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# Calorie Restriction Duration and Impact on Metabolism

Created May 20, 2011 at 2:23 PM

I don't completely buy the calories in, calories out mind set but I am debating caloric restriction as a means to help push me out of a plateau that I think may be due to me either eating maintenance calories or slightly excess.

Q: Does anyone know for how long you can invoke daily calorie restriction before your metabolism will start to be impacted negatively?

I used the The Harris-Benedict formula (BMR based on total body weight) & the Katch-McArdle formula (BMR based on lean body weight) to estimate my BMR which is at 1925 using either. I am 5"9, 27years old and weigh ~195lbs estimated 20-22% BF.

Then seeing as I have a desk job I multiple my BMR by 1.2 based on research from forums, cant recall where I got it, I had it saved in ever note so credit to the source if anyone knows..

Activity factor Sedentary = BMR X 1.2 (little or no exercise, desk job)
Lightly active = BMR X 1.375 (light exercise/sports 1-3 days/wk)
Mod. active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)
Very active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)
Extr.Active = BMR X 1.9 (hard daily exercise/sports & physical job or 2 X day training, marathon, football camp, contest, etc.)

So my daily caloric intake should be 1925*1.2 = ~2310 to maintain my current weight. I do play recreational football(soccer) once a week and lift weights twice a week for an hour each time but I would say total caloric expenditure would be <1500 combined for a week. I make this assumption as I use a Polar HRM while working out and my two hour long weight sessions avg out at 600c then I subtract 100 for my BMR of that hour. Soccer is a 50 min game in a rec league but its constant sub ons/off so I would say probably 200-300.

Now I am wondering if I apply a caloric restriction of 10calories per lb of fat mass a day which is 22% of 195 = 430calories (bringing me down to 1881 calories a day) if it will knock me out of my plateau without compromising muscle mass or my metabolism.

I would have to say by just thinking about my daily food consumption im probably eating 2300 daily and when I tried IF I hated having to stuff myself in two meals to get my daily caloric intake in.

Anyways would really appreciate some feedback on what people think about CICO and prolonged effect of caloric restriction on metabolism.

Cheers!

(384)

on July 27, 2012
at 05:42 PM

The HB equation doesn't put into account body fat percentage- if you are very fit (low body fat) it will lowball you, and if you are overfat it will overestimate.

(18701)

on May 22, 2011
at 12:39 AM

Thanks for sharing. <3

(1048)

on May 21, 2011
at 10:02 PM

just to clarify I have been in Ketosis for over 2 months now and not dropped a lb. I am approaching this from a ketosis + calorie restriction :)

(1048)
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(5227)

on May 20, 2011
at 09:14 PM

I'm not educated in medicine, so this is strictly from personal experience with short-term caloric reduction.

While the restricting phase of my eating disorder was the most short-lived portion of it, it was where I lost all of my weight. I was severely restricting, and did so for about three months before I decided that I had better recover. (That segued into Kaz's ED, Version 2.0, wherein the young author became bulimic, but that's a story for another day.) My metabolism did not suffer from a few months' worth of restriction, and when I finally decided that I was mentally ready to recover, I realized that the Harris-Benedict calculation was a load of rubbish. I was still consistently under-eating, based on the target calories that HB gave me, and continued to lose weight.

Now, several years later, I maintain my weight on several hundred more calories a day than HB would advise, especially considering my activity level is zilch at the moment. I imagine you burn far more than you think, as well. If you have no prior history of restriction, I think eating less for an undetermined period of time could potentially trigger weight loss without adverse repercussions, but try not to pick a specific number for caloric consumption based on an arbitrary calculation. I have no faith in the HB formula for accuracy.

Good luck! :)

(And, just to be clear, I do NOT advise an eating disorder for weight loss -- it nearly killed me and absolutely destroyed my digestive system -- nor am I comparing your weight loss to an eating disorder. This is simply my experience with how I lost weight, and how my metabolism rebounded from it. /end random disclaimer)

(18701)

on May 22, 2011
at 12:39 AM

Thanks for sharing. <3

(384)

on July 27, 2012
at 05:42 PM

The HB equation doesn't put into account body fat percentage- if you are very fit (low body fat) it will lowball you, and if you are overfat it will overestimate.

0

(165)

on May 21, 2011
at 01:51 PM

I lost 60 lbs. over a year and a half by cutting 1000 calories off of my daily weight maintenance calories amount (example[not exact]= 200 lbs.= 2000 calories to maintain weight- 1000 calories to cause 2 lbs. weekly loss= 1000 calories daily). However, I would not recommend going under 1200 daily calories, and make sure you are getting your required nutrients.

I went to acaloriecounter.com and read their FAQ page. I realize calorie restriction is frowned upon in the Paleo community, but it really worked for me. Since then I have put on 20 lbs. (purposely) by hitting the weights and adding more calories. My waist hasn't gone up much (about an inch or two), but I've added a lot of muscle mass.

I've said it elsewhere, that the problems I had was that I lost a ton of muscle mass, not what I wanted to do. Now, I care more about leaning out, not actual weight... so I'm trying LeanGains and have gone low carb (50 carbs or less daily) to put me in ketosis.

(1048)

on May 21, 2011
at 10:02 PM

just to clarify I have been in Ketosis for over 2 months now and not dropped a lb. I am approaching this from a ketosis + calorie restriction :)

0

(5773)

on May 20, 2011
at 11:10 PM

When I was preparing for bodybuilding competitions I did a lot of calorie cycling to get me through a plateau. Basically, a few days of very low calorie followed by one day of above mantainance calories (usually 500 calories or so). That usually did the trick and actually help jump start the metabolism again. I don't buy into the calories in, calories out totally either but there are ways to manipulate your metabolism and that is one trick I used and it was effective.