Study of 10 day "fast" plus low intensity exercise - no strength loss in men

(Bob M) #1

From Dr. Fung’s Twitter feed.

Oddly, 200-250 calories per day, of basically carbs + whatever is in vegetable broth. Not sure why they did this. Tons of figures. One of the conclusions:

(bulkbiker) #2

More like enforced starvation than fasting.
Sounds a little like Valter Longo’s vegan “fast” that isn’t… honey and fruit juice… hmmm

(Bob M) #3

I wonder if they had to do that to get it approved for funding? It’s like a PSMF – you can get that approved with no issues, but tell people you’re going to have people actually fast every other day, you’re likely not going to get that approved. That’s deadly! :wink:

I don’t know if I’ve ever seen an alternate day fasting study that wasn’t actually low calorie every other day. This one, for instance, which was low calorie every other day:

I guess I’m wrong, as this one actually did request fasting:

But you really have to read the study, as nearly all of them provide calories on the “fast” day.


I personally wouldn’t be directing my Twitter followers to this study, if I were Jason Fung. I can almost hear Layne Norton wetting his pants with laughter at this one. Very odd protocol, especially the enema every other day. It makes little sense to me and I fail to find much I can take from this study.

In relation to alternate day fasting studies, there are a few decent ones where subjects did not eat or consume energy dense liquids (otherwise known as proper fasting studies). The one I have cited below is such an example. There are a few quirky findings here. For example, resting metabolic rate (RMR) dropped by only 83 kcals after 22 days on this protocol. I know Jason Fung is always banging on about this being the advantage of total fasting versus continuous energy restriction (although Layne Norton has correctly pointed out Fung frequently confuses RMR with TEE).

Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism | The American Journal of Clinical Nutrition | Oxford Academic (


He’s not exactly the most respected MD in his field.

(Bob M) #6

@Jamesbrawn007 I’m not pointing anyone to anywhere. I’m not a huge fan of Layne. Sorry. For instance, this is one of the articles on his website:

Considering that I have been eating keto for 9 years now and have plenty of energy for exercise, I can’t see where eating high carb is good.

The study you linked to is not a bad one, and I’ve read it before.

But what everyone says is that fasting = muscle loss. But very few studies actually test strength.

Let’s assume you do DEXA scans, and let’s assume that these are 100% accurate. If you fast for X days, and you “lose” fat-free mass, what does that mean?

It’s unclear. That’s where testing strength comes in. If you lose FFM (fat-free mass), but keep your strength, that’s an indication that you did not lose muscle of the type that’s important.

I see people comparing DEXA scans and saying they “lost muscle”, when (1) that could be true but meaningless, and/or (2) they didn’t necessarily lose strength.

Let’s say you go on a fasting regimen where you lose 50 or 100 pounds. Will you lose FFM? Maybe, as a lot of the muscle you needed to move that 50-100 pounds is gone.

But is that meaningful? If you did not lose or gained strength in whatever exercises you were doing, then no.

Everything is complex, and any number – no matter what it is – has to be interpreted with that in mind.

As far as I’ve seen, this is one of the only studies – the only one I know of anyway – where they actually measured strength.

From that perspective, it’s useful.


10 days and low intensity, what does that prove? Also says they had a 12% reduction in BMR, screw that! Like most studies, that’s not what people are doing in real life, they’re doing what they’re doing much longer term and that’s when everything goes to hell.


I mentioned Layne Norton for the benefit of folks who know he and Fung have a bit of an ongoing fued!

As for the LBM loss during fasting, I don’t think this is disputed. It’s one of the reasons Phinney doesn’t endorse it.

Now is it possible to go through a phase of fasting where you lose fat but not LBM? I would say possibly at best. As mentioned, I personally used ADF carnivore style last Spring and got into excellent condition. And, for that reason, I will go back to that after the holidays to attempt to undo the damage, so to speak.

Going back to the original study, I think it’s novel in design but poor in method. The strength test, for example, tells us nothing as to whether LBM was retained.

Honestly, if I was trying to convince someone to try fasting I would hide this study. I don’t know what Fung was doing flagging it up. :roll_eyes:

(bulkbiker) #9

Too many Monster energy drinks maybe?

(A fool and his bacon are soon parted) #10

We know that the body uses and excretes a certain irreducible amount of nitrogen every day, which must be replaced, or we eventually sicken. Gluconeogenesis to support certain cells is one of the processes that cause us to lose nitrogen; the need for nitric oxide to regulate blood pressure is another.

The observed skeletal muscle loss during fasting is a result of this daily need for nitrogen. Fat and carbohydrate are composed only of carbon, hydrogen, and oxygen, so our stores of glycogen and fatty acids are of no use here; it is only amino acids that contain nitrogen. The body deaminates them, uses the liberated nitrogen, and metabolises the resulting carbohydrate or fat (some amino acids are “glucogenic,” some are “lipogenic,” and some are both).

Given that the body is unable to store amino acids in the same quantity as it can store glucose or fatty acids, the labile pool of amino acids gets used up rather quickly, and the nitrogen must then come from elsewhere. If the amino acids come from proteins that have been damaged, or that have reached the end of their useful life, we call this autophagy, and we like it. When the amino acids have to come from healthy muscle, we don’t like that so much.

Now, the nitrogen-loss studies show a large degree of individual variance, which, I suspect, is at least part of the reason that some people can fast and enjoy it, while others simply cannot.

The ancients understood that forty days was about the longest someone could fast without starving to death (forty is also a significant number in some religions), and they built up to fasting that long over a period of many years. Of course, no one was measuring their muscles, but my guess would be that the long period of training by doing shorter fasts probably helped their bodies adapt. Modern-day hunger strikers become quite weak at a much earlier point.

For some reason, the figure sixty days has stuck in my mind as the point by which by which everyone has died from lack of food, at least according to one study. (Given that there is no ethical way to test this, I am guessing that they probably took the data from Nazi records during World War II, and the like.)


Excellent post Paul.

The world record for fasting is 382 days, although the subject was technically ingesting energy in the form of supplementation as well as, the odd splash of milk in his tea. If you have enough fat mass, you can probably fast for such lengthy periods. Heavier subjects have also had to build up considerably more weight bearing mass, which could then be liberated during the starvation.

(A fool and his bacon are soon parted) #12

Angus Barbieri conducted his fast under strict medical supervision, and he did take vitamin supplements. From the case report:

Patient A.B. aged 27 years, weighed on admission 456 lb (207 kg). During the 382 days of his fast, vitamin supplements were given daily as ‘Multivite’ (BDH), vitamin C and yeast for the first 10 months and as ‘Paladac’ (Parke Davis), for the last 3 months. Non-caloric fluids were allowed ad libitum. From Day 93 to Day 162 only, he was given potassium supplements (two effervescent potassium tablets BPC supplying 13 mEq daily) and from Day 345 to Day 355 only he was given sodium supplements (2 5 g sodium chloride daily). No other drug treatment was given.

There is no mention whether his nitrogen loss was ever recorded. Presumably, in going from 456 lbs. to 180 lbs. (82 kg), he could afford to dispense with a fair amount of skeletal muscle, having so much less fat to haul around.

The authors also mention the following:

There have been reports of five fatalities coinciding with the treatment of obesity by total starvation (Cubberley, Polster & Schulman, 1965; Spencer, 1968; Garnett et al., 1969; Runcie & Thomson, 1970). One was attributed to lactic acidosis during the refeeding period following a 3 week fast (Cubberley et al., 1965). Two were considered to be due to ventricular failure, occurring during the fast, at 3 and 8 weeks respectively in patients who had shown evidence of heart failure before beginning the fast (Spencer, 1968). One patient (Runcie & Thomson, 1970) died on the thirteenth day of his fast from small bowel obstruction. Only one of the five ‘fasting’ deaths has been associated with a fast of more than 200 days’ duration. It occurred during the refeeding period after a fast of 210 days in an apparently well young woman (Garnett et al., 1969). Following this particular report doubt has been cast on the safety of the treatment of obesity by total fasting (Garnett et al., 1969; Rooth & Carlstrom, 1970). However, the allopurinol which had been given may have had unfavourable effects on nucleotide metabolism (Stewart & Fleming, 1969).

It should be noted that deaths from refeeding are the result of an imbalance of potassium and can usually be prevented, if the doctors are aware of the risk and take proper precautions to manage potassium.