I like to do cycling and I want to lose weight through cycling. But my friend told me about cardio instead of cycling, since cycling burns calories at a much slower rate. Is it true? So what's better to lose calories faster, cycling or other exercises?

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    Tell your friend he needs to do his "cardio" for three or four HOURS. Or tell him to keep his speed at 40 kph or higher. Then ask him if "cycling burns calories at a much slower rate". Your friend is, umm, misinformed. Nov 3, 2022 at 10:42
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    Any exercise programme will have different things mixed together, to minimise boredom and work different muscles. You could do mix it up with cardio one day, ride your bike the next day, and so on . Yoga, wood-chopping, and running on other days, then have a light day where you go for a walk. You do you.
    – Criggie
    Nov 3, 2022 at 12:10
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    What safety concerns do you have? (I ask because you tagged this question with "safety")
    – Paul H
    Nov 3, 2022 at 15:54
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    Ignore all advise from someone who says you should do cardio instead of cycling. Best advice would be to do something you love, not too much, not too little, above all, don't get injured. If you love cycling more than any other exercise, there is no better activity, its low risk of injury, and you can do as little or much as you want as often as you want.
    – mattnz
    Nov 3, 2022 at 22:27
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    @Paul Safety is a big concern for many people getting into exercise. For people who are out of shape or unused to exercise, (or both), injury prevention while getting back into shape should be their #1 priority, and any advice given should be focused on injury prevention over results. It is hard to get results if you are nursing injuries and cannot exercise. (Which is why I would caution against gym based 'cardio' training, where one hour of 'one hour max' effort is considered 'Cardio')
    – mattnz
    Nov 4, 2022 at 2:45

6 Answers 6


The answer to the Title question, "Is cycling an aerobic or anaerobic exercise?", is yes.

Aerobic exercises are endurance-type exercises that increase a person’s heart rate and breathing rate over relatively long durations. Anaerobic exercises are exercises that involve short bursts of intense activity.
Aerobic vs. anaerobic exercises: What to know

Taking a long ride will provide aerobic exercise. You'll be burning more energy than usual, and will be continually breathing faster than usual in order to maintain a consistent level of oxygen in the blood.

If during that ride you occasionally have a quick sprint or a short steep climb, so that when it's over you find yourself needing to stop and breathe very heavily, it's anaerobic. The oxygen in your blood will be briefly and temporarily depleted.

As for your purpose, in general, exercise by itself is not a good way to lose weight. Exercise does burn calories (about 10 per minute for moderate cycling), but for most people the major effect of this is that they end up feeling hungrier afterward, and often end up eating more calories than what they just burned.

Exercise is a good thing, and given what site this is, obviously cycling is the best form of exercise, but it should be used in conjunction with other methods of weight loss.

The exercise that really loses weight is the exercise of restraint.

Eating because one feels hungry is a great way to gain weight, not lose it.

Following exercising, one will feel hungry, and that is good. It is proof that some fat has been burned, and the body is simply saying that it needs to be fed so it can refill the fat cells. To act on that request will simply restore any weight that was lost due to the exercise, and perhaps some more.

Most people, especially those that are overweight, will be exhausted after 45 minutes of moderate cycling. But in terms of weight, they could have lost twice as much simply by not eating a Big Mac Meal and feeling hungry for a few hours.

In fact, the general rule is that the most effective way to lose weight is to feel hungry.

Exercise is great for strong bones, better endurance, and more effective respiratory and circulatory systems. But it should not be seen as a quick and easy method of weight loss.

And always avoid fructose. It is the one carbohydrate that doesn't "spoil your dinner". It has an extremely low glycemic index and can take hours before it might be converted to blood sugar (dextrose), though by then it is more likely to have been stored as fat.

(Long distance cyclists might want to take the opposite advice.)

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    OTOH eating during exercise takes more thought than eating when it's just a stroll to the kitchen to get food, even if you have food to hand on the bike. I actually tend to eat less on days when I spend many hours riding than on sedentary days. I'm also not alone in finding that on fasted (before breakfast) or unfed (after a meal but with no calories during a ride of several hours) rides, it's only when I stop that I get hungry.
    – Chris H
    Nov 3, 2022 at 16:26
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    Also, building cycling muscles and getting fitter will increase your basal metabolic rate; if the goal is weight loss this will make a disciplined approach to eating go further
    – Chris H
    Nov 3, 2022 at 16:27
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    Exercise can totally help with weight loss. My commute is 6km in each direction and takes 20 minutes. According to my power meter I burn more than 100kcal in each direction. That’s 200kcal more per day I can eat just by commuting. A two hour bike ride can easily burn more than 1000kcal which is a whole pizza. I’m not that fit and relatively light at 66kg. A fitter, heavier person would burn even more. I’ve counted calories, I eat more than 2500kcal every day and I’m not gaining weight because of the exercise.
    – Michael
    Nov 3, 2022 at 17:23
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    @Michael, I didn't say that exercise doesn't help with weight loss. My point was that unless one also takes calorie intake into consideration, it's very easy to unwittingly eat extra to make up for the burned calories. Exercise is a good idea even if one isn't trying to lose weight, but for weight loss it is only part of the answer, not the answer. Nov 3, 2022 at 17:47
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    Regarding fructose: it's the main carb in fruits. Fruits can help with satiety as they have fiber and water, and they have vitamins. By avoid fructose, I assume you mean avoid stuff sweetened with fructose syrup - but isn't that not terribly different from just reducing your dessert intake?
    – Weiwen Ng
    Nov 3, 2022 at 19:54

Cycling at moderate intensity is mostly an aerobic cardio exercise.

How many calories you burn in an hour depends on your power output. A heavy professional cyclist (90kg, 6W/kg 5W/kg) can probably burn around 2000kcal in a single hour when cycling all-out. For an amateur at a less-than-all-out intensity it’s more like 500–1000kcal in an hour.

Other cardio exercises like running or rowing have similar rates.

In my opinion cycling has several advantages for burning calories:

  • Even complete beginners can do it for >30 minutes. With a bit of training two hours are very achievable.
  • Risk of overuse injuries is low and time for recovery is short. If you don’t push too hard even an amateur can go cycling for a meaningful duration every day.
  • The above two points are partly possible because intensity can be adjusted in a wide range thanks to gear shifting.
  • With a power meter you can measure calories burned pretty accurately.
  • You can integrate it into your daily life. Commuting, shopping, visiting friends or family, going to a restaurant … many of those activities require travel in a 5–25km distance which is ideal for cycling, even for a beginner.

That being said, there is no magic recipe for burning calories. If you are consuming 3000kcal every day, are unwilling/unable to reduce intake and still want to lose weight you’ll simply have to exercise for more than an hour every day. And that hour of exercise can be negated in 5 minutes by eating two big chocolate bars.

  • 4
    Your calorie estimates may be a bit high. I’m not 100% certain. I can report that a moderate pace 80 mile solo ride, with me at 135-145 lbs, typically burns a reported 1900-2200 calories over 4-6 hours moving time. (NB: that’s estimated calories expended by body, not measured work done by the power meter; there is an assumption about the body’s gross mechanical efficiency, but that parameter varies by individual). Either way, it’s true that long rides can burn a lot of calories, and they’re low impact.
    – Weiwen Ng
    Nov 4, 2022 at 16:01
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    @WeiwenNg: I’m currently very out of shape due to two hip surgeries. I’m 66kg, 1.8m. On a 1h ride I can still do 167W average power (not all-out and there are a few kilometers of city traffic) for 635kcal (according to Garmin). Of course a person who’s lighter or less fit (or less motivated) can be much lower.
    – Michael
    Nov 4, 2022 at 17:16
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    2000kcal in a single hour That's 556W. As @WeiwenNg said, that might be a bit high. Bradley Wiggins at 6'3" topped out with an FTP around 450W or so IIRC, maybe a bit higher. Hard to believe someone could add another 20% to Wiggin's lung capacity to sustain a 550W+ FTP no matter how big. Nov 4, 2022 at 19:38
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    Andy P also told me in the chat that heavier pro riders seem to have lower FTP. So I guess for a 90kg pro rider around 5W/kg would indeed be a better assumption. Still ends up around 2000kcal in an hour. Not that those numbers are relevant for us mere mortals, but it’s always interesting to see where the human limits are.
    – Michael
    Nov 4, 2022 at 20:52
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    @EricDuminil A kcal burned by your body is almost exactly 1 kJ of mechanical energy output. Human bodies are a bit less than 25% efficient, and 1 kJ is .23 kcal - making the conversion just about perfect. So if you measure the kJ you expend exercising, you pretty much also measure the calories you burned. And yes, the calories that usually get reported as "burned" by various other methods usually exceed measured kJ, often by quite a bit - they're bogus. Nov 5, 2022 at 23:22

You have several questions mixed into one here. You're asking about "losing calories", and about losing weight. Those are two different things. You also ask if cycling is aerobic or anaerobic, and if cycling is the best option for losing weight. Those are all different questions.

Burning calories, and aerobic vs anaerobic exercise

You are constantly burning calories. Even sitting still, you're still burning calories as your heart beats, your lungs inhale, and your body does everything it does to keep you alive. All those things require energy, which your body obtains by burning calories. There are several different ways in which your body burns calories, depending on what you're doing.

During aerobic exercise, you are using slow-twitch muscle fibers. Aerobic exercise is less focused on intensity and more on length, such as a long bike ride. Slow-twitch muscle fibers burn calories using your stored fat reserves and the oxygen in your blood, along with small amounts of glucose (sugar).

During anaerobic exercise, you are using fast-twitch muscle fibers. Anaerobic exercise is faster-paced and much more intense, such as sprinting. Fast-twitch muscle fibers burn the glucose in your blood stream, and leaves lactic acid in the process, causing that muscle burn that occurs when sprinting.

Both of those methods are burning calories.

Losing weight

Anaerobic exercise burns calories faster, since you're burning through all the sugar in your bloodstream. However, you do need to resupply the calories that you're burning. If you use too much of the glucose in your bloodstream, you'll experience exhaustion and fatigue, due to not having any fuel left to burn. Remember, aerobic axercise also needs small amounts of glucose to function. You need to refuel, with carbs and sugar, often when doing anaerobic exercise or risk hypoglycaemia (low blood sugar), a dangerous condition.

Aerobic exercise burns calories more slowly, but does so from your fat reserves as well. Consuming carbs before and during aerobic exercise is recommended, in order to maintain your glucose levels. If you don't eat beforehand, your body automatically goes into preservation mode; you won't burn fat, because your body is making sure to not burn too much because it hasn't had anything, and is trying to make sure you don't starve. If your goal is to burn fat, eat and drink before and during an aerobic session; less so afterwards.

Cycling can be both aerobic and anaerobic. Whether your ride is predominantly one or the other depends entirely on how you're riding that day, as well as what discipline you're riding. Road cycling tends to be much more aerobic, with long days in the saddle spending hours on end pedaling. Mountain biking is often much more anaerobic, with lots of short sprints to get up small hills, perform jumps, get over bumps, etc. It all depends on whether your specific training ride is designed more for an aerobic session or anaerobic session.

Is cycling the best option for burning calories? It's hard to say. Other sports are more or less demanding on other parts of the body, while cycling is very legs-focused. It's possible that other sports that move more of the body - such as swimming - may be more efficient at burning calories than cycling. Hoever, it is hard to beat cycling when it comes to aerobic sessions; most sports are quite difficult to maintain for six-plus hours, while it's quite doable to maintain that on a bike.

Ultimately, any exercise is going to burn more calories and more fat than not doing anything. Pick a sport that your enjoy, and work on it - that's more important than the exact count of calories you're burning doing cycling vs other sports.

Information in this answer is based on my personal experience as a competitive rider for several years, as well as information I recieved when doing my coaching certification in 2019.

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    "leaves lactic acid in the process, causing that muscle burn that occurs when sprinting". Not really. See: Truth about lactic acid, fatigue, muscle soreness - Sports Illustrated. Nov 4, 2022 at 2:48
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    "If you don't eat beforehand, your body automatically goes into preservation mode; you won't burn fat, because your body is making sure to not burn too much because it hasn't had anything, and is trying to make sure you don't starve.". One preservation mode is ketosis, where fat is essentially the only source of energy. ¶ Just this afternoon I did 30 km of up and down hill cycling and always felt like I had plenty of energy, yet I didn't have breakfast until 5:30 pm., having last consumed any calories before 8 pm the night before. Nov 4, 2022 at 2:57

It really depends on the effort you are making. If you produce power, the body must burn some energy storage, quick ATP, blood sugars, then later finally body fats. If your effort on the bike is higher then when doing other cardio activities, you should burn the body fats faster, but you first have to get into the fat-burning regime. That takes some time for all activities.

Normally, cycling is definitely an aerobic activity.For short burst and speeds it can also be anaerobic, but only for short time intervals with very increased effort.

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    Doesn't "short time intervals with very increased effort" apply to all anaerobic exercise?
    – ojs
    Nov 3, 2022 at 17:29
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    @ojs Yes, that is the point. My expression is perhaps not the best. Nov 3, 2022 at 18:32

One point that others haven’t covered. Cycling is low impact, and thus it’s comfortable to do it for longer than running. Cycling can be engaging, i.e. it’s very different from an exercise bike, treadmill, or rowing machine in the gym, so it can be pleasant and mentally engaging to do it for longer periods than those activities. Because it is possible and pleasant to do it for prolonged periods, it can be better than other exercises for weight loss.

Naturally, the trade off is that burning more calories takes more time, and you have some barriers to entry in terms of needing to get equipment and relevant skills, e.g. riding, navigating, basic repairs.

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    Low impact? is it low impact when I ride my bike and reach my max heart rate in 5 minutes? Is anaerobic training "low impact"?
    – Christine
    Nov 4, 2022 at 20:25
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    @Christine Low impact means there are less stresses on the body - compare riding with running where every footfall hits the ground with some force, generating a shock to the body which affects joints and tissues.
    – Criggie
    Nov 4, 2022 at 22:22
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    @Christine other potentially high-impact sports include many ball games. Other low-impact sports include swimming, yoga, rowing. What you describe is basically going for an all-out 5 minute effort. That could be thought of as a semi-anaerobic effort (specifically, you are probably operating near your VO2max, i.e. your aerobic energy system is near max, and you are using a lot of anaerobic power also; think like a mile run). Everyone's lungs are burning at that effort level, no matter how well trained. But that's not 'impact' in the sense I'm using. Also, you could start easier.
    – Weiwen Ng
    Nov 5, 2022 at 12:08

It's quite easy to know if an exercise is aerobic or not, but first a bit of physiology.

First, your muscles contain various types of fibers: slow fibers for long sustained low intensity effort, and fast fibers for short bursts of high-intensity effort.

These are exercised and developed differently by different types of efforts: basically, your body will become better at doing what you do often. If you only run marathons or only do long bicycle rides at moderate speed, you will train your slow twitch fibers for endurance and you will look like a marathon runner. If you only do sprints, then you will get huge fancy muscles, along with some endurance, but not as much as you'd hope, and the guy with the spindly legs will leave you in the dust on climbs.

Second, your muscle cells get their energy from tiny powerplants called mitochondria which burn fat, glucose, and other stuff.

Mitochondria use a range of chemical pathways to burn fuel, they may use several pathways at the same time, but they prioritize the most efficient one depending on what fuel is available, and how much oxygen they get.

The most efficient is aerobic metabolism: burning fuel using oxygen, which exploits all the energy in the fuel and degrades it down to water (which is recycled) and carbon dioxyde (which you breathe out).

The absolute best is burning glucose, it has higher power throughput than burning fat, so glucose has priority over fat. This has an interesting side effect: if you eat a lot of sugary things before exercising, your mitochondria will be very happy to burn it, and they won't use any fat.

The amount of aerobic power you can produce depends on how much oxygen your body can transport to your muscle cells. If you exceed that power, all the oxygen is used up as fast as it comes in, and the excess power is produced by converting glucose into lactic acid without oxygen. This can produce huge power, but the lactic acid accumulates which manifests as a burning sensation in your muscles. When that occurs, it doesn't mean you're over the limit, rather it means you've been over the aerobic limit for a while already. If you keep going, lactate will keep accumulating and you will either stop or throw up.

Just think of a video game: anaerobic is your stamina gauge. It has a certain capacity, it is consumed when you sprint, and when it runs out, your power drops significantly.

Meanwhile, your aerobic capacity is the amount of effort you can sustain at a constant level for a long time, say longer than one hour.

So, to answer your question. Since "effort level" is subjective, let's use an objective measurement instead: time.

A power level you could sustain for many hours: aerobic, burning a mix of glucose and fat. This is pleasant, not really taxing, and if you do it for an hour you arrive feeling good, rested, it doesn't feel like exercising.

A power level you could sustain for 1-2 hours: aerobic, burning mostly glucose.

A power level you could sustain for a few minutes or less (sprinting): aerobic glucose + anaerobic glucose.

When you run out of glucose, power output drops significantly ("hitting the wall") which is not fun, and sprinting is almost impossible.

After sprinting, when you slow down to recover, more oxygen becomes available to recycle all the produced lactates back into pyruvate and glucose. So your thighs stop burning and you feel better without all that lactate. If you don't slow down enough, and stay at the aerobic limit even after a sprint, then all the oxygen is used up to produce power and lactates are not recycled, so your thighs keep burning. If you slow down too much (or stop) then your breathing and heart rate will slow down and lactate recycling will be slower. The optimum seems to be the most pleasant, leisurely pace.

So one important thing is when doing "anaerobic" high intensity interval training (aka sprinting between traffic lights), the cooldown period after the sprint is part of the exercise! During this cooldown your body must either recycle all the lactate that was produced or use it as fuel. Recycling it uses energy and oxygen, so every anaerobic effort is followed by aerobic metabolism to clean up the mess. Anaerobic effort doesn't burn any fat, but the cooldown can burn fat. Later, at home when you rest, you will notice elevated heart rate for several hours because your body is working to replenish glycogen stores, build new muscle, etc.

So, basically, to burn the highest percentage of fat in proportion to the total fuel your body will use, you must ride at a moderate effort level for a very long time. This works but it is not convenient as a weight loss mechanism because you need to spend the whole day on a bike. It is only practical if you do a long bicycle trip. Also the effort is low, so while your body is using more fat than glucose, it is not burning a lot of energy.

The most important thing about exercising is to actually exercise, and in order to do that, it should be fun and pleasant, which means it should be varied and/or practical. If you ride fast, slow, uphill, downhill, with a good mix of cardio, sprints, cooldowns, eat a bit of sugar but not too much, a bit of high glycemic "slow" sugar but not too much. One day a big mountain, the other day lots of small hills, sprints between traffic lights, set yourself challenges, go with friends, etc. The goal should be to get back home well exercised but not entirely exhausted. Then your body will work at elevated metabolism for many hours and burn more fat while you do nothing at all (this requires not eating a huge feast after the ride).

Now about your "knowledgeable" friend:

If you keep your heart rate on the "cardio" range on a bike, you're doing cardio. What makes it cardio is when you keep your heart rate in a specific range for a long enough amount of time, it doesn't matter how you do it, push-ups, cycling, walking uphill, running, whatever. If you want to do it with your arms, you're gonna need pretty big arms though.

For example when the weather doesn't allow cycling, I do cardio by walking up a hill. 300m altitude in 20 minutes is 15m/min, at 100 kilos, about 250 watts, then I walk down.

In fact the only way to do cardio is outside, not in an overheated gym.

If you have any kind of decent leg power output... say, you produce 200 Watts power output on your bike, you will also produce 800 Watts of heat, that's as much as a small electric heater. Outside, you get free air cooling, but to survive this for any length of time indoors, you need a big fan unless the aircon is set to a temperature that would make everyone who isn't doing cardio freeze and leave the gym. In the usual gym which is heated to more than 20°C, forget it. You will overheat, sweat buckets, and exercise at a much lower intensity that you could.

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