Muscle Atrophy

[tis]

Hello everyone,

I was chatting to a friend of mine about cutting the other day and explaining some of the things I'd learnt on here. However, somehting struck me that I've been wondering about since. I talked about not actually needing to do cardio all that much provided diet was below maintenance etc etc also eating plenty of protein to prevent muscle loss etc.

The issue i'm bothering about is: if someone's eating enough protein to minimise catabolism and is say 300cal below maintenance. Why would eating say 500-800 below maintenance increase catabolism. The logic, I guess, was your body is utilising fat as a energy source (of which there is presumably plenty) and there's plenty of ingested protein to use before muscle is utilised. So why would eating fewer cals (without dropping protein) affect the amount muscles are broken down for a food source? If i've not explained that very well I'll summarise - if there's lots of protein (food) & lots of fat (belly) why would muscle protein be required?

The only explanation I can think of is that there is likely different things the body needs which can be obtained from excess muscle, esp if the protein was from a limit number of sources, or perhaps, that everything is likely to be broken down to some extent and muscle might be preferable for the body if it's running low on fat but has plenty of muscle.

If anyone could offer an explanation to my ignorant self it'd be great!

Cheers folks!

[James]

There is only so much fat that can be mobilised and burnt off from the body as energy over a period of time, therefore, fuel will be sought from elsewhere in either the body as a whole, or additional calories from foodstuffs.

[Wotan]

As above. Hormonal/enzymatic release of fat stores is a rate-limiting factor (these are bypassed when eating fat, although other enzymes then come into play). The rate of metabolism of fat from both sources is increased by simply getting the body used to eating fat. Eating fewer and fewer carbs, basically, because high carb diets effectively shut off fat useage.

Running a marathon on fat (as opposed to carbs) is not a problem because there a nine calories per gram of fat compared to only four in glucose (which all carbs basically get converted into before use) and the rate at which you can burn fat is easily managed by the body when its accustomed to using fats.

The situation you are referring to occurs in "high-carbers" - which is pretty well everyone since very few of us (Nu excepted) are carb-free. Were you to be like Nu the conundrum you describe would not pertain.

So how come all "low-carbers" and "carb-freers" are not built like water butts? The answer is that ingested fat initiates a feed-back loop that causes the hunger signal to cease (repletion). This is not the case with carbs. They are, for a variety of reasons, addictive in their nature and untouched by the feedback mechanisms. Few people will overeat on a protein and fat diet, half the Western world is actually clinically obese on a protein and carb diet.

Hope this helps.

[tis]

Very informative, thanks guys!

[roadz]

Quote

As above. Hormonal/enzymatic release of fat stores is a rate-limiting factor (these are bypassed when eating fat, although other enzymes then come into play). The rate of metabolism of fat from both sources is increased by simply getting the body used to eating fat. Eating fewer and fewer carbs, basically, because high carb diets effectively shut off fat useage.

Running a marathon on fat (as opposed to carbs) is not a problem because there a nine calories per gram of fat compared to only four in glucose (which all carbs basically get converted into before use) and the rate at which you can burn fat is easily managed by the body when its accustomed to using fats.

The situation you are referring to occurs in "high-carbers" - which is pretty well everyone since very few of us (Nu excepted) are carb-free. Were you to be like Nu the conundrum you describe would not pertain.

So how come all "low-carbers" and "carb-freers" are not built like water butts? The answer is that ingested fat initiates a feed-back loop that causes the hunger signal to cease (repletion). This is not the case with carbs. They are, for a variety of reasons, addictive in their nature and untouched by the feedback mechanisms. Few people will overeat on a protein and fat diet, half the Western world is actually clinically obese on a protein and carb diet.

Hope this helps.

A good post, but I think the OP was referring to body fat as opposed to dietary fat...

[Wotan]

The first two paragraphs included body fat. I included ingested fats afterwards just to give a more rounded picture to save anyone having to ask more questions afterwards.

[tis]

Does anyone have any info on just how much body fat can be utilised before catabolism sets in?
is there an amount of fat that can be used above which only muscle tissue will be utilised or will the muscle tissue be used in conjunction with fat after the point at which fat alone is utilised?

What I'm trying to ascertain is just how detrimental over dieting is. My logic being, it might well be possible to diet for say 6 months without losing and muscle mass but if the muscle mass that would be lost in 3 months of stricter dieting could be replaced in say two months of relatively 'clean' bulking, the natural desire not to want to lose muscle might be misplaced.
Any thoughts?

[Martin Brown]

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The issue i'm bothering about is: if someone's eating enough protein to minimise catabolism and is say 300cal below maintenance. Why would eating say 500-800 below maintenance increase catabolism. The logic, I guess, was your body is utilising fat as a energy source (of which there is presumably plenty) and there's plenty of ingested protein to use before muscle is utilised. So why would eating fewer cals (without dropping protein) affect the amount muscles are broken down for a food source? If i've not explained that very well I'll summarise - if there's lots of protein (food) & lots of fat (belly) why would muscle protein be required?

Just adding some logical thought rather than science here - your last sentence cannot be true on a large calorie deficit. There simply isn't lots of food

Answering your above post - the big problem with over-dieting and losing more muscle is that it isn't that easily regained. Dieting properly and maintaining a good level of muscle and a healthy metabolism for slightly longer will see better results in the same timeframe as overdieting and then trying to 'bulk' to regain lost muscle.

I'm not sure on the biology behind it tbh but there are hormonal repsonse systems at work that control how much fat you burn and your metabolic rate as a result of weight loss / calorie restriction. Going too low on cals doesn't have a very good effect!

[tis]

Thanks for the info

[NU_nutrition_TS]

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Does anyone have any info on just how much body fat can be utilised before catabolism sets in?
is there an amount of fat that can be used above which only muscle tissue will be utilised or will the muscle tissue be used in conjunction with fat after the point at which fat alone is utilised?

According to the many 'starvation' studies that have been performed and reported on in journals over the years, there is an initial catabolism of the muscles, but after a few days this gives way to mainly fat usage. It is only when all available fat has been used* that the body reverts to breaking down its muscle for energy - at which point death shortly ensues. If you have reached this point, even rapid re-feeding can be detrimental (much research on this gleaned from observations of food aid given to starving third-world populations).

Intermittent fasting and low-carb/ketogenic diets are meant to optimise the fat usage that results shortly after the onset of starvation and prolong it without causing the overall body-wasting, ill-health and death that would result from outright starvation.

*That level would be the 'essential fat' level - given as ~5% total bodyweight for adult males. This may explain the necessity for dietary carbs when seeking to reduce body fat percentage to single digits - since the level being sought is at or below the 'essential level' (that absolute minimum the body needs to maintain for survival), it is more likely the body will turn to muscle catabolism to provide the energy (particularly glucose for those cells that cannot utilise fats/ketones) it needs.