Does a higher body fat impair muscle growth?
written by Philip Stefanov | APRIL 11, 2023
A common belief in fitness communities is that carrying more body fat impairs muscle growth.
The idea is that, beyond a certain point, the body becomes more likely to accumulate more fat than muscle, even if trainees follow best bulking practices––moderate surplus, high enough protein intake, regular weight training, etc.
But is that true? Let’s talk about it.
Where Does The Idea Come From?
It all relates to the body’s P-ratio and how body fat percentage might influence it. The P-ratio simply refers to the amount of lean tissue we gain or lose per unit of weight change.
For instance, someone mainly gaining muscle during a bulk has a high P-ratio and is one lucky son of a gun. However, a high P-ratio during weight loss is not ideal because it indicates that more of the weight loss comes from muscle than fat.
Put simply, as a lifter, you would want to have a high P-ratio while bulking and a low one while cutting.
People are under the impression that a higher body fat percentage affects the P-ratio, with one potential explanation being that it contributes to insulin resistance. Another reason is high body fat increases systemic inflammation, impairing muscle protein synthesis and hypertrophy.
Therefore, a standard recommendation is to get relatively lean before doing a bulk. Doing so would supposedly result in more lean gains and less fat accumulation.
Higher Body Fat Percentage = Suboptimal Hypertrophy?
TL;DR - There doesn’t seem to be a direct correlation between high body fat and poor muscle-building. If anything, a higher body fat might be more beneficial, but more on that in a moment.
As discussed above, one idea is that insulin resistance impairs muscle protein synthesis. The thinking is that muscle cells become less receptive to insulin, which causes more of the nutrients we consume to be sent to fat tissue instead, leading to greater fat gain.
First, research doesn’t find that to be the case. If anything, data suggests that resistance exercise stimulates muscle protein synthesis similarly in lean and obese individuals (1).
Second, even if that were the case (and it’s doubtful that it is), fat cells are also susceptible to insulin resistance. It’s not as if insulin resistance means muscle tissue becomes virtually non-responsive to the hormone, whereas fat becomes more sensitive.
Systemic inflammation is the second potential ‘inhibitor’ of muscle hypertrophy for people with a higher body fat percentage. Fortunately, arguments in this area also fall flat simply because the connections people make to push the idea forward don’t hold any water.
Most of the arguments people make revolve around things like systemic inflammation being bad for hypertrophy, with their data coming from rodent research.
While that is one form of data we could consider when forming an argument, it’s worth noting that we are not mice and cannot take findings and run with them as if they come from systematic reviews of human trials.
What Does That Mean For You?
It means that you probably shouldn’t worry if you’re at the ‘ideal’ body fat percentage to go on a bulk. Additionally, getting as lean as possible before bulking might be counterproductive because, aside from not supporting lean gains, doing so could predispose you to rapid fat regain (2).
One reason is that you would feel hungrier after a long fat-loss phase, making it difficult to maintain a slight calorie surplus. Instead, you might overeat or binge a lot, gain a bunch of body fat, and then become less food obsessed and better able to gain weight slowly.
If anything, we could make an argument that being at a higher body fat percentage is better for lean gains because your body might not feel the need to store as much energy in the form of fat tissue.
Of course, none of that suggests you should go on a perma-bulk. I’m simply saying that you maybe shouldn’t worry that much about your body fat percentage. Instead, you should stay within a healthy range where you feel good, perform well at the gym, and aren’t food-obsessed.
Thank you for taking the time. Until next week,
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