I'm sure you have heard this a million times in bodybuilding articles and forums:
Only beginner weightlifters can gain muscle and lose fat at the same time.
For intermediate and advanced weightlifters, they can only cut or bulk, but never both at the same time.
Only beginner weightlifters can gain muscle and lose fat at the same time." For intermediate and advanced weightlifters, they can only cut or bulk, but never both at the same time.
You can do whatever you want... you won't necessarily be successful with it, or you may not see optimal results, but that doesn't mean there is only One True Approach and nothing else can work.
To build muscle, your body needs a caloric surplus to give it energy. In contrast, to lose fat your body needs a caloric deficit so it will convert fat into energy. Losing fat and gaining muscle, therefore, appear to be opposing goals. Therefore, a beginner losing fat and gaining muscle would be a paradox.
Well, first off it should be noted that there are not very many studies done on this, so you should challenge the expectation that a beginner can lose fat while gaining muscle. Perhaps their measurements were not methodical and accurate, or were obscured by outside variables? Maybe they had a base amount of muscle that was hidden by fat, and losing fat only made it appear like they were gaining muscle?
Assuming that the paradox is true, you must revisit your assumptions as they were either incorrect, incomplete, or both. The first assumption that is made is the time period in which the caloric deficit/surplus occurs must be a day. A 24 hour period is a convenient unit of measure for counting caloric intake, but perhaps not for our body. It is possible that with a healthy and well-timed post-workout meal your body is able to build muscle while still running at a caloric deficit to lose fat.
Another assumption that must be challenged is that both outcomes have to be positive at the end of the day. Well that is not the case because we aren't interested in losing fat and gaining muscle for one day, but rather for the long term (say, over the course of one month). So even though you may have gain 0.4g of muscle and gained 0.2g of fat on one day, the next you may lose 0.1g of muscle and lose 0.3g of fat. So while neither day saw the "paradox" of both gaining muscle and losing fat occurring at the same time, the long-term effect was a net positive in both directions.
Why does this biological process shut off after the beginner phase?
In your beginner phase you have the most explosive growth, both in lifts and in muscle; however this is not a linear growth, as there is a definite upper limit in which your growth tapers off as you come closer to your genetic potential. This brings us back to what I was saying earlier about the "optimal" approach. As a beginner you have such explosive growth that you get away with the less-than-optimal, but as an advanced lifter you are so close to your upper limit that you have to finely tune your program, meaning you have to go through the bulking and cutting cycles.
Anyone can build muscle/lose fat over time, it's called recomping. It's just that this is a very fast process for beginners, and significantly slows down for more intermediate/advanced athletes.
Firstly, it's not a biological process that only fires up when you're a beginner and then shuts off at some arbitrary point. Muscle building and fat burning happens along a continuum. Your body is continuously breaking down fat and building up new muscle at all times (and also storing new fat, and breaking down muscle). All training/recovery does is induce signals that adjust the rate of each of these processes.
Think of them as a continual, random biological processes.
Of course, the optimal conditions for muscle growth include a caloric surplus. Similarly, the optimal conditions for fat loss include a caloric deficit. But all this ("optimal") does in reality is make the signals to do either process stronger. But you can still perform both muscle building and fat loss even if it's not optimal.
When you're a beginner (you don't have much muscle/you have significant fat) these equations are more favourable (for muscle growth and fat loss). As you get more advanced (approach your muscle limit) these equations reduce in magnitude of effect and you can no longer to any meaningful degree (compared to what could be achieved through dedicated cut/bulk cycles) do both at the same time.
Everything is faster as a beginner. Your body reacts to a stimulus very rapidly the first time it experiences it. However the reaction slows down every time the stimulus is repeated. Your body actually works to ensure the response is lesser over time. Sucks but that's life.
The important bit is that this happens over a continuum and you don't suddenly switch from beginner to nonbeginner all of a sudden.
For marketing reasons, it's beneficial to sell consumers this idea of a "magical" beginner phase that you have to take advantage of or you will lose it. Some well known programs in fact work on this premise, twisting expectations with half-truths so that an uninformed consumer would begin to think that they have to train a certain perfect way as a beginner or they lose a huge opportunity. Of course such programs/diets/coaches will then offer you their expertise to tell you exactly how you should be training. This normally involves some sort of payment/book purchase/etc.
The reality is there is no magical beginner phase, and you can't waste it. The closer you are to your genetic potential the slower progress is, the further away from it you are the faster progress is. Training is simple, ignore the hype.
Because of how fast (or slow) it produces gains. After a certain point of advancement, even though you are still building muscle/losing fat, the rate at which it happens is just slow. In such situations people wanting maximum progress switch to bulk/cut cycles because they can overall make gains faster like that.
You can try to achieve multiple contradicting goals and do each of them to a mediocre level, or you can focus on one goal at a time and master it.
