I’m hoping that some of you very smart people can help me, because I am real confused here! There is so much information out there, and some of it appears to be very contradictory, so I’m not really sure what to do…
I want to strengthen my fasting practice to lose weight safely and effectively, without affecting my metabolic rate (adaptive thermogenesis), and also increase my time spent in autophagy for its myriad health benefits.
Dr. Jason Fung shows that ADF fasting doesn’t significantly affect RMR, but I can’t find much more information on the subject.
How many hours must one fast before their metabolism increases, and how much does it increase? I found one study which said fasting for 12 hours increased it slightly, but the effects were greatest at 36 hours. Does anyone have any additional information on this? Would eating OMAD (23 hour fast) increase your metabolism enough to offset the adaptive thermogenesis from eating less calories? Or would you need to do longer fasts (36 hours) a few times a week, or something along those lines? How long is your metabolism increased for?
Also, a lot of these studies mention that subjects are still eating during their fasting windows, such as advising people to consume 500 calories on their ‘fasting days’ while doing ADF. Wouldn’t eating such a restricted amount of calories result in adaptive thermogenesis? Isn’t this counter-intuitive? How many calories do you need to consume for it to be considered “low calorie” enough to trigger this? Where is the line between what the body considers a fast and very low calorie?
I also have to take medication every morning- is the amount of protein in the gelatin capsule enough to stop autophagy? If I continue to fast after taking the medication, will autophagy return quickly after the capsule has been digested? Or does the body have to start all over again?
Sorry this has turned into a wall of text…I just have so many questions! Also I’m just a lay person who doesn’t fully understand all of the big sciencey words and jargon and methodology used in the studies. I just want to lose weight and get healthy and not completely bone my metabolism in the process!
I’ve done calorie deficit plus IF to lose weight. I somewhat binge eat once a week(Saturday). I’ve lost 60 lbs and kept it off for a year. My metabolism is high now. I know that’s not scientific but thought I’d share.
There’s no way to lose weight without “inducing” adaptive thermogenesis because it’s the body’s natural response to weight loss. Evolutionarily speaking, suddenly losing a bunch of weight is not a good thing so your body has a number of hormonal processes (including adaptive thermogenesis) that come into play as you start to bring down your body’s energy expenditure. This is more or less unavoidable
I also think you’re struggling because of how misused the word “metabolism” generally is nowadays (for example by ad companies selling weight loss supplements). Metabolism covers an INCREDIBLY complex system by which your body breaks down what you intake and puts it to use, so you’re missing an enormous amount of complexity by thinking about it simply as “the rate at which my body burns calories.”
I would research scheduled refeeds/diet breaks, which are periods of increased calorie consumption which can help manage these hormonal changes without destroying your weightloss progress. Lyle Mcdonald’s “A guide to flexible dieting” (which you should be able to find free somewhere online) is a good place to start for this. Try to get past his awful, awful style of writing (think highschool PE Teacher’s assistant)
Other than that, I would recommend reading about the various processes involved in metabolism. Yes, there are a lot, but if you take it step at a time it’s much more manageable and will give you a more accurate understanding of what “metabolism” actually is. Research and understand lipolysis and fatty acid storage. Research the fasted state and the hormonal changes that occur when fasted (increases lipolysis and fatty acid metabolism) this is a good place to start.
Fasting either maintains BMR, or raises it. It doesn’t really lower it at all.
3 days, On the third day your Metabolism is about as high as it’ll be.
Caloric restriction diets without fasting are what lowers it. Those are the ones where people cut calories and exercise like crazy to lose weight, and then gain it all back after they finish. They eat something like 1200 calories but should be eating 2000, and after the diet their BMR sits at like 1000 for years.
I would never eat 500 calories to lose weight. All you need to do is fast regularly. Start OMAD eating normalish calories + 2 days of fasting per week, and you’ll lose tons of weight. The beautiful thing about fasting, is most peoples BMR increases. The shorter feeding windows mean you can’t shove as much food into your face, and thus self-regulate more. All 3 of these combined, the BMR increase, The short feeding windows, and the body self-regulating lead up to weight loss, and it also means you don’t need to be as careful about calories and you’ll still lose weight. You obviously should try to limit them a bit, it’ll add up to extra weight loss, but I find I eat what I need for the day and then have no desire for more.
I am terrified of this too because it has been the single reason I have never been able to lose weight. But Dr. Benjamin Birkman has a talk on you tube talking about how Insulin suppresses your metabolism. This does make sense as type 1 diabetics can lose weight without trying due to lack of insulin. So if we are eating in such a way that we lower our insulin and “suppress insulin” it is going to increase our metabolic rate. This now makes me understand why I have never been able to lose weight. My metabolism went down a bit and then, I went off the diet and ate more food – and carbs!