Achy knees are as emblematic of long-time lifters as cauliflower ears are of long-time Jiu Jitsu practitioners. Lift long enough and hard enough and your knees (and possibly other joints) will start to grind away and maybe get peed out and carried to the ocean where they might eventually become part of some distant tropical reef, home to some plucky invertebrate.
Okay, that's probably not how it works. Regardless, some lifters will be luckier than others. Their joints will degenerate, but only to the point where they'll suffer the occasional grumpy knee, usually caused by a cold front that found Canada too limiting for its ambitions.
But plenty of not-so-lucky lifters will spend years inundating themselves with alleged cartilage-rebuilding supplements like glucosamine and chondritin, eventually graduate to NSAIDS and opioids, and finally relent to a total knee replacement and spend the rest of their lives getting felt up by TSA agents at the airport because they lit up the X-ray scanners.
Researchers at the University of Alabama at Birmingham might have presented people with bad joints an alternative fate, though. They found that simply going on a low-carb diet decreased pain and inflammation in guys with rickety knees.
What They Did
The scientists found 21 old guys with bad knees. They took serum samples and put them on one of three diets for 12 weeks:
- A control diet where they continued to eat as they had been.
- A low-fat diet that consisted of 800 to 1200 calories a day.
- A low-carb diet that allowed them to eat as many total calories as they wanted, but that only contained 20 grams of carbohydrates a day.
Every 3 weeks, the participants were asked questions relating to functional pain, self-reported pain, quality of life, and depression. After the 12-week diet intervention was over, the researchers drew up a last round of serum samples to compare against the pre-test values.
What They Found
The guys on the low-carb diet reported reduced pain intensity and unpleasantness during functional tasks, as well as less general self-reported pain, as compared with the control group and the low-fat group.
They also found significantly lower oxidative stress in the low-carb group. Their blood samples indicated a reduction in the concentration of TBARS (thiobarbituric acid reactive substances), which are a marker of inflammation.
"In only 12 weeks, the quality of life and functional pain of this population were significantly improved, which may have been the result of a reduction in oxidative stress," concluded the team.
What This Means to You
The results of this study might reflect a chicken or the egg dilemma. The researchers figured that the low-carb diet caused a reduction in inflammation, which of course resulted in reduced knee pain.
However, I wonder if they might be looking at the results through a biologic lens rather than an engineering/physics lens. The low-carb group lost a lot of weight, more – perhaps surprisingly – than the low-fat group. That alone could have caused a reduction in inflammation and a reduction in pain.
Consider that every time you take a step, the force on either knee is 1.5 times your body weight. Let's say you weigh 200 pounds. That means when you walk on level ground, you're putting 300 pounds of force on your knees. Hell, if you walk up some stairs, the force is 2 to 3 times your bodyweight, and it's 4 to 5 times your bodyweight when you bend at the knee to pick up your iPhone.
Let's say your Fitbit nags you into taking 10,000 steps a day on level ground. Assuming you weigh that same hypothetical 200 pounds, you're going to put a cumulative force of 3,000,000 pounds (300 pounds force x 10,000 steps) on your knees during that day.
But what if you lost 10 pounds of bodyweight, perhaps through a low-carb diet? That same 10,000 steps would then subject your knees to a total of 2,850,000 pounds, which is a daily reduction of 150,000 pounds of pressure.
Of course you're going to experience less inflammation if you lessen the cumulative load. Of course you're going to experience less pain. Lose more than 10 pounds and you reduce the total load further.
So while the low-carb diet may have reduced inflammation and contributed to the improved quality of life in the gimpy-kneed guys, at least some or possibly a lot of the reduction in inflammation was caused by the reduction in weight. Of course, to joint pain sufferers, the specific reason for any reduction in pain probably doesn't matter as much as the end result.
- Larissa J Strath Catherine D Jones, MSPH Alan Philip George Shannon L LukensShannon A Morrison, PhD, CRNP Taraneh Soleymani, MD Julie L Locher, PhDBarbara A Gower, PhD Robert E Sorge, PhD. "The Effect of Low-Carbohydrate and Low-Fat Diets on Pain in Individuals with Knee Osteoarthritis." Pain Medicine, pnz022, 13 March, 2019.