Metabolic Flexibility?


My wife and I decided that this past weekend, we would eat anything that we wanted. She craves things like pizza and pasta. For me, it’s sweets like cheesecake and real ice cream.

I’ve been doing clean keto for well over a year and was wondering what type of an effect a carb binge like this would have. I decided to keep to IF, and not eat breakfast. I didn’t feel like it.

Hiding details in case anyone is fasting

Lunch - Detroit style deep dish pizza & Godiva Cheesecake from Cheesecake Factory
Dinner - Italian, shared entrees of: penna a la vodka, faralle with shrimp, lasagne & Red Velvet Cheesecake

I had a chest & shoulder workout almost 3 hours after lunch. I did a little better on my lifts then I did the previous session. Not sure if it was the added glycogen or I just got better.

I didn’t feel like crap, as I thought that I would have. Slightly bloated, but I also ate past satiety.

When my wife asked me what I wanted on Sunday, I would have been happy with steak and eggs, no cravings for anything I wouldn’t normally eat on keto… but we have one more day of debauchery left.

She wanted some milk, so I did a quick shopping trip, but also bought mini Hagen Das caramel ice cream sticks and funny enough, I craved an apple. I ate the apple when I got home and had an ice cream while waiting for my wife to finish what she was doing before having lunch.

Lunch - Detroit Style pizza, another mini Haggen Daz, shared a Godiva cheesecake
Went for a walk with my wife and bought a Starbucks venti chocolate thingy w/whip cream.
Dinner - Detroit style pizza AND Dominos Brooklyn Style pizza slices & Red Velvet cheesecake

I ate the last Haggen Daz ice cream about an hour later.

Monday morning, I was about 10 lbs heavier then before the binge.

Fasted all day Monday. No cravings, no real hunger.

It’s Tuesday, didn’t feel like having lunch, and might have dinner later… so 48 hour fast.

I just weighted myself and I lost the 10 lbs that I gained over the weekend. I feel energetic, and my stomach isn’t bothering me in the least.

I guess this is what they call Metabolic Flexibility? Since I was able go from ketones, to carbs, to fasting, without skipping a beat. Energy levels are great, and I feel alert and able to function normally.

For me, this is good information to know, so when the world gets back to normal, and I start travelling again, I know that I can eat something non-keto if I’m with customers or business colleagues and not pay any consequences.

Gained a lot from one cheat meal!
(Bob M) #2

It is, although if you saw your blood sugar, it wouldn’t be pretty. Since you haven’t eaten carbs in a while, you’re get a higher blood sugar than if you were a normal carb eater (but with “normal” blood sugar control).

(Michael - When reality fails to meet expectations, the problem is not reality.) #3

It’s what some folks call metabolic flexibility. I think it’s not. We had this discussion here:

My understanding of so-called ‘metabolic flexibility’ is this. When glucose levels are low, especially over time, most cells will switch to using fatty acids and/or ketones for fuel. Ketones allow cells to be metabolically flexible. Eating carbohydrates not so much. Since gluconeogenesis synthesizes all the glucose we need for those cells and organs that can’t utilize fatty acids and/or ketones there is zero need to eat carbohydrates, which are simply sugar molecules of various descriptions.

When glucose levels are low, especially over time, most cells will switch to using ketone bodies for fuel. Ketones allow cells to be metabolically flexible, so to speak. Even the brain and nerve cells, which are heavily dependent on glucose can utilize ketone bodies for fuel. This ability of most normal cells to use ketones when glucose is unavailable indicates that their cellular mitochondria are healthy and functioning properly.

In addition, ketones have some unique properties which make them a “cleaner” fuel for your cells to use. Burning fat for fuel causes less oxidative damage (think “free radicals”) to the cell, and actually makes it possible for the cell to create much more energy than it can from glucose.


No doubt about that. My body isn’t use to THAT much carb in such a short period.

I would imagine that with 48 hours of fasting that I’m now back to normal. I don’t have blood glucose monitoring equipment to check for sure. Just going based on how I’m currently feeling.


I’m more than half way through that thread (very long) but that article that you posted is new to me. I’ll review. Thank you.

(Vic) #6

Staying Keto while traveling on business is super easy. No need to eat any significant amound of carbs at all.
I travel a lot, even staying carnivore is easy after a few trips.
Food is not a liquid, you can take your own on a plane if you want :wink:


If eating at a restaurant, you’re totally right.

I tend to be part of full day workshops where we cater breakfast and lunch. Breakfast being muffins, fruit, sweetened yogurt. Lunch is usually sandwiches and wraps with the odd pizza thrown in.

I usually skip both and drink a lot of tea and any nuts that I happen to bring with me.

(Michael - When reality fails to meet expectations, the problem is not reality.) #8

@Mavro Yes, being fed typical catered carbs is tough. But…

Although, you can’t control the type of food being offered, you can control how much of it you eat. You don’t have to eat any of it if you choose not to. I don’t mean a day long fast, although for a one or two-day workshop that’s doable. What I mean is eat before and eat afterwards and eat minimally at the workshop. Keep it simple. Get up early and eat a keto breakfast. Buy some of those small creamer cups, during the day drink lots of coffee and add lots of cream. Carry a mix of hydrolized collagen and whey powder in a pill jar to get protein into your coffee. Bring a block of cheddar to munch on during the day. Most cheddars have a pretty good ratio of fat/protein. After the workshop adjourns for the day, eat a keto dinner.

(Bob M) #9

I don’t think eating carbs is that much of a big deal, assuming you’re the type of person who can switch back to low carb with no issues. If you’re one of those people who come here 6 months later, saying “I was out of control for months!”, it’s better to avoid the carbs.

For those high carb meals, those are more difficult. Personally, I’d skip breakfast (“I haven’t eaten breakfast in years”; which is 100% true), and for lunch, I’d eat the meat/pizza toppings and toss the bread (“I have a reaction to gluten”; which is also true).

But there have been plenty of times when I’ve had high carb meals or been on vacation and eaten higher carb. Over time, this has lessened a lot (I would go a week eating high carb; now, I limit to meals instead). Also, if I’m going to eat high carb, I’d rather eat something good than crap. Say, real cheesecake (I like mine plain) or good pizza (not marginal/bad) or a nice meal for my anniversary at a highfalutin restaurant. Or ice cream at a good ice cream place, instead of crap at a bad one.

And, like you, I can go from high carb to being in ketosis again very quickly (or maybe not even get out of ketosis).

Now, is this “metabolic flexibility”? I don’t know, but in many ways, don’t care either. Low carb/keto has been my life for 7+ years, and I’ll die being low carb/keto. I may have minor excursions out of low carb during that time, but I’ll get back on the wagon shortly thereafter.

(Vic) #10

I feel ya, at times it sucks.

I’m traveling right now, out of necessity I’m carrying 10 boiled eggs and 2lbs of meatballs.
The airports are still like zombie towns, dead and closed. No restorants open, all lounges closed.
4 flights for the next 12h instead of 4 a minute. Pfff.

A good vacuum sealing machine is wonderfull, if you can afford one.


I do similar things when travelling, eggs, meat, I often add some cheese too even if I eat little cheese at home… They are quite useful.

It’s not always easy to eat keto when travelling. I mean the mental part. I totally want to try things on holiday - but it still must be low-carb. Just not necessarily keto.

Coming back to keto is super easy for me (actually, my only option as it’s impossible for me to stay on moderate-carb. low-carb can go a bit longer but I always end up doing carni days again, pretty soon) but it still doesn’t mean eating a ton of carbs is a good idea. I don’t want to feel/be worse for a single day either. (I have carby days but they are mostly mistakes I don’t regret and my body handles well enough but mistakes nonetheless.)

Do people eat that way? I would have starved in my high-carb times with a menu like this! High-carb never suited me, fine but it seems to be the best for my SO and he wouldn’t like eating like this either. Breakfast would be fine (because cake is the perfect meal for him, it’s not true for everyone…) but some proper protein sources would be needed at lunch… Most sandwiches aren’t that substantial though it’s a possibility.
I got somewhat choosy and it’s a bit surreal to me how others eat…
Fasting sounds good to me in this situation if I don’t have enough fatty protein on me. I probably would eat only in the evening but it’s individual, I can’t eat a little and not being hungry soon.

Now that I think back of my hiking times… Yep. Bread with lard and onions (classic hiking food), bread with jam, sugary tea, ice-cream… Very odd choice from my viewpoint. It’s even worse than the muffin and sandwiches as the protein content was almost zero so it couldn’t last for more than 1 hour in my case. But it was tasty homemade stuff except the (white. I hate white) bread. That’s something.
A proper organized hiking gives hot goulash afterwards :slight_smile: But it was a free one (well we donated some little money but it wasn’t mandatory).


Yeah, it’s tougher. I could get away with munching on some nuts, that I’d bring with me. I couldn’t get away with much else since we all eat together with customers as a group (hauling a block of cheese wouldn’t look good :slight_smile:)

I do IF, and the last time I ate breakfast was last decade :slight_smile: (I love saying that). Nov 2019, in Ottawa before a workshop. I knew I wouldn’t be able to eat some I had a good keto breakfast.

If the workshop ended early, my lunch would consist of the insides of sandwiches that were left over and any salad, assuming that it wasn’t pasta salad.

But if I was really hungry and needed to eat, it’s good to know with my little ‘experiment’ above that I will still feel ok and have mental clarity. I’m not looking to gorge on sandwiches, but it’s good to have options.


I hear ya. I wasn’t sure how I’d feel. I’ve been a carb addict for so long before going keto. Knowing that I can switch back and forth easily, without a loss of energy or mental clarity is awesome. I know that I couldn’t have done that a year ago.

Right now I have zero cravings for anything non-keto which I consider a win. Even while cheating, I would have preferred a steak to the pasta that my wife wanted.

I don’t intend on going off keto, because I know that the weight will come back, the mental fogginess will return, and we already have awesomely delicious food choices as is. KCKO!


Good advice. My wife ordered one and it just came in. I never thought of using it the way that you do (bringing cooked items on a trip), so that opens up a lot of options. Thanks!


Sandwiches, wraps, pizza, and muffins are very cheap in comparison to a real meal. I can count on one hand how many workshops started with bacon/eggs on the menu.

You’re right, the sandwiches are NOT substantial enough. It’s usually two slices of a meat with huge slices of break and maybe some lettuce and mayo.


I know it’s cheaper but still…
To me, carby food is more expensive and many people do eat more of that and that affects the cost but I know not everyone is like that. Amazing that they can get satiated for many hours with mostly carbs. The energy is there so maybe I am the oddball…

It probably works for too many people, it’s traditional enough etc. It would be possible to find some better, cheaper options. There are very cheap plant protein options, for example (they work better for me due to their protein content) but yeah, that’s not as easy as making sandwiches, less people would like that and variety has more cost…

At least the mayo and the other fats may help a bit. I still would need my generous amount of protein for satiation but it’s still better than very nearly only carbs.