Let’s get something straight from the off: yes, your genetics can absolutely influence how easily you build muscle, how stubborn your fat loss is, and even how your body responds to training and diet. But before you cancel your gym membership and blame mum and dad for your lack of bicep veins, let’s give this all some context.
Science has made it pretty clear that genetic variability plays a role in our body composition. Certain people are just predisposed to build muscle more easily. They may have a higher ratio of fast-twitch muscle fibres, respond more favourably to resistance training, or possess naturally higher testosterone levels. Same goes for fat loss. Your metabolism, appetite regulation, and even where your body stores fat are all genetically influenced.
The key word here though is influenced. Do some people seem to build muscle from just looking at a set of dumbbells? Sure. Do others struggle to control their portions without feeling like they’re starving. Unfortunately, yes. This is all partially down to genetics. But is it a life sentence? Absolutely not.
Genetics Influence Your Physique – But Don’t Define It
Numerous twin studies have shown that while genetics can account for somewhere between 40-70% of your body’s response to training, that still leaves a massive chunk down to the choices you make: how hard you train, how mindfully you eat, and how consistently you do both.
You might not have been dealt the best hand, but it’s how you play it that really matters. You can’t control your genes, but you can change your habits. An old mentor of mine was fond of saying ‘genetics may load the gun, but your lifestyle pulls the trigger’.
There’s a narrative in gyms that just won’t disappear – that if you’re not getting bigger or leaner, it’s just down to ‘bad genetics’. While it’s true that some people need to work harder to see results, ‘hard gainers’ aren’t cursed – in my experience they’re often just under-eating, under-recovering, or under-training. Labelling yourself as having ‘bad genetics’ can too easily become a self-fulfilling prophecy if you let it dampen your efforts.
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Muscle gain isn’t magic. It requires progressive overload, enough protein, quality sleep and time. Lots of time. If you’re training hard but haven’t gained significant muscle in eight weeks, that’s not genetics – that’s impatience. Try eight months. Try eight years. This is a lifelong pursuit (and one that literally makes your life longer). Checking out because of slow progress is a surefire way to guarantee no progress.
Why Most ‘Bad Genetics’ Are Really Lifestyle Problems
Likewise, fat loss can be frustratingly non-linear, especially if your body is particularly fond of its reserves. But again, the basic principles hold: calorie deficit + time = fat loss. Some people may need to work harder to stay in that deficit – fighting stronger hunger cues, or finding that some areas of body fat take longer to shift than others – but the formula doesn’t change. No matter your DNA, you have to trust the process.
Genetics can also influence how muscle growth looks on you. Different frames and statures are going to give way to noticeable muscle-gains at different rates. Five kilos of upper-body muscle will look very different on a 6’4” frame than on a 5’9” one (a rare win for us short kings). As well as this, there’s variance in the actual shape of our muscles that’s mostly predetermined. Shorter muscles that don’t spread as far across the limbs will look fuller and more rounded as they grow, whereas longer muscle bellies may require more total growth to really pop, visually. Some people have great tricep potential, but terrible calf genes – and we all know someone with legs like tree trunks who has never set foot in the gym. I tend to think of this like blowing up a balloon: the shape may be predetermined, but if you want it inflated, you’ve just got to keep blowing.
Are there outliers for whom their inheritance makes a significance difference? Of course. There are rare edge cases where genetics play a much larger role. Conditions like myostatin-related muscle hypertrophy – where muscle growth is significantly enhanced, to a dangerous degree – are real, but incredibly uncommon. On the other side of the spectrum, some genetic disorders or hormone imbalances (thyroid issues, low testosterone, insulin resistance) can make fat loss or muscle gain far more difficult.
If you genuinely feel like you’re doing everything right, and nothing’s working, then maybe it’s worth speaking to a doctor, getting bloodwork done, and ruling out any underlying issues. Knowing about them might change your approach, and although the principles of muscle gain and fat loss will still stand – it might put your mind at ease. But, for most of us, the issue isn’t ancestral sabotage – it’s inconsistency, information overload, or trying to chase too many goals at once.
So yes, genetics matter. But probably not as much as you think. For me, the more productive question is: what am I going to do with the genes I’ve got?
