1

votes

Will Intermittent Fasting Slow Down My Metabolism?

Answered on August 19, 2014
Created November 14, 2012 at 10:59 PM

I'm having trouble finding some concrete evidence on the efffects of IF on metabolism. Will it slow down?

I was under the impression that eating small meals was the best thing to do for fat loss, but now people are fasting all day and eating 1 or 2 meals only?

I'm going to give IF a try, but some clarification on this would help!

32f5749fa6cf7adbeb0b0b031ba82b46

(41747)

on November 15, 2012
at 01:04 AM

I +1'd you. ;) And Community Wiki'd myself because a link isn't an answer.

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:12 AM

But, it's a valiant effort and actually a good answer, so I'll up vote anyway ;)

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:11 AM

Geee. I wonder if you created a troll account to ask this question so that you could link to your website that coincidentally provides an answer to this exact question posted TODAY!

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:06 AM

...but I'll up vote anyway

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:06 AM

HMM...I wonder if you created a troll account to ask this question, and then link to your site, which coincidentally provides an answer to the exact same question?

1edb06ded9ccf098a4517ca4a7a34ebc

(14952)

on November 14, 2012
at 11:46 PM

I went through the all the trouble writing that when I could have just linked to this? What a waste of space.

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6 Answers

3
1edb06ded9ccf098a4517ca4a7a34ebc

on November 14, 2012
at 11:18 PM

Meal Frequency: Eating small meals is effective for weight loss if it helps you eat less food overall. IF is effective for weight loss if it helps you eat less food overall. IF or small meals in a iso-caloric environment won't do anything for weight loss. small meals in an iso-caloric environment may be beneficial for body-recomposition if you also practice nutrient timing...but then again, I guess you could do that with IF too.

Metabolism: Eating food does speed up your metabolism over baseline. Not eating food keeps your metabolism at baseline. Everytime you eat, your body expends energy (elevates metabolism) to digest and utilize that food. Whether you eat one huge meal and digest that food over x number of hours, or you eat and equivalent amount in five small meals, you'll still be digesting food for x hours. So regardless of your meal frequency, your metabolism will still be elevated for an equivalent number of hours.

Eating hypo-calorically for extended periods will slow metabolism below baseline. However, this is NOT hypothyroidism and is NOT a bad thing. This is your body adapting to new and usually temporary homeostasis. It is easily reversible (once you start eating more food again) and is not due to thyroid disruption of any kind. It is certainly not bad, but rather, is a good, normal, and healthy thing (if this didn't happen, we'd die A LOT sooner in the wild). In fact, it can just as easily be viewed as an improvement in metabolism efficiency (as you can now do comparable work on fewer calories), but it is finite, because eventually you'll eat up all your reserves and die.

So, ceterus paribus, if you go on a diet and cut calories, your baseline metabolism will slow down (or become more efficient, in other terminology). However, ceterus paribus is rarely the case. Exercise elevates metabolism too. So if you're going on a diet and also starting to exercise, you can elevate your metabolism that way. Drinking more water elevates metabolism. Caffeine elevates metabolism. Eating fish oil or oleic acid rich oils elevates fat burning at rest compared to eating palm oil. So, there are plenty of things you can do to "keep the fire burning." Also, the metabolism slowing down from calorie restriction (but not from thyroid problems) will not make weight loss impossible. This is a hugely overblown MYTH. Just ask any current or former anorexic.

2
32f5749fa6cf7adbeb0b0b031ba82b46

(41747)

on November 14, 2012
at 11:44 PM

Martin Berkan has a nice page on fasting "myths" with quite a few studies cited. See: http://www.leangains.com/2010/10/top-ten-fasting-myths-debunked.html

1edb06ded9ccf098a4517ca4a7a34ebc

(14952)

on November 14, 2012
at 11:46 PM

I went through the all the trouble writing that when I could have just linked to this? What a waste of space.

32f5749fa6cf7adbeb0b0b031ba82b46

(41747)

on November 15, 2012
at 01:04 AM

I +1'd you. ;) And Community Wiki'd myself because a link isn't an answer.

1
0425dfe4b5f5a87181043a542f4d29f6

on November 15, 2012
at 12:03 AM

Video Answer: Right Here

Answer: Contrary to popular belief, being in a fasted state for short periods of time does not decrease your metabolism.

Why? Energy (calories) over your BMR regulates metabolsim, More muscle = faster metabolism. Food has virtually nothing to do with it. For example, we burn a certain amount of calories everyday, even with a low activity level - This is called your basal metabolic rate. Which is different for people depending on age, height, weight, lean body mass, etc.

Your BMR accounts for the majority of the calories you burn everyday just to continue living, and anything beyond that is as a result of your exercise routine for the most part... Not how many meals you eat.

Bottom Line: Meal frequency does not regulate your metabolism.

Suggestions for those who are new to I.F. - I personally LOVE IF, especially for weight-loss; but it may not be a great option for everybody. I've been getting a lot of questions about uncontrolled binge eating after breaking fast -- if this is you, then perhaps it might not be the best weight-loss plan for your individual needs. For example: If you fast for 20 hours, go way overboard within your 4 hour feeding window, then you'll be hard pressed to notice results. :-)

Hope this helps! -Dean www.DeansDailyDose.com

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:06 AM

...but I'll up vote anyway

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:06 AM

HMM...I wonder if you created a troll account to ask this question, and then link to your site, which coincidentally provides an answer to the exact same question?

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:12 AM

But, it's a valiant effort and actually a good answer, so I'll up vote anyway ;)

3a9d5dde5212ccd34b860bb6ed07bbef

(1782)

on November 15, 2012
at 12:11 AM

Geee. I wonder if you created a troll account to ask this question so that you could link to your website that coincidentally provides an answer to this exact question posted TODAY!

0
Medium avatar

(10611)

on November 15, 2012
at 02:36 PM

No, from the standpoint of commonly accepted population models. Harris Benedict BMR is predicted by sex, weight and age. Nothing in there for thyroid activity, eating pattern, circadian rhythm, macronutrient comp, etc.

That's not to say that other factors might be significant in predicting BMR. It's just that no one has fit them to a large population model.

0
5bc61961126827414874d0af0b4e33cd

on November 14, 2012
at 11:52 PM

I've been doing a warrior-style one feeding window per day for about 6 months. I generally eat between 4PM and 8PM. I've found that this has been good for keeping my energy level up and uniform throughout the day. I keep it very low carb (30 g or less per day) except for a weekly or biweekly cheat day where I let myself enjoy some carbs.

Early on I tinkered with longer fasting stretches, 24-36 hrs. If done once a week that wasn't a problem, but much more frequently than that it really started to slow down the machine. My problem has been inadvertently stressing my system by pushing the fasting too hard. I could probably fast for a week without major hunger as I am pretty fat-adapted now, but my mood would be evil.

With the above routine I have been losing about 1 lb a week without much effort. The weekly/biweekly carb cheat day seems to help my mood and seems to keep the body burning fat, believe it or not. I'm still tweaking but this is pretty close to optimal for me.

I did my weekly weigh in today and found that I just fell below 200 lbs, which I haven't done in many, many years. I lost 36 lbs since June 2012.

0
4b9077bdc5240ddeb48b2125c1bd6265

(158)

on November 14, 2012
at 11:38 PM

My n=1 suggests that fasting 24 hours (broken with 1 biggish paleo meal so not quite 24 hours, I guess) a day 5 to 6 days a week for about 2 months will slow you down to homeostasis at 1 month. (No exercise, 1 to 4 cheats meals over the weekend while still generally fassting over the weekend).

I'm currently playing around with alternate day fasting to bring my weekly calories back up and a bigger 4 to 6 hour refeed 1 day a week.

So not concrete by any stretch but I believe severe calorie restriction through severe fasting won't keep the fire burning super hot for too long without some hacking to keep the body guessing.

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