Nope, they do gain weight, or avoid gaining weight by counting calories [0]
> Your body adjusts its metabolism based on the amount of food you eat as long as it's not chronic.
Suggests that your metabolism is changing, as though your body becomes more or less efficient at burning calories because you're eating more or less. Instead, these guys eat a huge surplus of calories and then go into a deficit to get back to their standard weight.
I'm not exactly sure what their bodies are doing, but I guarantee you my body would get rid of that food extremely quickly before it was fully digested.
Objectively, I don't think this is accurate.
Most people who are overweight got that way slowly.
Dr Mike[1]'s theory is that modern processed food is to blame - not because it's unhealthy, but because it's too tasty. Companies that make food are in an evolutionary arms race with other companies to get consumers to choose their products. And one of the best ways to do that is to make the food as tasty as possible.
Another things many companies probably try to optimize their food for is low satiety[2]. That way consumers consume, and therefore buy, more of their products.
---
1. From Renaissance Periodization
https://www.ers.usda.gov/amber-waves/2020/november/average-s...
https://www.theatlantic.com/business/archive/2012/04/how-ame...
I also think this is true related to food. Your body adjusts its metabolism based on the amount of food you eat as long as it's not chronic. That's why you can have competitive eaters that can eat a weeks worth of food and not be overweight. Spikiness and variability are probably good for you. Its funny that the Bryan Johnson types who closely control every calorie in their body have such a bad reaction to any variability. I don't know if its him, but I heard someone not be able to sleep and their levels got all messed up from one sweet. And their conclusion was sweets are so bad for you, rather than you're building your body to be too fragile to shocks.
The interesting thing is when this breaks down. Obviously if you eat a weeks worth of food every day for a sustained period of time, you will start to gain weight. Or if you run 12 miles every day, you will be in such a deficit that it won't be possible to lower your metabolism enough. Outside of the extremes, I think it's a cliff, where you have to have some kind of shock for some period of time for your body to react.