Fung says fasting doesn’t slow metabolism – Comparing apples to nothing

As anyone that has every read anything I’ve posted likely knows, I think fasting is stupid and Fung is a flake. He has the right idea about insulin lowering and weight loss but has this fasting thing totally blown out of proportion. The problem is that he sounds credible and people hoping for a miracle will jump into the fasting pool hoping to swim but will only end up drowning. Here is an example of how anyone can make anything sound logical if they don’t compare apples to apples.

This is the article I will reference.

https://idmprogram.com/fix-broken-metabolism/

In this article Fung claims that fasting not only doesn’t slow metabolism but speeds it up! Wait, what? This is where you have to use a tiny bit of common sense.

If metabolism speeds up during fasting would Ghandi have survived his many fasts including one for 21 days. If you’ve ever seen Ghandi he didn’t have a bunch of weight to lose.

What would happen if Ghandi’s metabolism where to speed up as Fung suggests? He didn’t have much fat to get him through so he would have quickly died. This just doesn’t hit very high on the old common sense meter does it? We have evolved a brilliant system over the years to deal with a lack of food. It was never intended to be used as a weight loss tool but as a survival mechanism for a harsh environment where food availability was not always a certainty. The metabolism must slow in order to preserve ourselves and if it did not then anyone lean, like most where for almost all of our evolution, would not make it long. This is just the first place where Fung’g logic falls flat. This can be seen easily by measuring the thyroid levels in someone who has fasted for any substancial amount of time. Thyroid is what controls metabolism for the most part and thyroid levels tank when fasting. Here is a measure from Peter Attia when he fasted. Look at the drop in Free T3 during the fast. His metabolism is in the shitter.

Now lets look at his major failure. Comparing data. He starts by talking about the metabolic adaptation of the contestants of the biggest loser in a 6 year follow up.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/oby.21538

This study shows that the caloric restriction and intense exercise caused a dramatic decrease in metabolic rate that persisted for 6 years after the contest ended. Great. He then tries to say that this is because they were calorie restricted and that if they had of fasted they would not have seen this happen. He uses some interesting logic about insulin being high or low to explain it but he does not support this with any actual science. He actually states that after 4 days of fasting the metabolism increases by 13% but conveniently does not site any literature to support this. I did find an article that shows a similar result.

https://sci-hub.tw/10.1093/ajcn/71.6.1511

The explanation of this is pretty much what I would expect. The increase is due to an increase in the adrenal hormone norepinephrine. As this adrenal hormone increased so did metabolic rate. This rise only continued for 4 days and reduced there after despite the continued rise in epinephrine.

“We cannot explain the decline in energy expenditure on day 4 of our study, even though norepinephrine was still rising. Although not studied by us, it has been suggested that energy deprivation has suppressive effects on the hypothalamus-pituitary-thyroid axis that diminish the metabolic rate.”

What do we think would happen if one continued this fast past 4 days? That is right, metabolism would drop. Another important thing to note is that apparently Fung has never heard of adrenal fatigue. This is real and there are millions of people that can attest to that. Chronic fatigue is rampant and the direct cause is adrenal fatigue. What do we think years of forcing massive increases in adrenal hormones is going to result in? Funny enough caloric restriction also results in increased adrenal output. Unfortunately I have not been able to find any studies showing the result of 4 days of caloric restriction on metabolic rate but I would predict you would see similar results as far as energy expenditure and norepinephrine concentration.

He goes on to talk about a study that showed metabolism didn’t drop after 22 days of alternate day fasting. He again fails to site the study because god forbid anyone be able to actually read the study and see if what he is saying is true. I was able to find it though.

https://sci-hub.tw/10.1093/ajcn/81.1.69

Well this is hardly a bolster to his hypothesis. The results showed that after 22 days of alternate day fasting the metabolic rate in fact did drop. From 1594 cals to 1512 cals. While that sounds like very little it is still a drop and this is only after 22 days of alternate day fasting. So only 11 days of fasting. that is 82 calories in 22 days or about a 3.72 calorie a day decrease. The biggest loser study was after 30 weeks of caloric restriction and showed an average drop of 610 cals after 210 days. That is a drop in metabolic rate of 2.9 cals per day……Less than fasting. Imagine that. Lets see a study of alternate day fasters after 210 days. Now that would be interesting wouldn’t it.

Here is the reality of all of this. Fasting is caloric restriction. It is just broken up differently. Essentially the results will be the same long term depending on what the average calories are. The metabolism will slow the same and the weight loss will be the same.

Person A eats 3 meals a day every day and eats 1800 cals a day. Their metabolic rate is 2800 cals per day. That is a 1,000 calorie per day or 7,000 calorie per week deficit. They will likely lose about 2 lbs a week until their metabolism slows. The weight loss will slow as the metabolism slows and will eventually stop.

Person B does alternate day fasting and eats 3600 calories on eating day and no calories on fasting days. Their metabolic rate is 2800 cals. This results in an average caloric intake of 1800 cals per day which is a 1,000 calorie per day deficit or a 7,000 calorie per week deficit. They will likely lose about 2lbs per week until their metabolism slows. The weight loss will slow as the metabolism slows and will eventually stop.

They are exactly the same. They will have the same long term result and this is why all of these long term fasters like Jimmy Moore and Carl Franklin can no longer lose weight.

This study comparing Alternate day fasting (ADF) to straight caloric restriction (CR) shows this directly.

https://onlinelibrary.wiley.com/doi/full/10.1002/oby.21581

“At 8 weeks, ADF achieved a 376 kcal/day greater energy deficit; however, there were no significant between‐group differences in change in weight (mean ± SE; ADF −8.2 ± 0.9 kg, CR −7.1 ± 1.0 kg), body composition, lipids, or Si.”

The only benefit this study might have shown was that in the 24 weeks after the initial 8 weeks the ADF group seemed to gain more lean mass and less fat mass back. The difference was minimal and could be confounded by measurement techniques. The test used only measures fat and not fat so depending on hydration levels this could swing wildly. Water will show up as lean mass making the fat mass % seem larger. Overall weight regain in the followup was again, the same.

So to close, Fung compares apples to nothing. He looks at a 4 day result in metabolic increase from fasting, which was actually related to an increase in adrenal output and not to lowered insulin, and compares it to a 6 year long study of caloric restriction. He also tries to compare a 22 day study on alternate day fasting with a 3.72 calorie per day drop in metabolism to a 210 day diet contest TV show that resulted in a 2.9 calorie per day drop in metabolism. Fung needs a small lesson in statistics here. I fail to see how any of this proves his point.

Remember, friends don’t let friends do stupid things like fasting and listening to people that say fasting is a good idea.

Keto ON Friends,

Coach Jack

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