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"Impossible to Gain Fat in Post-Workout Window"?

I have recently read or hear a statement that “it’s literally impossible to gain fat 1 hour after the workout”. I sadly can’t quote accurately, as I don’t remember, where I came across this one - it might have been even somewhere here.

Does it even make any sense from science perspective? Theoretical scenario: one follows OMAD and the meal they eat within one hour post workout is the only meal a day (so only these calories and no other). They eat slightly over mainteance. Won’t they gain fat?

I call huge BS on this, as in the end it’s just calories in - calories out and it’s not possible to spend thousands of calories only on building muscles.

But maybe there’s at least some truth to this? Is gaining fat in post-workout window indeed limited? And maybe not talking thousands, but only some extra calories eaten strictly post workout would in fact allow to eat a bit more while cutting, and still loose fat?

Just a theory - oh, as I am not really gonna test it on myself. I am simply curious on where could such claim come from.

Any fat gained in an hour is going to be measured in milligrams at best. I dare say you won’t gain fat in any one specific hour, but more over the course of many all strung together.

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It’s a loosely functional truth taken to its literal extreme to give it more impact.

In theory Insulin sensitivity is peaked and MPS is significantly raised post workout. Your body will be more effectve at using nutrients consumed for hypertrophy and will use calories preferentially for that as opposed to storing them as fat.

The theory is, then, that PWO calories are much less likely to be stored as fat.

However while fat gain during this specific period may be limited, your body doesnt work in closed systems.

If you put extra calories in post workout, such that you e.g fully replenish glycogen, it just means that any carbs eaten after this ‘magic window’ are more likely to be stored as fat.

Assuming you start at a maintenance base line, after factoring in the workout, those extra calories will mean some weight gain.

Ultimately any statement that absolute will have holes in it though.

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If we are concerned with the literal statement itself

Well you can prove the existence / possibility of something in an n=1.

I daresay if you took someone and had them, post workout, drink 4,000 calories of pure glucose syrup then, assuming they didnt go into hyperglycemic shock, their body would simply not be able to use all of that glucose and at least some would be stored as fat.

Sure, but I don’t assume one binge after workout from time to time. I am talking if someone took the statement literally and following it for extensive period of time ate over mainteance, but only in a window post workout.

If you think it’s not possible, just consider there are thousands of people following OMAD and eating just one meal a day. And it’s not really that hard to hit like 5000 calories in one hour. Every person, who has a history of binge eating, has been there.

I used to go to the gym that was on 3rd floor, while there was a McDonald’s on 1st. You could literally finish your workout and within 10 minutes end up eating Cheeseburgers. Or there are plenty of people simply eating at the gym.

Assume your mainteance, factoring workouts, is 2400 kcal. You eat 3000 kcal, but only immediately after the workout (no other meals at all). And you don’t do it once or twice, but every day for some time. Will you not gain fat?

And please note I am not really talking like drinking 3000 kcal of olive or maple syrup. Rather just eating standard healthy foods, but at caloric surplus. I am trying to think about it somehow reasonably.

Taking the statement litetally, they would gain very little fat in that one hour. Or the next. Or the next. But over time, it adds up.

It’s a very silly statement.

I believe it sums it all up and this exactly, what I was thinking.

Still people making such statements are literall danger to newbies, as someone could actually read it, start attending gym and then keep eating their KFC’s and candies post workout, thinking they won’t end up fat.

A newbie who reads something on the internet, takes it as truth and implements it immediately, with no regard for consequences, is a danger to them self, society and their loss can probably be put down as a success of natural selection.

There are people on the internet claiming that you can cure autism by drinking bleach. Literally.

There are bigger problems than people eating more for 1 hour after they workout.


Thanks to the relatively slow process that is lipogenesis, they will fortunately have ample time to observe the data feedback, being fat gain, that will disprove the false statement this hypothetical newbie have based their training and diet beliefs on. If they pass the natural selection test, they will realise the statement must be false, and will stop before they become irreversibly obese.

bro, what if I finish training at 5, but have my meal at 7

do i fuck myself out of this window?

The window is a silly thing. Don’t get wrapped around it.

That’s going to attract a police presence rather quickly. Instead, try to just eat your food quietly.


And quickly, don’t want to miss the window.

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First of all, there are slow digesting meals (low GI carbs combined with fat, high gluten pasta with sauces) that have been PROVEN to take over 8 hours to be completely absorbed. Even pure, fast digesting protein still results in amino acid and glucose (or insulin) levels being elevated in the blood for 4 hours. Fat intake stimulates liver output of glucose for up to 24 hours (people who eat around 50-60% fat can lower their blood sugar and insulin needs significantly after a 1 day fat elimination.

Second, if training is intense enough, it can actually raise blood sugar due to adrenaline and cortisol release. Heavy weightlifting tends to raise conter-regulatory hormones to keep blood sugar up, and that means that you CAN be hormonally insulin resistant after a very heavy workout. This is one of the reasons why very high stress training (NFL football games, Olympic weightlifting competition) don’t benefit athletes’ physiological development but tend to tear them down. This is why the Russian’s used 90% of competition max as a training max (generally) and never went above 90% of THAT.

(OIW, not all training improves insulin sensitivity in the short period after the workout. Training raises hormones to tell the liver to pump out glucose, and to tell adipose cells to pump out fat for fuel. Muscles have to have glycogen and fatty acids depleted to create room for nutrients, and if the stress hormone response exceeds the space created in muscles by nutrient depletion then there won’t be anywhere to put the food anyway except fat.

I reality, if you are not killing yourself, then you are going to be more insulin sensitive for hours after a good 1 hour training session. Things like feeder workouts-sled dragging, pool work, walking, bike riding moderately-can raise insulin sensitivity and even reduce stress hormones if the stress is kept low enough.