Is a calorie deficit really required on a ketogenic or zero carb diet?

(Liz ) #10

I want to mention that if you spread the 1500 calories over a whole day, eating every two hours say, then you will constantly be spiking your insulin preventing access to body fat, & possibly slowing your metabolism, getting that “starvation effect”.

If you eat your 1500 calories in one (or 2) meal(s) & fast the rest of the time, you allow your insulin to drop so you can burn the extra 500 calories you might need for energy from body fat, & your metabolism stays humming.

So I don’t know for sure how important calories in turns out to be, still figuring that out for myself, it seems to be a bit different for each person, but I know for sure that WHEN you eat however many calories you’re going to have is super important.

#11

Thanks - I understand the spiking of insulin at meal times prevents the body from using its own internal fat stores (so eating in a time restricted window is ideal for accessing body fat) I can’t wrap my head around the point our bodies may start slowing metabolism down due to lowered daily caloric consumption.

Is there a limit to how much fat energy the body can access in a given amount of time? ie; 100 kcal / hour of fat?

Another thought experiment, if one consumes enough protein in 1 meal to handle your lean tissue requirements, there should theoretically be no need to consume any fat (or carbohydrate) as long as your body has sufficient body fat to supply your remaining energy requirements.
ie: John consumed 100g calories of protein (equal to say 1000 kcal of calories for example) to support his lean tissue requirements, and relied on his body fat to supplement his remaining 1000 calories (overall 2000 kcal daily need). Would John be able to pull all 1000kcal from fat or would his metabolism slow down?

Or is there a minimum dietary requirement based on body fat % remaining that you one should keep to ensure your metabolism does not slow down?

The insulin piece and time-restricted eating / IF seems key to allowing the body unhindered access to its ‘virtually unlimited’ energy available in body fat, and I know in water fasting all of your energy requirements are met purely from body fat breakdown, but understand that after ~72 hours you begin to experience modest metabolic rate reductions.

(Liz ) #12

So @richard has a calculator he’s posted re: max amount of calories accessible from burning body fat & it’s finite. Also it’s a percentage, so the more fat you have on your body, the more calories you can access. Which is why thinner folks might feel lousier fasting.

My guess is the minimum number of calories you can consume before you start slowing metabolism is highly individual. But it’s a great question! Thanks for laying out your thoughts, very interesting.

(Richard Hanson) #13

Over the holidays I ate quite a bit more food, all keto, than was my norm. I indulged.

More fat, more keto coffee, more protein, and more good red Wine.

12 more pounds as well,

Calories in / Calories out has an impact, at a minimum for my personal n=1, but energy balance is not the only factor, likely not even the most important variable.

Keto for Life!

Best Regards,
Richard

(jilliangordona) #14

This will almost always happen at first, but if he were to give it more time, his metabolism will rev up and drop the weight that was gained. Bodies do NOT want to gain weight, it just takes some time for the body to realize the surplus is here to stay, and they begin up to rev up making more hair follicles, keeping the body warmer, etc.

#15

Interesting… So a newly “thinned” person with say only 20 lbs of body fat is only be able to supply a fixed # of calories from body fat… Difference would need to be made up by dietary intake or slowing of metabolism.

Earlier in this individual’s weight loss journey they may have had 40lbs of fat mass to pull energy from and fasting alone could have at that time supplied all caloric needs.

Anybody have a link to this calculator? It would help me with how much energy I could pull from my current body fat, and help me decide a maximum caloric deficit so I don’t exceed what my body can provide via body fat burning alone.

This would also demonstrate most weight loss calculators simply using cico (ignoring what your body fat can contribute to your daily energy needs) to achieve a set weight (xx kg) by certain date (8 weeks in future) are setting you up to fail if you actually don’t have enough body fat to lose! ( Ie: there is a threshold where one’s body fat level can’t supply you with the daily energy expenditure and that’s the point cico restriction type dieting will fail if too aggressive.)

(Liz ) #16

Here:

Yep, and calorie calculators that fail to factor in insulin levels affected by meal timing & carbohydrate percentages will always fail.

#17

Liz already posted the link but the short answer is 31 calories per day per pound of excess body fat.

Dr. Jason Fung explains all this very well IntensiveDietaryManagement.com, read the blog from the start.

If your insulin is not low you cannot access stored body fat no matter how much you have, when it is low you can and then assuming you have enough, your body supposedly does not care whether it is coming from stored fat or olive oil

(Rob) #18

Over feeding of fat in metabolically healthy people on Keto seems to echo your results - no weight gain even though they took in an extra 2000kC of fat (butter and olive oil) a day for 3 weeks - so in that experiment your theory on the body’s self regulation of fat usage vs disposal would seem correct.

#19

This is where I believe the info I have on fasting falls short of the complete picture.

Assumption: we have full access to body fat stores all 24 hours of the day thanks to minimal carb intake and insulin at a low point (for many, we likely don’t have full access to body fat but let’s continue assuming we do).

So 2000 kcal required daily. I have 30 lb fat so my body “can” supply 30lb @ 31kcal = 930 kcal.

So, now I fast.
That means my body needs 1170 kcal from diet. If fasting, it gets none of this energy so we would expect metabolic slowdown… Where else can the energy balance be seen unless other energy is being used in addition to fat burn?

Does energy from glycogen stores add to your daily caloric “consumption”?

(Liz ) #20

Jason Fung explains that there is no metabolic slow down while water fasting, in fact the metabolism speeds up. This may have diminishing returns over the course of many days, I see mixed information about that. But there is a complete difference in metabolic reaction between eating some calories and eating no calories.

#21

Yes I read and listen to Jason fung as well. Unfortunately though, to me it seems that the two pieces of information conflict.

If there is a limit to how much fat energy one can mobilise, how can one’s metabolism speed up during a fast? What mechanism other than fat burning is supplying energy to fuel that increase?

(Liz ) #22

I have never heard Fung say HOW metabolism increases during a fast, only that it does. And since I know he is deeply science based, I believe him.

The reasoning they always give is if metabolism slowed on zero food, humans would have died off in the cave man era.

Without having to digest food, we probably don’t actually need as much daily energy either.

Sorry I don’t have the science to explain it. These are all great questions.

#23

Thanks for that, and of course Fung’s clinical experience shows fasting does work. I’m just doing my best to figure out for me what level of caloric deficit will have minimal impact to metabolism. I guess I’ll just need to experiment by having the appropriate amount of protein daily for lean muscle, and then just trying to keep my fat at a level below caloric maintenance. Trying 15% for now and that 15% should basically come from my dietary fat intake.

I’ve done 3 extended fasts total. My 3 day and 5 day ‘kept me going’ and I continued downward trajectory of weight loss (but I did have ‘more to lose’ at those times) and most recently my 7 day (most recent) I did gain back all the weight I lost and then added some additional back on. So I wonder if I did some slowing down to my metabolism during that 7 day fast. I guess it’s all about experimentation, maybe that level of prolonged fasting isn’t for me.

I decided at the end of that weight regain to just ‘reset’ and not do any prolonged fasts for some time, just try to really monitor macros closely and I did found I was likely going over 20g / day and probably overdoing it on calories as well. So I’ve been logging everything in to MFP to keep honest.

Question for any MFP users (or just general caloric trackers), when you exercise and you get ‘credit’ for the workout in calories (woohoo 300 more!) do you allow yourself to consume the additional food that day or do you try to ignore that ‘bonus’ and keep going with normal intake?

(Ethan) #24

Technically, a calorie deficit is required to lose weight–unless you are hacking off limbs or surgically removing parts of your body.

What is questionable is the way that you create the calorie deficit. A calorie deficit can be created by eating MORE calories than you did before, as long as you also increase your burn rate. If you decrease calorie intake too much, you may lower your BMR, which could actually reduce or eliminate the deficit you tried to create.

(Adam Kirby) #25

This concept has been disputed though. The numbers come from some Ancel Keys study conducted on carb eaters if I’m not mistaken. Unfortunately it’s all we have to go on.

#26

Stumbled upon this older thread:

Sounds like a fat-supplemented fast could prevent metabolic slowdown. I will definitely try one of those for my next extended fast this year to see if the dietary fat intake can balance out what I should theoretically be able to burn from my own stores.

The symptoms described by @devhammer with the cold are what I experienced on my recent 7 day fast. Devhammer did you since attempt this fat-fast? Anything you’d like to add since this post, any experiences to share for those trying to overcome the final crunch, where the advice that got us here while carrying a higher BF% isn’t quite getting us the rest of the way? Some caloric restriction seems like the only answer, but how much is the big question.

(Liz ) #27

Since Keto is an ad libitum diet where you are supposed to eat to satiety, assuming your satiety signals work properly, I think getting hung up on calories is a dead end, tbh. We are not closed thermodynamic systems. What and when we eat seems way more important than how much.

Just anecdotally I had 1,200 calories one day, carbs at 20g, protein around 60, fat filled in the rest. The next day I had the same carb/protein macros but filled in with dietary fat up to 1,900 calories. Nothing happened on the scale. And I will keep mixing it up as Megan Ramos suggests. Falling into a predictable eating pattern can get you into a weight loss rut.

At this point in my Keto journey which started March of 2017, I’ve lost 40 pounds with about 20 or 30 left to go (female, 5’8”, 48 yrs old). I’ve been bouncing around the same scale weight since November but my clothes fit differently. I’m not exercising yet.

I’m Keto 100% of the time, I believe I’ve now healed my fat cells & they are working super efficiently, hanging on to their stores & keeping me stalled. From what I understand fat loss ability ALL depends on basal insulin level. And the only way to push your basal insulin level down after basically the six months any diet works, is fasting. How long you fast for effectiveness is highly individual and you will have to experiment as you said you will be.

As far as the exercise calories calculated on MFP I’ve always read they are wildly over stated, I ignore them. The most important thing about exercise re: Keto weight loss as far as I can tell is the increased mitochondria for fat burning. You cannot possibly burn enough calories exercising to make a weight loss difference. But you can make your body better at burning fat for fuel.

(G. Andrew Duthie) #28

I don’t think that caloric restriction is the answer at all. That being said, I can’t claim to have found a magic bullet for “the final crunch” either. I have done some additional fasting, with fat supplementation, and the supplementation does seem to help with making the fast manageable. I’ve gone as long as 6 days, but I found that trying 2 cycles of 6 days back-to-back, with a feast day in between, did not work well for me. I think the next step for me may be trying some intermittent fasting, but the other important variable in my case is sleep consistency (or lack thereof). It’s pretty rare for me to get a full 8 hours of sleep or more, and occasionally I get less than 6, which is arguably a major contributor to keeping my insulin high, and preventing the remaining fat from going.

At the end of the day, I’ve seen enough convincing evidence that caloric restriction leads to metabolic slowdown that I do not plan to go down that road. Is it possible that CR would work for someone else? Maybe. But for me, I don’t think the number of calories I’m consuming is the issue, and I know that restricting has potential downsides that I wish to avoid.

(Chris Holmes) #29

This is a good thread, and perhaps I missed the message somewhere, but if there are any biochem folks out there who can help me understand why a body in full ketosis would still need a calorie deficit to lose fat. I get that restricting carb intake will lead to lower caloric consumption, but I thought the science behind keto, was that the metabolic changes your body goes through on keto, causes burning of fat stores for energy, which makes me wonder whether the weight loss is actually due to burning fat, vs just consuming less calories than your TDEE. It would be interesting to see a study that compares people in ketosis eating enough calories to match their TDEE vs people who are not in ketosis eating a 20% deficit to their TDEE.