition to replace or grow new fibres. I do think there are some myths around muscle loss that might be more to do with gain or loss in tone rather than absolute quantity. It's a bit like the 6-pack diet & exercise guides that don't mention the easiest way to 'gain' a 6-pack is to shed the body fat concealing them, and 'spot' fat loss doesn't really work.

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During fasting and semi-starving regimes I do not lose my muscle, as far as I can see, and as far as I can feel when lifting heavy things (which I do on a daily basis). I have been semi starving for six weeks at the moment. My muscles have not diminished. I use them, daily, they continue to be good, big for my gender and age, and they do not diminish or depart or stop working well. In short, I don't lose muscle. Body fat yes. On my feet, on my fingers, on my face, around my neck, on my back, oh yes around my gut which is the target of course. But my muscles have not gone down. Arms, abs, and my leg muscles - my strong point - all good.

Having general energy is another thing. When eating not enough I find I have to confine physical exertion to just after I have eaten the pitiful amount I can eat. So spurts of activity. (Just like going hunting and gathering would have been like in times of food scarcity, which is what NDs/BS diets/fasting regimes is attempting to emulate in the good cause of good health and fitness.)

Hahaha, re the mammoth. I am very happy to use the phrase "ancestral diets". The Paleo diet is good for dealing with the big causes of digestive/food issues and high glucose and insulin - wheat, dairy, legumes. And for re-introducing healthy fats into diets and bodies being destroyed by the high carb low fat regime.

And I mentioned fighting diabetes due to this being an interest group forum - for folks with diabetes. But I get your point. I assume that everyone here doesn't want to die too early, and diabetes can do that to you. Which is why the battle metaphor is used, if in the mood. I haven't eaten properly for six weeks, so I am in the mood for battle perhaps rather more than usual . Good thing I still have good muscles.