By Lindsay Wilson
Cardio is great for health but not always necessary for weight loss. The ‘best cardio for weight loss’ depends on your goals and fitness level.
Every January, every year, in every major city in the world people flock gyms and crank the cardio to ‘burn off’ the holiday excess. And every year their weight has a habit of looking a bit like the google trend for cardio. Peaking in early January, coming back a little before summer, but generally trending up year on year.
Using cardio for weight loss is classic example of Maslow’s hammer. A problem of over reliance on a familiar tool. Think of it like this:
if all you have is a hammer, everything looks like a nail
When someone asks themselves a question like ‘What’s the best cardio for weight loss?’ they often fail to recognise that the best tool for fat loss isn’t cardio at all, it’s diet. Cardio can be a great supplementary tool in lots of situations, but focusing solely on cardio is at best inefficient and at worst ineffective.
In this sixth section of The Fat Loss Framework we are going to look what the main benefit of cardio is, why it needs to complement diet and why it should match your fitness goals. We’ll follow this with a bunch of questions asking how you can make better cardio choices.
1) What’s the main benefit of cardio?
So although this framework is really about fat loss its simply wrong to write about cardio without mentioning the primary argument for doing it. Health!
When it comes to your health, a little bit of cardio goes a very long way. In fact when you look at the large cohort studies it seems that the first hour of exercise you do each week probably does as much good as the next ten in terms of your health.
To give you a very clear example of why I think anyone who cares about their health should at least do a little cardio I’ve grabbed some data from the long running Aerobics Center Longitudinal Study (ACLS) in the US.
In this graph we can see the relationship between people’s level of cardiovascular fitness and their risk of dying.
Basically . . . fit people live longer.
The fittest fifth of this population (measured with a maximal treadmill test) had half the risk of death per year as those in the least fit fifth. Both men and women in the fittest group had the lowest risk of death. And these are the risks after controlling for age, BMI, smoking status, hypertension, diabetes and family cardiac history. In fact there is plenty of evidence suggesting your aerobic fitness is a stronger predictor of mortality than other risk factors like hypertension, smoking, obesity and diabetes.
In addition to this pile of epidemiological data that suggests cardiorespiratory fitness promotes health there is also mechanistic evidence suggesting it can improve insulin sensitivity, blood lipid profile, body composition, inflammation, blood pressure and the autonomic nervous system.
So basically when it comes to health the argument for doing at least a little cardio each week is very strong.
Bottom line: Doing a little cardio each week is incredibly health
2) Will cardio guarantee weight loss?
Despite the mountain of evidence suggesting cardio is great for your health, it doesn’t guarantee fat loss. In fact trying to use exercise alone to drop weight can be breathtakingly ineffective. Let me explain with a quick example.
Imagine I weigh 180lbs and want to lose 10 lbs of fat. Each pound of fat has around 3,500 kcal of available energy, which is roughly the amount of energy it would take someone who weighs 180lbs to run a 4 hour marathon. So if I run the equivalent of ten marathons I can burn that 10lbs right? No
Firstly, I’ve counted total calories burnt, forgetting that I would have used some if I wasn’t running. Secondly, I’ll get fitter and more efficient as I train using gradually burning fewer calories unless I increase the pace. Thirdly, the running will make me tired and likely lower my activity during the rest of the day. Lastly, and probably most importantly, I’ll get hungry, likely eating back much of the exercise energy unless my diet is strict. So after 262 miles, despite being in great shape, I could easily drop just a few pounds of fat.
This story may sound a little hard to believe, but it’s been born out in numerous well controlled studies. In the chart below I’ve graphed the bodyweight and fat percentage change from a study where 400 middle aged women were randomised into groups where they did zero (control), one hour, two hours or three hours of cardio per week for 6 months at around 50% of their maximal heart rate.
The result? There were no significant differences in weight or body fat percentage across the groups. The more exercise the women did the better it was for their fitness and health markers, but the scale barely budged.
Across four groups of 100 middle aged women who did either 0, 330, 660 or 1,000 kcal/week of exercise over six months they could find no statistically significant difference in body composition. If you use simplistic calculations assuming all added exercise equates to fat loss then the 3 hour group should have lost over 7 lbs of fat. Instead they lost nothing at all.
Now before you get tempted to jump on the ‘exercise won’t make you thin‘ bandwagon I need to point out that this is just a single study. Although the results of cardio interventions for fat loss are mixed there is also plenty of evidence suggesting it can promote significant fat loss.
A good counter example is a 2013 study where they paid individuals $8/hour to work up to 5×400 kcal or 5×600 kcal of treadmill running each week. But in this case the target intensity worked up from 70% to 80% of maximal heart rate as the trainees got fitter. With both higher volume and intensity on their side the results looked very different.
Both of the exercise groups produced significant fat loss with the higher volume group losing an impressive 5.2 kg (11 lbs). Both groups also posted improvements in aerobic fitness, as you might expect, with perhaps the most impressive result being that all fat free mass was conserved. Particularly interesting was that if you looked at the individuals there was huge variation in the results, with some people losing over 10% of their body weight and other barely budging. Indicating the hunger response to cardio can vary a lot.
Although I think these two studies do make a case for higher intensity cardio, something we’ll get to later, that isn’t the main point. You see your fat stores don’t really care how much cardio you’ve done today. They care about what your deficit is. Cardio can be a strategic part of creating that deficit, but the deficit itself will always be determined by what you put in your mouth. So best to work out a strategy to control your intake before you jump on that treadmill.
Bottom line: Cardio does not necessarily result in fat loss
3) Will cardio affect your other goals?
The human body is incredibly adaptive. It adapts to caloric deficit by getting lighter and more frugal with energy use. It adapts to progressive resistance training by getting stronger and bigger. And it will adapt to cardiovascular training by getting fitter and better at using oxygen.
The type of adaptions that cardio elicits can vary a lot depending on what you do, so you should consider your cardio choice in the context of your other goals. To give you a quick fire overview of how the adaptions to exercise compete I’ve grabbed a little data from an excellent meta study that analysed the potential for interference between aerobic and resistance training. This chart shows how big the effect of strength, endurance or concurrent (both) training is on strength, fitness and body fat.
Here are the basic takeaways. Strength training is best for getting strong, endurance training best for improving aerobic capacity (VO2max) and concurrent training (both strength and endurance) is best for body fat reduction, though its a small difference.
I realize these results seem comically self evident, but you’d be amazed how easily people forget this type of wisdom when choosing their cardio. If your primary athletic goals are to get very strong (power lifters, weightlifters) you don’t want tax your central nervous system with strenuous cardio. You just need a solid aerobic base to maintain work capacity.
Likewise if you want excel at marathons, triathlons or road cycling there is little value in trying to maximise strength in the gym. You instead want to troubleshoot postural weaknesses in your body that are holding back your main training focus.
The primary reason you need to prioritise is that strength and endurance adaptions interfere with one another. Think of it as spectrum running from pure strength through to pure endurance work. Olympic weightlifters will be way off to the strength end, marathon runners far off on the endurance end and in the middle you’ve got speed athletes who need to sustain power in a way that requires both strength and aerobic conditioning.
This all sounds a bit complex but it really isn’t. If you want to get strong, spend most of your energy lifting. If you want to get fit, spend most of your energy running/cycling/swimming. If you want to get fast, spend most of your energy sprinting. And when you do complementary conditioning or strength work, make sure it does just that, complements your main goals.
Bottom line: Cardio should support your athletic goals
4) How much cardio should you do?
Cardio is great for health, but whether or not your should use it to help your lose weight really does depend. Here’s a few things to consider when planning your attack:
Efficiency: Firstly you need to recognize that it far easier to create the majority of you deficit by restricting calories than by adding exercise. Adding five hundred calories to daily expenditure typically takes an hour of serious effort, whereas cutting it from your food often just takes some smart planning.
Muscle: If you are trying to ensure you lose fat rather than muscle then your first exercise priority each week should be strength work. If you have limited time to exercise then its probably a good idea to get in two full body strength workouts a week first. You can always add cardio, as warmups or finishers, to these workouts.
Occupation: If you have an active job, or a naturally high energy expenditure, cardio is less important as you can already cut at a high caloric intake. In contrast if you spend your whole day sitting at a desk, then a smart cardio program may avoid you dropping calories horribly low.
Pleasure: If you like to run, or cycle, or swim then great, but don’t do cardio you hate. This can trash your motivation. Try to find something you like. If you only enjoy lifting then create circuits or complexes that last at least 30 seconds per round. These become largely aerobic and might be less tedious.
Hunger: Cardio seems to effect peoples hunger in varied ways. If you aren’t on top of your diet it can be easy to eat back all the energy you burn exercising. This is particularly true if you overestimate the energy you burn working out, or feel entitled to extra food for your efforts.
Now I realise this is a jumble of ideas, so let’s talk about a more intuitive metric. Hours of cardio per week.
- None: Good for people with active jobs, limited training time or starting a diet. Can help focus the mind on nutrition.
- 1 hour/week: Great for people who care about their health, but don’t enjoy cardio. Ideal conditioning for the strength focused.
- 2 hours/week: A nice amount for recreational athletes training for endurance events or people with really stagnant work lives.
- 3+ hours/week: For people that actually love endurance sports. To be avoided unless you really find pleasure in the process.
Regardless of what you aim for make sure diet remains your primary tool for creating the deficit and you are aware of what it does to your hunger. There is also no reason to pick one option. Periodizing your cardio through cycles of doing nothing, low intensity or high intensity can be both mentally and physically useful.
Before I wrap up this section I want to add a little graph about how many calories exercise actually adds to your daily burn, as people often overestimate this. These are what we call ‘net calories’ as I’ve subtracted the amount of energy you would have used if you’d been relaxing instead of exercising.
What you can see is that regardless of the type of cardio you choose the volume of extra calories burnt is largely a question of intensity. Doubling the speed at which you run, cycle, swim or walk will typically more than double your net burn. Then again I don’t really think calories burned should be your first consideration when thinking about cardio.
Bottom line: Cardio can be a useful addition to diet for many people
5) What type of cardio should you do?
Although I could suggest a few ideas for cardio here (like cycling intervals) I actually don’t think advocating a particular mode is a good way to address this question. One of the big traps I see all the time with cardio is choosing something that is too hard to sustain. This happens every January 1st when people try to go from zero exercise to hours of cardio a week. Although this kind of approach can work for really disciplined people, it invariably fails for most.
The major problem with doing something difficult (like an hour of cardio each day) is that it requires a high degree of motivation. And very quickly when you’re tired, work is busy or life gets hectic your motivation goes missing, quickly followed by your cardio routine.
Interestingly behaviour change experts actually find the opposite approach is a more effective way to developing a habit. Instead of something hard they start with something so small and simple that you pretty much design out the need for motivation. Then once you’ve developed a consistent habit you can tweak the the routine more optimal.
Here’s how it looks visually:
We have three basic steps. A ‘cue’ to trigger the ‘routine’ we want followed by a ‘reward’ to reinforce that behaviour. For cardio this could be ‘after I turn the coffee machine on in the morning I will do 100 star jumps then enjoy my espresso’. Obviously the cue in this case is turning on the coffee machine, the star jumps are the routine and the reward is the coffee.
At first glance this seems too simplistic, as 100 star jumps is only two minutes of exercise, but that’s exactly the point. The star jumps are fast to do, need no equipment and can be done in your pyjamas if you like. The process is so simple you design out the need for motivation.
But attach something simple to a regular cue and you’ll be surprised how quickly you can develop a cardio habit. Then to star jumps you add burpees, running on the spot, a few pushups, some situps . . . and suddenly every weekday morning your doing 15 minutes of exercise and you have an actual routine you can adapt to meet your fitness goals.
Now obviously my 100 star jumps is an arbitrary example. The point is to choose a type of cardio that is really easy to fit into you day. That could be adding walking after breakfast, cycling to work, running at lunch or youtube workouts after you put the kids to bed. The key is to start with something simple and then build on it once you’ve established the habit.
Bottom line: Simple cardio routines are easier to start with
6) Do you enjoy your workouts?
Although cardio by itself doesn’t always promote weight loss we know it is hugely important for keeping weight off once it has been lost. Among members of the National Weight Control Registry (NWCR), who have lost an average of 30kg (66lbs) and kept it off for over 5 years, weekly exercise activity averages 2,800 calories which is essentially an hour a day.
When you are just getting started with cardio keeping it simple is great. This reduces your reliance on motivation and makes it easier to build a habit. But as times goes by you are going to need more than simplicity. Your cardio will actually be rewarding for you to stick with it.
What we want to do is close the loop. Although a regular cue and a simple routine are great foundations, in the long term we are going to need more reward than a cup of coffee. Obviously a cardio habit could bring many benefits including health, fitness, weight loss, relaxation, improved sleep, better mood . . . And if any of these work to motivate you then great, but personally I think the thing that changes everything is pleasure.
The brutal truth is that for many people ‘cardio’ is just some horrid slog that they push through because its good for them, or helps with weight loss. And that’s quite sad. The very act of calling an exercise ‘cardio’ is quite denuding, almost implying its a means to an ends. Pleasure changes that.
Runners love to run. Swimmers love to swim. Cyclists love to cycle. Dancers love to dance. Footballer love to knock a ball about. If you can find pleasure in something that gets your blowing the you are on to a very good thing.
Bottom line: If you enjoy it then you’ll keep at it
7) How intense should it be?
If you’ve found a type of cardio that is simple enough to fit into your life and that brings you pleasure then you’re onto a winner. The only thing to ask yourself at this point is can you adapt the intensity of your routine to get even more out of it.
I think the best way to think about cardio intensity is like a toolbox. But instead of having a screwdriver, a hammer and a chisel, what you’ve got is low, medium and high intensity. And before you decide which tool to reach for, you need to ask yourself what the job is.
Lets talk through our tools:
1) Low intensity steady state (LISS)
If you can hold a conversation doing it then its probably low intensity. This is things like jogging, gentle cycling, brisk walking . . . anything that gets your heart rate into the 45-65% of maximum range but isn’t overly taxing. Low intensity cardio is a great way to get basic conditioning, and burn calories, without taxing your body in a way that will require significant recovery time. It’s major drawback is that it can be time consuming and boring for many people.
2) Medium intensity steady state (MISS)
Medium intensity cardio is basically endurance training. Whether its running, cycling, swimming this is when someone’s heart is typically in the 65-85% of maximum range and they are building their aerobic base. Although medium intensity cardio is very healthy, and probably the fastest way to burn calories, it is often avoided by strength and physique athletes as it elicits endurance adaptions that interfere with strength and hypertrophy goals.
3) High intensity interval training (HIIT)
High intensity interval training is short bouts of very intense work, essentially sprints. The work interval typically last 20-60 seconds and is intense enough to push the heart rate up above 85% its maximum. The major benefit of interval training is that forces you to work anaerobically, causing hormonal and muscular adaptions that can be useful with fat loss. It is also extremely time efficient. The downside is it’s very demanding, so you need to be fit and prepared to tolerate the discomfort that comes from doing it properly.
If you are fit enough, and can recover in time for other workouts, high intensity sessions are probably the best cardio for fat loss. Numerous studies in recent years have shown intervals outperform steady state in terms body composition. Indeed the the meta study I mentioned earlier found that the biggest reductions in body fat were produced at the highest heart rates.
This graph shows that cardio seems to become much more effective for fat loss when we cross 90% of our maximum heart rate. At this point the effort is so intense that you are forced to work anaerobically. Although the mechanisms aren’t completely clear it seems that normal aerobic training mostly improves your ability to pump oxygen around your system, whereas more intense intervals create adaptions in the muscle themselves which can improve fat and carbohydrate oxidation capacity.
Now although I think there is a strong evidence base to suggest high intensity cardio is the most efficient cardio for fat loss, that doesn’t mean its always the best tool for the job. If you are heavily overweight, or just starting back in to exercise, low intensity is a much better bet. It can help you build basic fitness while avoiding much of the impact and physical strain associated with higher intensity work. Low intensity work is also ideal for strength focused individuals who need to save their legs for lifting, or for almost anyone trying to increase their body temperature before something more strenuous (warmups). Medium intensity cardio also has its place, particularly is you covet cardiovascular health.
It basically comes down to choosing the right tool. I’d highly recommend keeping your options open.
Bottom line: Cardio intensity can be varied based on the individual
8) What’s the best cardio for you?
Although diet is key for weight loss, because it dictates the deficit, I do think its a great idea to include a least a little cardio for health and fitness.
If you want to find something that you might actually stick you really need to make sure it fits you and your life. Preferably it would be simple, fun and effective. ‘Simple’ making it easy to start, ‘fun’ to help you to stick with, and ‘effective’ to ensures it produces the results you want.
In an ideal world everyone could come up with a cardio routine that is simple, fun and effective. And if you can nail this first go, more power to you! But often this is far easy said than done. What I think works well is to try and find something that ticks two of these boxes, and then go searching for the third. Let me give you some examples.
Mountain biking is fun and effective but difficult to fit into everyday life. Finding a simpler way of fit cycling into your day could make it more regular. The obvious opportunity is your commute. These regular miles logged during the week might not be glamorous, but they could set you up for some serious single track at the weekend.
Walking is simple and fun but not always as effective as we might like. Rather than turn you walking into running, which might ruin the fun, you could instead gradually make a concious effort to walk faster. You could do this by feel or using some technology like a pedometer, fitbit or smartphone.
Running is both simple and effective but many people find it boring. Lets say you’ve started something like couch to five kilometres and although your improving you wouldn’t call it fun yet. At this point you desperately need to meet some runners. Find your local parkrun and give it a go. This will be more fun that running alone and you’ll meet a tribe of people that understand what it means to run. Hopefully they’ll convince you to do a race, which might turn you from a jogger into a runner.
Bottom line: The best cardio fits you and your lifestyle
9) Winning
Cardio is not necessary for fat loss. A solid strength program and a meticulous diet can often be enough to get people shredded in style. That said I think you’d be nuts to exclude cardio from your toolbox completely as it can be an incredibly useful addition to your diet at certain times. Of course even if I thought it served no purpose for fat loss I’d still recommend it to anyone who will listen.
In fact I think finding a form of cardio you like is akin to winning a lottery. You see cardiovascular fitness is one of the strongest predictors of life expectancy. And doing as little as an hour a week of medium intensity cardio can have profound health benefits.
Let me show you what I mean . . .
A few years back a number of papers highlighted the potential dangers to the heart of excessive endurance training (think ultramarathons and ironmans). Based on this researchers though it might be a good idea if to see if there if they could find a threshold where fitness actually begins to increase your risk of dying, instead of improving it.
Here’s what they found.
Among the 38,000 patients who were reasonable fit (METS>10) the were unable to find any evidence of an upper threshold for mortality benefit. The fitter people just got less and less likely to die soon.
On seeing this graph you could question whether this relationship is actually causal. After all there might be omitted health variables, reverse causality from genetics or other things driving the correlation.
But seriously, look at that graph?! My reaction was to buy a pair of running shoes and start enjoying more carbs.
Bottom line: Fit people live longer
Summing up
Cardio is phenomenal for your health and a useful complement to diet for weight loss for many people. Finding a type of cardio your actually enjoy can make you healthier, fitter and allow you to eat more. If you can find something that’s fun, simple and effective you’ll be much more likely to stick with it.
Up next will ask if you should lift weights to lose weight.
