Cardio’s Main Sell – It’s Easy
The treadmill provides a safe harbour for nervous recruits thrown into the meat grinder that is peak hours. It’s unassuming, simple, and nestled away from the confusing chaos. It also requires no instructions for getting in the game. You just jump on, pick a vanilla playlist, and shuffle along till it hurts to breathe. Repeat week on week, and the pounds should inevitably start to shift.
You don’t even need to bother with a gym membership for the few months in the year when outdoor jogging becomes viable. For such reasons, cardio is often picked ahead of lifting for people seeking weight loss. It’s an entry point into the world of fitness and self-improvement. And that’s a shame, because it’s forcing hordes of initiates to waste their time barking up the wrong tree.
The fact is, cardio is inessential to a weight loss programme. You don’t need it, and you might well be better off without it. Weight loss shouldn’t be about forcing the issue by sweating your way through oversized hoodies. We’ve been beaten over the head for decades with the ‘eat less, move more’ paradigm, and it doesn’t really pan out in practice.
Why Eat Less Move More Doesn’t Work
Here’s the catch with cardio and the logic of spending 30 minutes on the Stairmaster every evening. Expending more calories through exercise has an insignificant effect on your metabolic rate. A study comparing Hadza hunter-gatherers to Western cubicle monkeys found no difference in daily energy expenditure. Despite the fact that these groups lived on polar opposites of the activity spectrum.
The nomadic Hadza wander the wilderness for miles to find their dinner, whereas the average office worker would struggle to clock 8000 steps a day without being ordered to by their FitBit. And yet, they still burned the same when accounting for bodyweight. This curious result suggests that the metabolism runs as a constrained model that’s difficult to manipulate by simply jamming down the gas pedal.
The body seeks to keep energy expenditure within a narrow range, adapting to increases in physical activity by cutting back on other outputs. Think about how that might work in practice. You sweat puddles in a spin session, pat yourself on the back for those 450 calories, stumble home, then absent-mindedly graze on salted cashews while spread out over the couch.
The body likes homeostasis, and it’s extremely adept at defending itself against weight loss. Weight gain, not so much, but that’s hardly a threat to its survival.
The tail-end of this being, cardio isn’t going to shift much over the long term. There might be an initial honeymoon period, but inevitably the body will adapt, and the extra weight loss will fizzle out.
Other Downsides Of Cardio
But that’s not the only mark against the hamster wheel. Cardio is also inherently catabolic, which means it tears everything down, including metabolically-precious muscle mass. Losing excessive amounts of muscle over a weight-loss programme is tightly correlated to metabolic slowdown and compensatory mechanisms like hunger.
Combine cardio with low-calorie nutrient-depleted diets, without the anabolism stimulus of strength training, and you’ve primed the body to start shedding muscle tissue, upon which you’ll be blessed with the grind of crash dieting. The rampant hunger and cravings won’t resolve till you’ve regained all your lost muscle. Hence the rude rebound many crash dieters experience.
So you’re better off just keeping the muscle, and in order to do that, you’ll have to juggle your cardio dosage. Too much, you risk losing lean tissue. Too little, and you risk missing out on quality hours spent listening to your favourite podcasts.
Cardio itself is an extremely inefficient way to manipulate the energy formula, even when discarding the constrained metabolic model. You’re simply not burning much by surviving on a treadmill for 20 minutes. The numbers lie. The screen might read 300 calories, but that’s including the sum you’d have expended just by existing.
Then there’s the issue of high-impact training, with the extra muscle damage and joint stress that it brings to the party. There are plenty of ways to burn calories that steer away from impact, but unfortunately the most popular form involves plenty of pounding. Running can be a disaster for the ankles and knees with improper footwear. Which is to say, if you don’t do the right thing and go barefoot, the repetitive impact of heel-striking is going to destroy your knees. A slow merciless death for your unsuspecting joints.
Beyond that sad fact, that impact will also cost you points in recovery, which then jeopardises your ability to peak for the big lifts. Without the heavy weights to send a strong anabolic stimulus, lean tissue once again gets compromised over a weight-loss programme. So if you’re combing 10k runs with heavy weight training, you need to be weighing up your priorities.
But there is more to cardio than running, and there are plenty of activities you can swap in that don’t involve a ton of impact. Activities like the stairmaster, elliptical, cycling, swimming, and so on. The joints aren’t taking as much grief here, letting you rack up some caloric burn without shaving as much off your big lifts.
That being said, we still have to question whether the 300 extra calories you burnt up on the elliptical will actually translate to increases in energy expenditure, and thereby result in extra fat loss.
Cardio Vs Lifting Weights
Ultimately, the biggest downside of cardio is that it’s a waste of our most precious resource: time. Especially when you could be investing that time into remodelling the body into a muscular, fat-burning machine. Yes, we’re talking about the business of barbell bending. You’re a roughly equivalent amount of calories, with a whole cluster of extra benefits.
Whereas cardio is skewed towards fat burning, weight training preferentially uses glycogen, which improves carbohydrate utilisation, as well as being a potent tool for pushing you towards fat adaption. By depleting muscle glycogen in the absence of exogenous carbs, the body switches to ketones, an energy substrate made from triglycerides, also known as fats.
Lifting while in a state of ketosis will also push the body to reach greater levels of intensity while relying on ketones and triglycerides, most of which can be supplied endogenously, or from the body’s own stores. In other words, you burn more of your fat. The pinnacle of fat adaption comes when you don’t feel any dropoff in performance while fasted.
Even without a low carb diet, weight training still improves fat burning by increasing insulin sensitivity. More importantly, it ticks that box of providing an anabolic stimulus to stop your weight loss programme becoming an exercise in crash dieting. Both benefits are the crux of what training should provide be in a weight loss programme. The diet itself should shave the calories and induce weight loss.
Training, in turn, safeguards against muscle loss and accentuates the fat being discarded in the equation. Exercise shouldn’t be leveraged in the calorie formula. It’s too inefficient as a source of caloric burn, and any benefit soon gets fizzled out. In practically any scenario, weight training comfortably beats out cardio for the purpose of fat loss.
Benefits Of Weight Training For Fat Loss
- Building muscle mass
- Improving insulin sensitivity and improving fat burning
- Protection against injuries that could curtail a diet
- Preventing metabolic kickback on a diet
The Upside Of Cardio
My main point here is that cardio is an irrelevant tool for losing weight, and people are dedicating far too much time in the effort of burning calories, time that would be better spent on an activity that ticks more boxes. But that’s not to say cardio is a moot point. It has plenty of perks non-specific to weight loss.
In particular, it’s been shown to increase mitochondrial biogenesis, which is about as close as we’re getting so far to the elixir of life. There are plenty of competing theories floating around on the subject of ageing, and the case for the mitochondria is compelling. To sum up a nuanced topic, your mitochondria suffer attrition over the course of your life, depleting and inhibiting their function of providing energy to your vital organs.
So if we can actually stimulate the production of new mitochondrial units, that’s going to go a long way towards arresting the downward spiral. Cardio does that, weight training not quite. Lifting improves their function, rather than actually increasing their numbers.
Then you have cardio’s ability to work as a simple exercise in mindfulness, distracting you from the chaos of the past and the future. You’re tuning out and entering a state of intoxicating flow, otherwise known as the runner’s high.
From the perspective of the lifter looking to optimise his or her programme for incessant gains, endurance exercise also increases the effective volume one can subject the body to. You don’t have to rest as long in between sets, you pile on extra reps due to better fatigue management, and you bounce back faster between workouts. It simply makes you a more resilient specimen.
Zone 2 cardio in particular can work wonders for increasing carbon dioxide tolerance, otherwise known as that irrepressible feeling of panic that bubbles up when you duck your head underwater and try and replicate Tom Cruise’s Mission Impossible stunt.
The longer you can fight the urge to breathe, the better you get at tolerating higher C02 levels, which is critical for taking in oxygen from the lungs and into the body.
Simply put, improving your C02 tolerance improves your ability to oxygenate the body, reducing your need to haul in lungfuls of air as you navigate a steep set of stairs. Zone 2 cardio involves maintaining a sustainable but taxing pace while breathing exclusively through the nose, naturally creating air hunger and pushing up C02 levels. All without needing a conspicuous sub zero mask.
Benefits Of Cardio
- Mitochondrial biogenesis
- Stress relief
- Cardiac health
- Improved recovery
- Improved work output
- Increased energy through carbon dioxide tolerance
So I’m not making the case that cardio is irrelevant. Our ancestors did it and benefited through improved metabolic markers and tasty gazelle steak. There’s still a place for it on the apex table. It’s just not a fat loss aid, and it probably shouldn’t be done at the expense of weight training.