I have a pair of bathroom scales in my studio that I do not use the normal way. I ask clients to stand with one foot on each scale, then I watch the two numbers. Most people assume they are standing evenly. Most people are wrong.
When the split between left and right creeps past about 3kg, I get curious. Not alarmed, curious. Because in my experience, a scale imbalance is rarely just a scale imbalance. It is usually the visible end of a much longer story that started somewhere else in the body, sometimes years earlier.
A few months ago, I stood on my own scales. The split was not 3kg. It was somewhere between 6kg and 10kg, all sitting on my left side. That number sent me looking backwards through my own body, and what I found links three things that do not look related at first glance, a set of bathroom scales, a sore foot, and the way your brain decides what should hurt.
Where it actually started
My sciatica did not begin in my lower back or my hip. It began at my right big toe.
I have a bunion on my right foot. As the big toe drifts inward, it loses some of its job as a stable base to push off from. Your body does not tolerate instability quietly. Somewhere else has to pick up the slack, and in my case that was the muscle and tissue around my right hip, which gradually stiffened to create the stability my foot could no longer offer on its own.
For a while, that trade worked. Then it stopped working. The stiffened tissue around my right hip eventually became a source of pain in its own right, so without really deciding to, I started favouring my left side. I know this because I checked the tread on my running and walking shoes, and the left side was noticeably more worn than the right. I had quietly walked and run my way away from the original problem, straight into a new one.
That new one was on the left. More load, more often, for longer. Add in a detail I had not connected until recently, that I had not barbell squatted in over a year, and my glutes on that side had grown weaker than they should be. Weak glutes do not stop you moving. They just hand the job to smaller, less suited muscles around the hip, and those muscles are not built for the load they were suddenly carrying. That is where my sciatic symptoms began, along with a strange side effect, half numbness across my third, fourth and fifth toes on the left foot.
One foot, one bunion, and a story that ended up in a completely different limb. If that sounds like an unlikely chain of events, it is worth knowing how common the destination actually is.
The numbers behind sciatica
Sciatica is far more common than most people expect. Reviews published in journals including the New England Journal of Medicine and the StatPearls medical reference maintained by the US National Institutes of Health put the lifetime incidence somewhere between 13 and 40 percent, with some estimates going as low as 10 percent and as high as 43 percent depending on how strictly it is defined. Put simply, a meaningful share of adults will experience it at some point in their lives.
It tends to arrive in a particular window. The peak age range is 30 to 50, and it is rare before age 20 unless there has been trauma. Interestingly, the research does not show a clear pattern by sex. Sciatica is not something that favours men or women more strongly, it shows up across both fairly evenly.
Most cases are not permanent. Research summarised in the New England Journal of Medicine and a review in the journal Acta Neurochirurgica found that somewhere between 60 and 80 percent of people see their symptoms ease substantially within 6 to 12 weeks with conservative care, meaning no surgery. That said, a meaningful minority do not follow that timeline, some studies found around 30 percent of people still had some pain a year later, which is exactly why catching the pattern early and understanding what is driving it matters.
None of those numbers explain why my sciatica traces back to a bunion. For that, we need to talk about what pain is actually for.
Why your brain protects you before it explains itself
Here is the part most people skip past. Pain is not a straightforward damage report from your tissues to your brain. Pain is something your brain produces, as a protective response, based on everything it knows about the current level of threat to your body.
This is not a fringe idea. It comes from decades of work by pain scientists including Lorimer Moseley, professor of clinical neurosciences at the University of South Australia, whose research has shaped how pain is taught to health professionals internationally. One of the core concepts in that field is that pain is a protective output, not a direct measurement of tissue damage. Your brain is constantly weighing signals from your body against context, memory and perceived danger, then deciding whether pain is a useful response right now.
That reframes my whole story. My right hip did not stiffen because something there was broken. It stiffened because my brain and body decided that stiffening was the safer option, given the instability coming from my toe. My left side did not start hurting because it was suddenly weak in isolation. It hurt because it had quietly been asked to do the job of two sides for a long time, and the protective system finally raised the alarm.
Where the three threads meet
So here is how the twin scales, the sciatica and the brain protection story actually connect.
The twin scales gave me the data. A 6 to 10kg shift to my left is not something I would have felt day to day, but it is exactly the kind of asymmetry that builds slowly and quietly until the body cannot compensate any further.
The sciatica was not a random back problem. It was the downstream result of a chain that started at my toe, moved to my hip, crossed to the opposite side, and finally landed on muscles that were never designed to carry that load, made worse by a year without the glute strengthening work that barbell squats provide.
The brain protection piece explains why the chain happened at all. Every stage, the stiffening, the favouring, the eventual pain, was a protective decision, not a malfunction. Your body was never betraying you. It was trying to keep you moving safely with the information it had.
I am not fully through this yet, but the sciatica is subsiding and the hip pain and associated symptoms are easing. The work has involved rebuilding the strength I had let slip, particularly through the glutes, addressing the stability issue at the toe rather than just the pain further up the chain, and giving my nervous system reasons to feel that the area is safe again rather than under threat.
What this means for you
If you have ever wondered why a niggle on one side of your body eventually shows up as pain somewhere else entirely, this is usually why. The site of the pain is very often not the site of the original problem.
That is exactly why I use the twin scales with clients before I use anything else. A 3kg or greater difference is not a diagnosis, but it is a prompt to ask a better question, what has this person been quietly compensating for, and for how long.
If your own story sounds anything like mine, a foot issue that never got addressed, an old injury you worked around instead of through, a strength gap that crept in without you noticing, it is worth having someone look at the whole chain rather than just the part that currently hurts.
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