Will eating 1/3 of normal calories throw me out of ketosis?

(Chuck) #21

I follow the OMAD concept most days a week, which means I fast for at least 19 hours per day then I have about 5 hours of eating time per day. I don’t have a lot of weight to lose, but I am losing weight slowly, but what is most amazing is how much my body measurements are decreasing. I went a month with no weight loss but reducing my belly by almost 4 inches. I am not concerned about the scale numbers but I am concerned with reducing my waist, and upper thighs.


Unless it’s dangerous starving. Not a common thing, fortunately, not even on keto but some people have it.
Normally yes, don’t force things. Maybe tweak something. I don’t consider it good to be happy with starving without hunger, I would change my food choices, timing or whatever to get enough food (not like I ever need it, my body demands a lot of food every day. I merely had a few undereating days here and there but that’s fine). I saw people (with eating disorder, especially in the past but some attitude stayed with them) eating the most low-cal but (for them) satiating food items resulting in really serious starvation but no hunger or mood to eat more.

OMAD typically lowers our food intake though I met one who had the opposite…


That’s fine but there are way more healthy experiments to do… One can play with fat/protein ratio, using less food items (my goal since so long… it could help a lot with my fat-loss I am sure but I see other potential or even likely benefits… makes my experiments easier etc.), maybe the timing can be improved… But there are certain things I would never try and some of these aren’t good for anyone. Like very very serious undereating. Pure fasting is better but not for too long.


Not quite. The four largest studies on fasting with the purpose of increasing longevity were mixed. The two studies on mice clearly showed evidence to support fasting for longevity. The scientists were able to increase their lives by approximately 40%. A 3-day mouse fast would be the equivalent of a 14-day human fast. Also, both test subjects were bred for this purpose. Furthermore, once the mice stopped fasting, their body weight increased to much higher levels than when they first started. Not all mouse studies can be replicated in humans.
The two other studies, which were done on primates (closest to humans), showed very mixed results with regard to longevity. They, too, gained more weight. The tests done on primates in today’s world would not currently be approved by governments for ethical reasons.
Might there be a duality in fasting? Short-term good, long-term bad?

(Allie) #25


(Bob M) #26

My thoughts about mouse studies is that they sometimes could be useful for determining mechanisms for things. Even then, we really don’t know how well those mechanisms transfer to humans.

As for limiting calories, what a difficult question. To me, the evidence is clear that if you decrease calories say at a certain level X for a certain length Y, your body will limit the amount of calories it burns. The questions I’ve never seen answered are what are X and Y? And how do they interact?

For instance, can you reduce calories to 500 calories a day for three days or maybe 3 times a week (the inappropriately --in my opinion – named intermittent fasting)? What happens then? At would point in Y length with X calories does your metabolism decrease?

Some people believe that fasting is the same as calorie restriction – it’s only calories, don’t you know?

But I find if I fast 36 hours, something more than just lowered calories happens. It could be biome-related, hormones-related, both, other stuff, not sure. But I find I will eat a normal meal and become overfull. That lasts typically at least through Saturday, if I don’t eat at all on Thursday. If it was solely calories, wouldn’t I be starving and trying to eat more? Not to mention things like sleep can get affected, which to me means something is going on with hormones.

I think if you exercise too much, your body will reduce its energy expenditure. If you reduce calories too much (let’s ignore true fasting > 24 hours), your body reduces energy expenditure.

It’s no longer clear to me how we lose weight given this.

(Bacon is a many-splendoured thing) #27

Whereas Jason Fung says the body reacts very differently to fasting from how it reacts to restricted calories. It makes sense evolutionarily.

Benjamin Bikman says that the state of ketosis and the state of fasting are essentially the same, from the point of view of the bioenergetics involved. The difference is that ketosis allows us to eat.

(Bob M) #28

I wonder about all of this. When we go on a keto diet, many of lose weight relatively quickly I went from 43 pants to 38s then 36s fairly quickly. Now, my original goal of 32 seems impossible (stuck on 34s right now and have been for a long time), but if CICO is meaningful (and I’m not convinced it IS), we reduced calories.

But if we reduced calories, why doesn’t the effect of a lower BMR (basal metabolic rate) show up? I mean, if you go on a high carb, low calorie diet, it does.

I know there is some effect where keto seems to cause a greater loss per day of calories (400?), and certainly that helps, but it does not explain why the body doesn’t figure out fewer calories are coming in and therefore cause a lowered BMR.

This is there the MIMO theory actually makes more sense, as it can help explain this. But even it fails (I think?) when we start discussing hormones. There is definitely something about hormones that affect weight loss, in my opinion, and I even think it’s possible the biome could too – at least to some extent.

Maybe it’s like physics, where I doubt there will ever be a unifying theory that explains both atoms and sub-atomic particles and planets: maybe there is no one theory that explain weight loss (or gain)?


I doubt it necessarily does. I always heard/read and it made sense that a decent deficit doesn’t harm our metabolism, only excessively big ones do (but they do it very quickly).
My SO always lost fat on high-carb (as he can’t eat otherwise) and never experienced anything that could hint at such things, of course, it’s merely N=1. As I always seriously overate on high-carb, I have no experience with it. I don’t get a bonus allowance on keto and eating at a deficit is about just as hard. Not overeating is easier, that’s something, not like it affects my weight much but it’s about health and not being wasteful too.

Lots of things influence fat-loss, I am pretty sure of it. For some of us it’s simpler, for some it’s more complicated.
Many says that they eat more on keto while losing fat so even that part isn’t the same for all of us…

(Chuck) #30

When I was trying to lose weight by restricting calories only,it always worked at first and was a reasonably fast weight lose, then it would stop working and I would start gaining weight on the low calories even lower than when I was losing. Now with keto/low carb I lost weight slowly but have lost inches quickly, where as on low calories weight lose was quick for a short time but the lose of inches around my body was extremely slow at happening. Now with low carbs and fasting between 18 and 23 hours a day I am losing inches quickly and weight slowly at times and then quickly for a short time then back to slimming down without a weight loss. With fasting and low carb I am never hungry, I have lots of energy, my brain is never in a fog, I haven’t had sinus or allergy issues, my joints no long ache. And after my walks/hikes my heart rate recovery is almost instantaneous. And my unmedicated blood pressure is even lower than it was on the medication. And another thing is my skin rashes are gone and at 75 I no longer have the issue with the slightest bump breaking my skin and causing me to bleed.
I never had this results with low calorie high carb diet.

(Bacon is a many-splendoured thing) #31

Dr. Fung says there is a difference between calorie restriction and 0 calories. It sounds reasonable, evolutionarily speaking.

The appetite reduction of eating a low-carb/keto diet comes from lowering insulin, which interferes with the leptin receptors in the ventro-medial hypothalamus, but it is predicated on having extra fat to be shed. And as we shed the extra fat, our appetite increases until–still eating to satiety–we are getting all our calories from our food, because there is no more excess fat to shed (in other words, we are in maintenance mode).

Again, there is a difference between eating to satiety and deliberately restricting intake. Eating to satiety allows the body to determine how much we eat. Deliberately restricting intake dictates intake level to the body. The body takes the restricted intake as a signal of famine, whereas eating to satiety allows appetite to control intake.

Apparently, fasting allows the switch from feeding ourselves from our food intake to feeding ourselves from our reserves. Of course, we can only fast for so long before bad things happen (the hard endpoint being death from starvation, of course).


It makes perfect sense to me, I even feel very, very different. I can’t fast long (over 20-24 hours) since I lowered my carbs very much but it would be still easier than eating little (like, 70-80% of my energy need for more than 1-2 days…). It’s very different. If I eat, my body wants its nutrients and when I fast, it can’t help but to switch to burning its fat reserves though it bothers me for food for a while (but it’s nothing compared to the hunger after too little food). When I stop eating for days, I rapidly feel more and more disconnected from eating while if I eat every day, my body wants its food and not a tease. Seems logical to me.

I never got the appetite reduction (let alone hunger) until carnivore and then I got negative appetite with huge hunger, that was the worst. It’s better now and I can handle it without quitting.
Surely both appetite and hunger is influenced by many things. There are a mental component even for hunger and appetite is probably mostly mental in my case…? It’s the desire, after all though it is loosely correlated with hunger even in my own case and I have among the worst correlations between those two. Or rather there are correlated with my natural eating window…

This appetite (or rather hunger) reduction may apply just fine for a single meal and not for the whole day. I sometimes have the first and almost never the latter. On the (thankfully rare) days when I get satiated quickly, I still need the same amount of food for a day so I must eat many times. Not fun.

(Doug) #33

Bob, configure things so the body is using up some of its stored fat. Not saying it will be easy for everybody, nor that everybody (on the forum or otherwise) will agree on methods. Even if there is general agreement on a thing, it may not fit a given individual.

Good question, and a lot of things affect it. Ancel Keys’ study went 24 weeks with reduced intake, and the Biggest Loser contestants went 30 weeks. There was concrete stuff like reduced thyroid function, so I think we can say that 5 months or more is going to do it. Decrease intake by X amount - not sure how that plays out. If in a given case the body smoothly transitions into burning stored fat to make up any shortfall (like what many people going to ketogenic eating experience), then maybe there’s no significant slowdown in metabolism.

The Biggest Loser people were really beating themselves up with exercise; gotta say that too fed into the results. There are things like the 'Newcastle Diet" where people do ~800 calories per day for 12 weeks (may have been fewer weeks in the past). While I don’t know if their metabolisms were/are checked, or how the subjects fair in the long run with weight re-gain, the program is quite successful overall with respect to diabetes.

Personally, I think that 800 calories per day would be mighty rough; I’d much rather fast. On the shorter end of the time scale, lots of people are fasting 1 to 40 days very successfully now. Big difference from fasting once in a while to reducing intake every day for longer periods of time. Usually big differences, too, based on the amount of fat one has. Keys’ subjects averaged fairly lean beforehand, and they were definitely really lean at the end. :smile:

Some people say they don’t like fasting and/or that fasting did not work well for them - I believe it.


Yes, in the long term, I believe this to be true. In the short term, I think there is a lag period between fewer calories consumed and the metabolism realising this. Once the body realises it is not getting enough fuel, it downregulates. There could be other mechanisms at work that we truly do not know how they work in the body. This may also happen with keto. As the fat satiates, many will start to eat less. I believe this could be one reason why some people lose weight on keto. However, once weight loss has plateaued, then what? Some will eat even less food or move over to OMAD, or carnivore.
Fasting means different things to different people. It depends on which protocol and for what purpose. True fasting means no food and only water, generally speaking. Dr. Fung uses fasting (no food) in his programs because he believes that once glucose has been used up for energy, fat will now be used as a fuel source. Obese patients find it very difficult to burn fat, regardless of their level of activity. Generally, in his programs, he will recommend 2-3 fasts per week (T2D). Intermittent fasting that is done every day kind of defeats its purpose and will downgrade metabolism. I personally do IF (16:8) twice a week. I stopped my longer fasts (1–4 days) because I found that, over the course of 3 years, I was losing muscle mass. As I age, I want to grow or, at the very least, protect my muscles.
What about the idea of “feast or famine?” We all seem to get the famine (fasting) part, but what about the feast? I think there may be an evolutionary argument to be made that we all could feast once in a while. Balance?
Please note that the opinions above are my own based on my research and my experiences.


Why would it do that? It makes no sense to me. Humans don’t evolved eating all the time, many of us can’t do that… Oh well, maybe different people are different at that too. Some are undereating on IF, of course their metabolism is suffered but mere IF? :slight_smile: That allows such a big eating window! It’s quite normal not to have a huge one.

About the slowing metabolism… When I lost fat (way before keto), I automatically had higher-cal days now and then (I have those even without losing). I can imagine it helped with my metabolism. I needed the deficit for fat-loss but I had days with surplus. But my SO loses fat on high-carb with deficit (and lots of hunger) every day and it works for him (not pleasant but his metabolism stays fine). But he always quickly slims down (using a decent but not huge deficit), that probably matters a lot.
It must be quite individual. I suppose some of us has a more stubborn metabolism than others. Our body responds to a deficit differently (and it matters how big it is, of course, compared to our reserves).
But we can’t even know our energy need, only can notice bigger, longer changes…


For simplicity’s sake, let’s say at rest you burn 2000 calories per day normally. If you restrict calories every day (IF) to 1500 calories per day, you have created a deficit. Your body will initially burn 2000 calories and you will lose weight. There is a lag time. After the body realizes it’s only getting 1500 calories, it adjusts to this new level and weight loss plateaus.

The opposite is also true.


Yeah, you state this. I am very sure it’s not true for everyone as many of us never experience this.
Many people simply slims down with such a deficit, no problem.
It’s possible some people are different.

I talked about IF in general, not IF with deficit but rereading your previous comment, you might mean IF with deficit only. But both seems a pretty good idea to me, for the people who it suits, of course. (How else could I ever lose fat? :smiley: It obviously must be IF with a deficit and sure I am not alone. Though I personally have my high-cal days too. Not everyone needs them.)

(Bacon is a many-splendoured thing) #38

Beware of thinking that you know which is cause and which is effect. Gary Taubes likes to point out that teenagers don’t grow because they eat more, they have to eat more because their hormones are making them grow. It may very well be that, in ketosis, we eat less because we are in weight-loss mode, if we have excess fat to shed.

Dr. Phinney says that his data and clinical experience both show that as people on a well-formulated ketogenic diet continue to eat to satiety, their food intake spontaneously rises until their excess fat is gone (or what their body considers excess, at any rate) and they are meeting all their energy needs from food intake. The problem comes when a person would like to lose more fat, and his or her body objects.

Also, as Jason Fung likes to point out, for all that we talk about “weight” as a one-compartment problem, it is actually a two-compartment problem. This is why people have been known to simultaneously add muscle while shedding fat.