Extended Fasting safe? Fung vs Phinney

(Splotchy) #1

Fung and Phinney - both of whom whose advice and experience I greatly respect - have different views on extended fasting. Fung is an advocate and believes several day fasting will not deplete essential protein stores including those in heart and brain. However Phinney disagrees, citing evidence here: https://blog.virtahealth.com/science-of-intermittent-fasting/

It seems extended fasting ‘works’ as in weight loss and often improved hba1/lipid profile. But is this at expense of reducing muscle and REE? Even if temporary this could be harmful.

I have wondered if Phinney’s evidence (some is from years-old data) is based on non-fat-adapted and/or highly stressed subjects, eg Minnesota data and thus might not be extrapolated to voluntary controlled Keto-adapted fasters? But Phinney’s reasoning in link above is persuasive.

I’d be grateful if anyone who can point me to answers! I wondered if @Richard had asked the great man himself at their recent meeting? Hopefully before long there will be more research on fasting/autophagy and more will be clear…

(Bob M) #2

I remember reading some of those studies that Phinney cited and did not think thee were that relevant. I’d review them now, but unfortunately, my internet is acting up. If the address is in the US, it’s not letting me in.

I personally believe in fasting. It’s done the most for me, far more than keto/low carb. I was low carb/keto eating 5+ meals a day, and fasting added a whole new layer. I think one can overdo fasting (I did, did too much, started getting cold every time I fasted), but I think overall its affects are better than keto/low carb.

(Doug) #3

Phinney usually is more focused on a younger, more metabolically healthy, non-obese population. That’s one significant difference, versus Fung.

“Depleting essential protein stores” - the body really doesn’t store much protein, at all - not like it can do with fat or with carbohydrates (converted to fat). Sure, it can burn protein structures, if it has to, to gain energy to sustain life, but this is far down the timeline of what happens when we eat less or stop eating.

“Losing lean mass” can mean the effects of autophagy - using up harmful things in the body, faulty, damaged, old cellular components, etc. It can be getting rid of excess skin - and our skin is ~1/6 of our body weight, often. It can be less water in muscle tissue, as measured by a scan - while in reality it’s not muscle that’s actually been lost.

I’ve seen Phinney say some things about fasting that are demonstrably not true, and which effectively say, “There’s no such thing as autophagy.” That said, he’s due enormous credit for the truths which he has brought to light, and for which he’s lobbied long and hard - often in the face of daunting resistance.

The concept of “losing” stuff we need in our heart and brain is nonsense, at least in my opinion. At one time (and sadly I cannot find what I was reading, now) there was a Russian study on people who had starved all the way to death. The heart lost 3% mass, on average. Not that big a deal - from all I know - and dehydration and fat loss could more than account for it.

Witness the long fasts that many have done - lots of them around a month or more in length, up to the well-known one of Angus Barbieri, who went from 456 lbs/207 kg to 180 lbs/82 kg during a fast of 382 days. It’s not like his heart, brain, or other organs suffered, and he was essentially just fine (and maintained a healthy weight for years thereafter). While I do not know, I’d bet he lost a little muscle in there somewhere - assuming he could move, moving two and a half times one’s weight around likely would result in some muscular adaptation. Even if so, I’ve never seen anything to indicate he regretted losing the weight.

#4

Megan Ramos did an excellent job of explaining the difference of opinion at Low Carb Houston - well worth a watch.

#5

Comparing Phinney to Fung is like comparing a sports analyst to a coach. Phinney has gained his knowledge of fasting from studing it. Fung has gained his knowledge from guiding real patients. Fung as a practicing physician, is responsible for the outcomes of his patients. With his license on the line, he has successfully fasted hundreds (if not thousands) of patients. That said, Fung’s patient’s are sick. Dr Phinney has experience with folks who are younger, healthy and more athletic. If you fit that profile, it may be worth giving a bit of consideration to Phinney’s concerns. But even then, I’d give much more weight to Fung’s work.

(Bob M) #6

Don’t get me wrong,I think Phinney is awesome and continues to produce great results especially for athletes and low carb. For those of us who are metabolically damaged, though, fasting is better. I can show you five+ years of blood pressure data, and my blood pressure benefitted the most from fasting. (That is, adding fasting to low carb.)

(Justin Jordan) #7

Phinney is pretty provably wrong about the muscle mass losses. Just on this forum alone, if we were actually losing that much muscle, you would know.

And you WOULD - a dedicated lifter might add twenty or thirty pounds of actual muscle over a lifetime (more weight is possible, but we’re talking pure muscle) and will triple or more their strength. Losing pounds of muscle will result in strength loss you won’t miss.

He’s biased, so he’s looking for results that support him.

(Matthew) #8

I don’t understand this statement. My understanding is there are two things which are critical to successful fasting. Your diet and exercise. So how can the fasting itself be more important than the diet? So if you were fasting and only ate hamburgers, french fries and coke between fasts, you would consider this fast to be more beneficial than just following a Keto low carb diet without fasting. Is that what you think?

(Dan Dan) #9

…and the answer is Yes …for me anyway :stuck_out_tongue_winking_eye:

When I have an indulgence meal/day fasting will get me back into ketosis within 24hrs without fasting it takes up to 72hrs.

I know that’s not what you meant but it’s what you wrote :wink:

They both are important by themselves but when used together Miracles happen :grinning:

(Jenny) #10

Fung himself says fasting is a great idea after a celebration where you indulged, or just slipped and ate something to put your carbs higher than you intended.

(Running from stupidity) #11

How is exercise critical to fasting?

(Terence Dean) #12

That’s exactly what needs to be done. More research on fasting BUT it costs a lot of money to do it. I’m sure if studies proved that extended fasting was “safe” he’d endorse it. I think he’s erring on the side of caution. Clearly, extended fasting works for a lot of people so all factors need to be weighed against potential risks if any.

I’m an intermittent faster, I don’t eat after 6:00pm until 9:00am the next day (15 hours IF), that suits me because I don’t need to worry about re-feeding issues, and its relatively easy to do.

(Splotchy) #13

I think there is something in the remark that Fung tends to see a metabolically-deranged subset of people - much like many on this forum. Meanwhile Phinney researches all humans. I read Fung started advocating fasting, not because of any strong evidence, but a mix of his hypothesis it would work and his struggle to get people to actually understand how many supposedly ‘healthy’ foods contain carbs.

I hypothesise there is much we don’t know, and while LCHF is almost certainly beneficial to all, I wish I understood more about the physiology of extended fasting, particularly safety and autophagy.

To blindly extended fast does have some risks which are easily avoided if one knows how to mitigate them (ie salt depletion, refeeding, hypoglycaemia if on diabetic treatment) - the thought of just one fatality lawsuit could be enough to make a clinician steer clear of promoting it.

However, if one is alert to the above, I read nothing but success. In my n=1 experience, a week after a 3 day fast I’d lost 2kg of fat and 0.2kg lean mass. I just wish I knew for sure that small non-fat loss was loose skin, tags, debris and not cardiac muscle!

#14

You can not out run a bad diet but you maybe able to out fast a bad diet. The lchf diet will make the fasting so much easier. And there are most definitely some things in a high carb diet that are just bad for you and should not be eaten even if they did not make you store fat.

#16

My experience has been similar to @Dan_Dan. If I fast a sufficient amount of time, it doesn’t matter what I eat. Like @Alley said, I’m not condoning a junk diet, only speaking to the effectiveness of fasting. In The Complete Guide to Fasting, Dr Fung says a HFLC diet is 75% as effective as fasting.

Insulin resistance is created from prolonged hyperinsulinemia. A LC diet triggers less insulin release but fasting lowers insulin even more. Hence it’s greater effectiveness at addressing metabolic derangement.

(Matthew) #17

Remember, it’s just my understanding…
How is exercise and diet not critical to anything? Like living a healthy life?
Secondly, why do the majority of people fast?
I believe there are two main reasons:

  1. To lose weight (Perhaps they are prediabetes or have diabetes or just overweight)
  2. They are high performance athletes (supplement their advanced workouts with a strict intermittent fasting regime).

So if it is to lose weight, exercise would be highly beneficial during fasting to lose even more weight and maximise the affect of the body burning it’s own fat. Ketosis, ketones, avoid losing muscle mass perhaps?
I initially came across Intermittent fasting as a way to supplement advanced exercise. Early Rhonda Patrick podcasts on Joe Rogan alluded me to this. I went to the doctor and told here I might do intermittent fasting. She dissuaded me because she believed it would only be beneficial for those undertaking high intensity physical training. I don’t agree with her opinion however, I believe it goes without saying that diet and exercise are critical in fasting. Like exercise is critical to living a healthy life so would it be while fasting. Some might argue even more so.

(Todd Allen) #18

I bet the number one reason for fasting is religious practices.

(Matthew) #19

When you eat a junk diet you’re out of ketosis until you get back in. @Dan_Dan above mentioned it might take 72 hours without fasting and 24 hours with fasting.

Ideally fasting should supplement either your diet and/or exercise. Who would enjoy fasting just to get out of having had a bad diet. Isn’t it better to fast on a good diet? It is an extreme measure for most as they need to lose more weight for health reasons or high performance athletes use it to supplement their exercise.

My question is for someone like myself who isn’t prediabetic and has a good BMI, good trigs, little uppish on total cholesterol, undertakes moderate exercise would intermittent fasting be beneficial long term? I am currently on 20-4 fasting program.
I know Dr Peter Attia (ex surgeon and longevity specialist) prefers it just because it makes him feel good and he isn’t dependent on his body dictating to him when he should eat. He can hold out, avoid the junk airline food and keep to his diet.

(bulkbiker) #20

Not me… anyway most of them don’t do it right…eating after dark… wimps!

(Diane) #21

I am suffering from long term, ongoing health issues related to mitochondrial disfunction and which contribute to extreme exercise intolerance. I fast for some of the same reasons I started eating ketogenically: to support mitochondrial function, and for the autophagy to help with mitochondrial repair and genesis.

Any hope for an ability to excercise for fitness might come after I (hopefully) get to the point where I can tolerate normal daily activity.