Fasting versus very low caloric intake


#1

I’ve asked this question before but can’t seem to get the answer that I’m looking for. I want to understand the biological mechanistic reason that fasting is different from consuming very low calories.

For example, I believe Megan Ramos and dr. Fung so I am embarking on a two-day fast with just black coffee and water until dinner time Wednesday. However I’ve been intermittent fasting eating one meal a day at dinner time for about a month with brakes on the weekends. But I have never been a black coffee drinker, so I continued to have coffee with cream and sugar-free vanilla.

I would argue that I saw zero results. I’m sure that the answer has something to do with triggering insulin but it’s still confusing to me how that small amount of food can make fasting all day moot.

maybe this belongs in show me the science but I figured the folks in this area would have some of that information on their back burner. Thanks in advance!


(Allie) #2

https://idmprogram.com/difference-calorie-restriction-fasting-fasting-27/


#3

Thanks! Yes, I read Dr. Fung’s book and the concepts outlined in this article I understand. I just wanted a little more nuanced discussion as I’m not really referring to caloric restriction in the same sense as what they are discussing here.

They are discussing caloric restriction in the sense of limiting total daily calories, CICO, classic dieting with ~30% total calorie reduction . I’m referring to consuming +/-1tbs of heavy cream 2-3x throughout the day (plus some fake sugar which I know has potential insulin implications).

So I know that the main point of the issue is the frequency of consumption, but it just confuses me still that the amount in question can have such dramatic implications. I get that it is happening, I just want to better understand why. How can eating a tbs of cream 3x a day come even close to the impact of eating a small meal of 300 calories.

I think what the article is saying is that yes insulin is dose dependent- so the small meal triggers more insulin than the cream, but that other hormonal factors are at play when Zero calories are consumed that are completely turned off even when 1tbs of cream is eaten?

It just doesn’t make sense to me, Dr. Fung’s analogy to prehistoric man needing these hormones to trigger energy to go out and get food would make me think that evolution is screwy if he finds one acorn to chew on and loses all of that biological advantage.


(Janelle) #4

I don’t know the answer but my doc wanted to check an insulin level last week at my 8:30am appointment. He asked if I was fasted. I said I’d had a cup of coffee with cream at 5:30. Nope no good. Could have an effect.


(Bacon is a many-splendoured thing) #5

From the link Allie posted:

Over four days of continuous fasting, basal metabolism does not drop. Instead, it increased by 12%. Neither did exercise capacity, as measured by the VO2, decrease, but is instead maintained. In another study, twenty-two days of alternate daily fasting also does not result in any decrease in RMR. . . .
. . . What is the difference? Obesity is a hormonal, not a caloric imbalance. . . . The reduction of insulin and insulin resistance in intermittent fasting plays a key role.

There’s the answer you are looking for, I believe: The reduction in insulin resistance from the lowered insulin and the consequent opportunities given to the mitochondria to heal, especially when fasting is coupled with exercise, as it would have been for our ancestors “in the wild.”

The fat in the cream you mention triggers very little insulin response, but it does trigger some. A minimal quantity of insulin in the blood is required for survival, after all.

The effect of coffee is up for debate. I have read on this forum authoritative statements that (a) coffee stimulates ketogenesis, and that (b) coffee halts ketogenesis. I don’t know why either should be true, and I also don’t know why it is always stated in terms of “coffee” and not “caffeine,” and why tea is never mentioned. Presumably caffeine has no effect, and it is some other ingredient of the coffee bean that is the problem.

I would raise a question about your statement that you saw “zero results.” What precisely do you mean, here? If you are saying that the needle of your scale failed to move, that is one thing, but if you say your dexa scans before and after your fasting days failed to show recomposition of your body mass, that is quite another. It is always worth bearing in mind that we often speak of losing “weight” when we are really talking about losing fat. It doesn’t seem productive to me to get the scale needle to move at the price of reducing muscle weight and bone density. I suspect that the concept of “weight” loss and the idea of “a calorie is a calorie” have combined to lead many a woman into muscle weakness and osteoporosis, clearly a detrimental position to be in as one ages.

Lastly, I would also ask about what might have changed in your metabolic markers from fasting. Many people adopt a ketogenic diet for “weight” loss, but the loss in body fat is secondary to the metabolic healing that takes place. After all, the obesity is a consequence of the metabolic disorder in the first place.


#6

You make some good points! I may be looking in the wrong place for the depth of understanding I want. I’m guessing I really will have to follow @richard 's footsteps to get a biochemistry degree before I’ll be satisfied. I’m an engineer, so I have this annoying need to understand the why’s.


#7

I guess maybe my question is:

I feel led to believe that it’s an on/off benefit; zero calories consumed to get the benefits or consume any amount of calories and the benefits are turned off.

I understand that the issue is insulin related. I guess I’m looking for more information regarding if my above understanding is true or if it’s dose dependant, or if there is a threshold above which the benefits are then turned off.


(Robert C) #8

Fasting has several benefits that go away at different calorie levels.

Autophagy seems to be the one where you want 0 calories - similar to the on/off benefit.
This isn’t known for sure but I have heard Dr. Fung mention it is highly nutrient sensitive (which is why they recommend no bone broth / no calories for people fasting for cancer).

Weight loss - a little bone broth or cream in coffee to help compliance probably isn’t going to affect weight loss.

Metabolic slowdown - this is the tricky one. How many calories do you need each day for you body to say “hey, there’s no food around here, let’s focus on getting some” vs. “this lower amount of food seems livable - I’ll slow calorie expenditure and try to live on this”. To avoid slowdown, you want to be so low that you get the fasting adaptations - muscle sparing HGH goes up, heightened vigilance etc.

I have wondered about this for a while and I think it could get calculated as something like some multiple of your lean body mass in calories or something. Even if someone did calculate it, I think you should still try for as close as compliance allows to zero calories. Eating near that calculated value could be really bad - maybe you get the worst of both - metabolic slowdown and little HGH.


#9

This was really super helpful thank you


(Bacon is a many-splendoured thing) #10

Oh, you poor thing! Yet another one of us to fall down the rabbit hole! But if you can manage to get that biochemistry degree, it would be a mitzvah—we so badly need researchers who know what they are doing, and who can explain stuff to the rest of us.

I’d follow in your and Richard’s footsteps, but then I’d need to take statistics . . . (violent shudder). :grimacing:


(Bacon is a many-splendoured thing) #11

My understanding is it’s a threshold condition. People seem to be able to take bone broth for their electrolytes without trouble, and lean folk who have trouble fasting otherwise seem to derive benefit from a bullet-proof coffee. Such cases make me think “threshold.” But I suspect that (a) the threshold, whatever it is, would be idiosyncratic, and (b) the person’s level of insulin-resistance would be a factor.

Remember the corporate executive, written up in a paper some sixty years ago, who lost weight on a low-carb, high-fat diet but would start to gain weight again after a single apple. I suspect we would consider him highly insulin-resistant, if we could go back in time and test him.