24 hr fasting increases Metabolism đź‘Ť

(Manuel De Leon) #1

This will definitly confuse the opposition, but, Fasting for 24 hrs increases metabolism :+1::+1:

(Ron) #2

I knew there was a reason I chose that schedule to follow!
Thanks for the validation:boom::sparkler::fireworks::bomb::boom:

(Robert C) #3

Shouldn’t the title be “24 hr fasting increases Metabolism in mice”? I am not a scientist but 24 mice hours might be different from 24 human hours. Not sure of the connection with the 5:2 diet either. Isn’t that the diet where people - on the 2 days per week - simply calorie restrict at around 500 for women and 600 for men? Not trying to be a purest here - I consider 30 calories of bone broth still a fasting day. But, an entire meal is a “fasting day”? Hmmm…

(Doug) #4

Robert, it surely is a lot different. People can usually fast many days in a row without it being any really big, life-threatening deal. A mouse will usually be dead after 3 days or so.

However, for people that have fat reserves above where their body really thinks, “Holy Crap, Starvation!” - it does appear that fasting increases metabolism. Dr. Fung says, “Four consecutive days of fasting increases basal metabolism by 13%.” With alternate daily fasting, even over many cycles, metabolism is maintained - Dr. Fung again: "22 days of ADF. Even with weight steadily decreasing, the resting metabolic rate is statistically identical at the end of 22 days. "

His thesis is that the lowered insulin levels brought on by the fasting results in the body being able to more easily access stored fat for energy. In the presence of higher available energy, the body revs itself up some.

(Robert C) #5

If Dr. Fung is saying that after 22 days of alternate day fasting (so 11 24-hour fasts) your metabolism is the same - then he is saying for humans - 24 hour fasting is not increasing metabolism. I guess you are saying Dr. Fung might not agree?

(Doug) #6

Robert, not sure there - for all I know, the metabolism might increase during the earlier 24 hour fasts, then revert to the previous “normal” by the end of that series. That the metablic rate is maintained, even while an average 4% weight loss was recorded, is significant. Here’s Fung’s post on it:

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

One basis for the metabolism increasing while fasting is the body secreting more of the hormone norepinephrine. The following study found that resting energy expenditure went up 14% (surprises me, there) during the first day of an 84 hour fast.

EDIT: Ugh, I just read it wrong. The 14% increase in metabolism was not during the first day, but was the difference between the first and third days. Sorry about that. :confused:

(Manuel De Leon) #7

Yes, I saw that too. To be exact the research was done on mice. How significant that difference is—i don’t know, I happen to be Apprentice Instructor (civillian) for the Air Force. I too don’t consider the use of 500 calories during a fast as a legitmate fast. I believe the proponents look at the insulin response garnered from the 500 calories as inconsequential. Now, I’m not sure if in the bigger picture of such a difference matters or not. Like you, its a personal preference for me.

(Ron) #8

Don’t care to jump into this debate but for the record my 2 day fasts are alternate 42hr complete fasts with bone broth coffee and water consumption only as I disagree with the 500 calorie limit as being legitmate fasting also. Carry On.:zipper_mouth_face:

(Allie) #9

I’m not a mouse.

(Brian) #10

For the short term stuff, I do, too. If I’m going to fast, I’m going to fast and not eat anything. I will drink water when I’m fasting. And when I eat, I eat well.

Maybe if I were doing multi-day fasts that pushed out past maybe 2 or 3 days, I might think more towards at least electrolytes. But for just a 24 or 36 hour fast, I’ll just have water, thank you.

(Actually, I’m about 20 hours since I ate and am in the process of digging the last of a garden patch today. And it’s not easy digging. I’ve had water. I’ll probably have supper tonight. No biggie at all.)

(Allie) #11

Dr Fung and Megan Ramos have discussed the 500 calorie idea of fasting and they also disagree with it. They say on days that you’re fasting, fast, and on days that you’re feasting, feast, but don’t claim to be fasting when you’re actually calorie restricting.

(Doug) #12

I think this makes a lot of sense in general, as the hormonal changes that occur when fasting are not the same as when restricting calories. I don’t know when a reduced metabolism really shows up during calorie restriction, but it surely does by 24 weeks, as with the Minnesota Starvation Experiment, and the 6 months that the “Biggest Loser” contestants did.

From what I’ve seen today - in the course of reading this whole thread - participants in one study averaged a 14% higher resting energy expenditure on day 3 of an 84 hour fast, versus on day 1. Sure would be nice to have some trials with longer-term results.

(Lori Erickson) #13

It makes sense to me that our bodies would go into survival mode short term…It seems like I’ve read this in Dr. Fung’s book, but I don’t know where to find it. If you’re a cave human and you don’t have any food (fasting) you would need the extra energy to get out and hunt something. This is no time to be all lethargic, laying around on the bear rug with a low metabolism.