Is a fat-augmented near-fast just a low-calorie diet that will slow metabolism?

#1

Hi. I have a 9 day camping trip coming up and am planning on doing some kind of fast or near-fast for 10 days.

Now, I realize that the purest or “hard-est core” method would be for me to fast (water and salt and black coffee only). That would lower insulin the most, stimulate autophagy the most, maximize fat loss, maybe help reduce cancer risk. And if I want to lower cortisol the most, I could give up my black coffee (caffeine stimulates cortisol) and switch to green tea (lowers cortisol because has a chemical that blocks the enzyme that converts cortisone to cortisol, also has enough caffeine to prevent me having withdrawal headaches).

So my aspiration is to do a fast with water, salt, and green tea. (If I can make it).

But I have a nagging question for you all:

Richard has blogged that the body can only mobilize 31.5 grams of body fat per pound of excess body fat. I am 6’1” and 215 lbs, BMI says I should be about 180, so 35 lbs of extra fat. So my body fat will only supply about 1,100 kcal a day for me to live on.

I am worried that I won’t have enough energy to do my camping activities.

Now, If I guess that I burn about 2,000 kcals a day, then that means I would need to supplement 900 kcal from another fuel source. I am ketoadapted (so carbs are not an option), so let’s say I add MCT oil to the above fast.

So now my planned fast becomes a fat-augmented near-fast, that is, I would ingest only water, salt, green tea, and about 900 kcal of MCT oil per day for 10 days.

Sounds like a plan, but isn’t this just a low calorie diet? (A fat-only, 900 kcal a day low calorie diet.) And don’t we know from Dr. Fung’s blog and videos that low calorie diets always lower your metabolic rate and sabotage your fat loss? And don’t we know from Dr. Fung that fasting does not burn protein but low calorie diets do? (Notwithstanding the Dr. Fung-Dr. Phinney controversy).

So, should I do the “fast” (water, salt, green tea), and just risk feeling tired?

Or should I do the “fat-augmented near-fast” (water, salt, green tea, MCT oil), and risk slowing down my metabolism?

#2

Great post with a great question. I hope that you get a great answer!

(Adam Kirby) #3

I’m thinking more and more that Jason Fung has scared people too much over metabolic slowdown. The key seems to be if you’re keeping lipolysis activated w/ low insulin level. What he is talking about is people who calorie restrict while keeping their insulin high with crappy carb food/many meals a day. I would think, if calorie restricted but pulling adequate energy from fat stores, no, your metabolism will not slow.

(G. Andrew Duthie) #4

I would argue that you have it backwards. If you do a water-only fast (i.e. no supplemental fat) that is where you risk slowing your metabolism, because you will not have sufficient fuel available from body fat to supply your daily metabolic needs. If you supply additional fat, you should be less likely to slow your metabolism, because in the absence of insulin signaling (i.e. - carbs and protein), you’re still basically in fasting mode.

@richard may have more on the topic…

(Duncan Kerridge) #5

You need to estimate your lean body mass, not BMI - that will include maybe 15% body fat. I’m 6’3" and my lean body mass is around 150 I think - a guesstimate from some online calculator, try this one : http://www.calculator.net/lean-body-mass-calculator.html

Tldr : you probably have plenty of fat to fast

(Roxanne) #6

I’d also question what 900 calories of MCT oil only is going to do to your digestive system - might we worthy trying out at home first while you have bathroom facilities close by!

#7

This is a very interesting point! I wonder what Dr. Fung (and other experts) would say about it. Even for the benefits of autophagy, should a lean and active person be eating the Keyes-starvation-study-calculator calories? @carl

(Sascha Heid) #8

In my understanding metabolic slowdown is only the result of too much insulin, which is usually the case in … everybody.

I’m currently doing a fat-supplemented fast and am about to break through my wall (5 days).

#9

Duncan_K, Thank you. This is very helpful. The calculator says my lean body mass is about 144.1 to 154.3 to 158.4 lbs. So 215 minus 155 = 60 lbs of fat, times 31.5 equals 1,890 kcal of energy for body fat accessable per day (at the start, that is).

So you are right: It looks like I can go for the hardcore fast (water, salt, green tea) and do fine. (I forgot to say I also take magnesium pills).

But I would still like to know the answer to my original question, that is, if someone doesn’t have enough body fat to supply their daily BMR, should they fast, or do a near-fast with supplemented fat calories (to prevent a decrease in BMR)?

Thanks,
-Jon

#10

Good point. I just checked the MCTLean website and the MCT oil has 100 kcal per tablespoon. So I would be eating 9 tablespoons per day! Even if spread out throughout the waking hours, that might not be tolerable.

(Jen Andrew) #11

Dr. Ron Rosdale said fat does not interfere with authopagy. Protein an carbs do. If you look at YouTube videos with Ron Rosdale he shows studies to back it up. I hope that helps :slight_smile:

(Dany Bolduc) #12

Be warned, this is full of speculations and ramblings

I’m pretty sure Jason Fung has stated that he does not subscribe to the idea that the daily availability of stored fat is limited to 31 kcal / lb.
(Only from listening to his Fasting Talk podcast with Jimmy Moore, and no other source) I don’t think he ever recommends “Fat Fast” where one consumes many hundred calories.
He does allow for “whatever keeps you going”, but that is more in terms of some cream in your coffee, or some broth, etc.
Meaning “if a minimal amount of calories will keep you going, than it’s better than stopping”.

On the other hand if you believe this limit of 31 kcal / lb / day (which I personally do) then, you do need to calculate, with your lean body mass, how much your body can supply, and supplement up to your BMR (as you proposed to do).

As to the different between Fat Supplementation to meet BMR requirements and a Caloric Restriction I can only offer some speculation:

  •      If one that is not Fat-adapted, then answer seems easy, calorie restriction (without the ability to access fat reserves) most likely start slowing metabolism immediately.

  •      But if you are Fat-adapted, I would posit that there is TWO thresholds to be mindful of, and that it is hard to evaluate them.

I’m saying this because a “quite significant” portion of you BMR requirement is allocated to breaking down what goes down the hatch (digestive processes).

  •      If you "Water Fast", then you cut considerably in your daily energy requirements (I would further propose that this could be a major contributor to the "why we feel so energetic while fasting" (if you have plenty of fat reserves))

o I would say that if your fat reserves suffice to supply (BMR – “digestive process requirement”) then you would not slow your metabolism

  •      If you "Fat Fast", then you cannot discount the digestive process as much and must therefore supplement closer to your BMR.

I don’t know of a formula to calculate the energy expenditure of digestion.
I did hear/read that, with your brain and muscle mass, it was a major contributor to the daily energy requirement.
Does it represent 10%, 25% 40% ? I have no idea. But if you basically turn it off by water fasting, maybe your body can run on lower the ‘regular’ BMR energy without slowing down any other processes.

I would still be wary of water if I was already lean enough. But with the 80 or so pounds of fat I carry, I feel pretty secure that I do not slow my metabolism when I fast.

(Adam Kirby) #13

I think your speculations are very sensible. To me the difference between fat fast and low-calorie diet is “low calorie diet” implies that dietary composition is irrelevant, just low cals. Fat fast implies energy intake with least possible effect on insulin.

(Siobhan) #14

Hmm, good question, here is some speculation on my part:
No protein fat supplementation would not interfere with autophagy as far as broken down muscle, skin, etc because the purpose of this is to supply protein needed to maintain the body - not energy.
So fat would supply energy but not the protein and thus it would continue.
As far as autophagy as in eating body fat the point is youre already at your limit so it doesnt matter

Shouldnt affect insulin much which is one thing that contributes to metabolic slowdown
but as far as if it does slow down MBR at all…I honestly dont know. I will have to see if any studies exist on this.

Interesting question for sure though.

I thonk the answer is no though because your insulin levels will be very low and you will have full access to body fat. So you arent actually eating only 900 calories of food it is 2000. Plus the composition I think would be very important. Your body slows metabolism becayse it feels it isnt getting enough energy, I think one thing that pushes that state of emergency is insulin spiking plus low cal.
Entirely speculation though.

At worst I say you will know because youll start feeling like trash. At that point supplement fat and if it doesnt go away end the fast.

(Dany Bolduc) #15

For me, the big differentiator is Fat-Adaptation.

Low-calorie in a non Fat-adapted state is depriving your body of the energy it needs. It will invariably slow your metabolism.
Low-calorie (intake) in a Fat-adapted state is NOT ‘low calorie’ (and that’s a critical difference), your fat reserves supply the energy missing from your intake.

When fasting:
If already fat-adatped, you don’t skip a beat, you actually get a surge of energy (my speculation is that this is whatever energy your metabolism usually allocation to digestion)
If you are not already fat-adapted, 1) it’s really hard because you become very hungry and 2) you body quickly start turning off non-essentials (slowing metabolism)

And of course, to be and remain fat-adapted you must follow a Keto diet with minimal dietary carbs.

PS: I know there are other things at play with fasting. like adrenaline, testosterone and growth hormone surge. And the fact that it gives a nice break to your digestive system and pancreas and others. But my main point is that Fasting in a fasted state is NOT ‘extreme energy deprivation’, quite the contrary.

(Karen Fricke) #16

I do water, tea, and salt only. I’m hungrier if I add fat. Richard is probably right about the limits on calories from body fat, but don’t forget about autophagy, there are calories in the excess skin and connective tissue associated with the fat. Try either one and see how you feel. I’ve heard Dr Fung’s podcasts, he suggests not having added fat and that low calorie messes with metabolism more than no calorie. Pay attention to electrolytes, when I feel like I needed to eat, salt and water usually takes care of it.

#17

UPDATE: Two weeks before the camping trip I tried to do a 2 day water fast. Failed. Made it to 44 hours and then ate for some reason. So that following week I just went back to my normal keto 20:4 IF diet.

The next weekend, (one week before the camping trip) I tried again to do a 2 day water fast. Made it. Then… just kept going. So today is Friday, I am on day 7 of the water fast, and the camping trip starts tomorrow.

Funny how you’re not ready until you’re ready.

I am only a few pounds from becoming a resident of “Onederland” (a body weight starting with a one) so I plan to just keep going with the fast during the camping trip. This really is a golden opportunity for me to do a prolonged fast, because I won’t be around my kitchen, the restaurants and supermarkets of my town, and I won’t be doing any eye surgery while on vacation. I am always reluctant to do surgery during a fast, just in case. If a patient were to learn that I hadn’t eaten for a couple of weeks on the day I did their cataract surgery, I don’t think they would be very understanding.

As my fat reserves decrease, I might start eating MCT oil daily to prevent my body from looking at my muscle protein with an eye toward burning some.

We’ll see…

(G. Andrew Duthie) #18

Awesome. Congrats!

The first 48 hours tends to be the hardest, and if you haven’t experienced that, it can be very hard to push through. And that’s OK. As others have observed, fasting is like a muscle, to some degree. Practice makes it easier.

Just remember to listen to your body. If you start to feel overly cold, or lousy, it’s OK to eat.

And given that you’re going camping, I’d recommend having some fatty foods on-hand in case you decide to either break the fast, or supplement with a little fat to continue on a modified basis.

Good luck, and good job!

(Duncan Kerridge) #19

Great stuff Jon!

I’m on day 3 of a fast doing just this and you’re right I do feel a lot less hunger pangs than my previous three day fasts where I have added fat. Right now I’m thinking of stretching it out a couple more days.

#20

Someone with few lbs of body fat, or inaccessible body fat due to high fasting insulin, would be best to have some fatty food handy in case they show signs of slowing metabolism. Generally most people can get through the first day or two by using up their readily available energy supplies even with limited access to adipose. After that, it’s a matter of knowing your signs of metabolic slowdown. Lethargy, cold hands and feet, mental fog etc are all things I watch. Then I’ll supplement some fat.