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Old Forum Why eat fat?

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Matt

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I was wondering why we would need to eat a lot of fat considering our body has so much of it as an energy reserve.  I understand obviously that from a nutritional point of view we would need to eat some - so getting past that point.

To put it simplistically, as I understand it, to get the body to use fat as an energy source, it is easier when you are in ketosis.  To get into ketosis you have to keep the carbohydrate levels low - once there you then (eat protein) eat fat.  Yet the emphasis is on keeping the ketosis happening (ie. low carb) but not really giving consideration to the amount of fat.  So you could have a variable energy input, predominately from fat, either a high energy input or a low energy input.  And the body seems to manage this fine either way when eating like this.

But is there a lower limit to this fat input?  I understand obviously there would be (starvation).  But it doesn't seemed to be talked about.  As it might come down to a handful of nuts a day?

When I've read information on low carb/high fat diets to understand (on a simplistic level) how they "work", they seem to be promoting the eat-what-you-like side of it, ie. go nuts with the nuts.  Yet the energy available to the body from body fat is pretty high (and that is why eating like this is obviously better - massive source of constant energy) and then further eating more fat is giving you a more quickly available source of more high density energy - so you'd think it would be possible to actually eat quite little fat (when in ketosis).

A purely theoretical curiosity, not really something I need to know to train/live.
 
Why would you want to reduce your fat intake? Your body needs to replenish energy from somewhere.
 
Matt, there is a lot to read on this subject on the Internet already.  Google things like "do we burn fat for fuel" and similar and do some reading.

-S-
 
Thanks Steve - yet you've just made this whole forum redundant, perhaps unintentionally??
 
Matt,

Here is the big thing you are missing. Caloric intake (and in some ways specific macronutrients) determine two important things:

1. Resting metabolic rate. You certainly can restrict calories and use stored fat for fuel, but your metabolic rate will begin to drop after several days of severe caloric restriction. This is why having s substantial amount of calories is needed. You might have the storage, but your body is not willing to just let it all go.

2. Appetite: hunger is a specific response to caloric restriction for a reason.
 
Matt, no offense intended, sorry that offense was taken.

-S-
 
Steve - no offense taken.  I was just wanting to start a discussion (even though I may not be ignorant on the subject).  My inspiration was something I read about ancient Greeks and how they knew the "secrets" of tapping into the "unlimited" reserves to do heroic acts of their legend.  And another book I have, along with the google search you just mentioned.

The first page I read, and I assume a lot are the same - recommends the typical low carb for ketosis (I never knew it was to help treat epilepsy) yet high fat.  Everyone loves that part (the high fat) - tastes great - but I was just wondering.  If you are an athlete - say a fighter needing to keep the 66kg weight class - I wonder how scientifically you could manage your weight on a high fat diet.  I remember reading about Lance (Armstrong) and how he would weigh his food to keep himself lean - and he was in the saddle 8 hours a day!

Anyway - this topic may be over-done on the forum?
 
http://www.marksdailyapple.com/are-elite-athletes-inadvertently-training-like-grok/?awt_l=4wtwQ&awt_m=JcStVvjMixWvYa#axzz3ZCtV91O9

......may help answer some questions. The pdfs highlighted within the article provide more of the science. Aimed at endurance athletes, as the link suggests, so would that apply across all athletic pursuits?? Maybe that is your question. And then there is what is good for an elite endurance athlete versus health and fitness generally versus strength versus lifestyle and how it all comes together for your goals.
 
Matt, I eat a high fat diet and I compete at 67.5 kg.  Eating healthy fat doesn't make you fat.

-S-
 
Thanks Alistair, I'll have a look.

I don't want to repeat my first post but it seems to be unclear to most (ex-Scientist).  I am not wanting to lose weight etc. - I mentioned that this is an intellectual discussion.

But yes - I do eat a high fat diet - not worried about that or the health side of it.  I was just pondering it from an objective point of view.

To put my first post in an analogous question - if I was to kayak from home to San Diego, and could only stop at Hawaii for supplies: what would be the best ration pack to take and then re-fuel with having limited carrying capacity?

Ie.  the most efficient means to eat a high fat diet if forced to.  It is very forgiving so to speak, as we know (meaning you don't have to try to hard, and its easy to eat enough fat) along with our riches of available food - yet if we had severe practical constraints, would we perform the same (ie keep our energy levels at their peak)?

Or I could ask a similar question other ways (fighting weight/Lance etc).

And a perhaps different question - eating for optimal power production.  Something I haven't really thought too much about (until wondering why I have apparently been unclear with my first post of this thread).
 
Matt,

I'm sorry, but the question is still not coming through clearly. Are you just asking what food will have the highest energy density (pure fat)? For the second question regarding power production: some carbohydrate is needed for muscle glycogen synthesis. Ketogenic diets may work fine for endurance athletes and those seeking weight loss, but some carbohydrate is needed for maximal power production. I enjoy a cyclic ketogenic strategy most of the time.
 
The higher the work output, the greater reliance on carbohydrates VS fat.  This is an adaptable system though.  A high fat diet can shift the fuel crossover point (when the body starts to use more carbs than fat) to higher intensities.  However, if the goal is high power output, the preponderance of the evidence favors at least a moderate carb diet.  For ultra endurance, it is probably a wash, with high fat possibly better if adapted adequately.  Fat adapted ultra endurance athletes can run for 12-20 hours with 90% of the fuel coming from fat.  Whether this is optimal is still in question.  More research is needed.
 
Hi Mike,

Thanks !  I remember reading something you've written in the past about this and liked it.  I often end up at the "more research" part of our understanding - are you involved with this?
 
Sorry Scientist - I'll maybe just outline the logical line of thought quickly - the aim is to use body fat for energy.  Low carb helps you get to a state where you're more pre-disposed to.

Then normally it is recommended to eat high fat - odd as you want to use your own fat reserves, so why would the body do that when it has all it needs in the blood from digestion.  You'd think you'd want to eat less fat so you are forced to use your own body fat.

So questioning (firstly) this boundary - hence the title "Why eat fat".  Taking a principle to the extreme obviously to understand it better.
 
Matt

I am not involved in that type of research....yet.  Might be part of my second career after I retire from the Navy in 402 days.
 
Matt

To clarify a bit.  Most high fat diets end up being high protein.  Not all of course, but most.  The end result is that this type of diet has a high satiety effect, so people spontaneously reduce their caloric intake.  High carbohydrate diets tend to produce less satiety, so people spontaneously eat a bit more.  The effect is not big but it adds up over time.  The other reason that high fat diet proponents recommend eating fat to burn fat is that pre race meal composition can have an effect on what you burn during a race or event.   For a person on a high fat diet trying to lose weight, a calorie deficit is still necessary, but can be easier to achieve due to satiety.  Some people do not lose weight on a high fat diet.  Obviously they are not achieving a calorie deficit.  Whether a high fat approach is better long term is hard to say yet.  For more background Google Peter Attia, Jeff Volek and Steve Finney.  Peter Attia has a couple of good TED talks.  His youtube video from his talk at the Institute for Human and Machine Cognition is especially good.
 
Hey Mike,

I was thinking this morning that a couple of steaks would fix everything! then I read your post.  I can see how the high-fat becomes in reality high-protein.

But you've got me thinking and thanks for clarifying it a bit more.  I thought it was a bit more simple than that - ie. to become fat adapted so one can tap into their own fat reserves more quickly. I was under the assumption this is what the goal is when going low-carb-high-fat : yet in this thread I was questioning if this is what is actually being achieved (when going low carb and high fat), and maybe it is not as clear cut as I thought. I have Volek's book which I skimmed then got distracted.  Will have to re-visit it.  Maybe in 402+ days I'll be reading one of yours!

You'd have so much experience I'd imagine you'd be a goldmine in retirement.

As an aside - I would have thought the military would have worked this out a long ago - as it seems to be essential ancient (but lost) military knowledge ie. the essential ability tap into the "unlimited" supplies of bodyfat/energy to perform at a peak ie. fight and kill after a long journey.  This to me would represent my two questions you've touched on - endurance and power.  Not that I need or want to go the full-viking.  I just questioned myself one day, why my pre-dinner snack was more energy dense than my upcoming dinner.
 
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