1 kg of human fat tissue contains about 7000 calories.

A 30 minute cardio session(60-70% of max heart rate), on the other hand, can burn roughly 200-400 calories.

Even if we count these calories as fully supplied from fat(which is far from reality), the resulting number of burnt fat is only about 50 grams, meaning that to burn 1kg of pure fat, 10 hours of cardio exercises are required at minimum.

I'm growing more and more pessimistic about cardio exercises as I look into these numbers. Am I missing something, or are cardios just not effective?

  • Source for those numbers ? They seem low. Every treadmill I've ever used would put 30 mins at around 600-700 cals. Do that 5 times a week and assuming you are eating right on your maintenance level you should average a 0.5 kg loss per week. Of course, a healthy diet is key as you can easily out-eat calories burned during cardio training. A single fast food meal can easily reach 1000 calories and would thrash even your best cardio sessions.
    – ApplePie
    Commented Nov 30, 2016 at 20:49
  • 1
    @AlexandreP.Levasseur the treadmills are known to exaggerate the actual results, plus they count the calories that you would've burnt simply sitting on the couch for the duration of that exercise. Here is one of many sources: popsugar.com/fitness/…. P.S, 600-700 calories per 30 minutes of cardio is extremely exaggerated.
    – Alex Lomia
    Commented Nov 30, 2016 at 21:03
  • thank you wasn't aware. Did suspect them to slightly inflated figures but did not expect them to include basic sustainment.
    – ApplePie
    Commented Nov 30, 2016 at 23:31

4 Answers 4


Not only that, but to burn the extra calories from cardio you have to subtract the amount of calories you would burn otherwise not doing anything. So really that 30 minutes of cardio only burns an extra 100-200 calories. This is also why they say diet is king. It's very easy to out-eat the calories burned from a workout. So no matter what you do, you need to get your diet in check.

Though, there are other factors in play. A 30 minute cardio session is only 2% of your entire day.

For one, that 30 minute cardio session will only help if you improve. So let's say you chose running for cardio. In 30 minutes you run two miles. In a couple months, you improve and get that up to three miles. Three miles = more energy spent in 30 minutes. Then you get even faster over time and get 4 miles. So now you've increased your energy expenditure in that same 30 minutes.

Then, there's EPOC. Shortly after a workout there is a period called EPOC (Excess Post-exercise Oxygen Consumption) which is a small window where your metabolism rises slightly in order to heal the damage done during the workout. The more damaging the workout (intense), the longer the EPOC period. Steady state cardio lasts maybe a few minutes. A HIIT (High Intensity Interval Training) workout will last maybe a few hours to a day. A full-body weightlifting program could last a couple days.

  • Thanks for an informative answer. As I understand, the intensive weight lifting sessions can surpass cardio exercises in regards to fat-burning by a long shot. So, is it safe to assume, that cardios are "way less than integral" part of losing fat and can be safely removed from training sessions?
    – Alex Lomia
    Commented Nov 29, 2016 at 15:55
  • 1
    Minute-for-minute, the amount of calories spent weightlifting is usually way less than cardio. So any given week, it is probably the same when you factor everything else in. Properly learning how to lift weights effectively and safely is also harder. The long-term advantage though comes in that you build muscle so your overall metabolism increases. If you do both, then the weight-lifting should take precedence.
    – DeeV
    Commented Nov 29, 2016 at 16:13
  • As you say damage I hope you mean replenishment of stores. Resting Energy Expenditure will help you a lot during the day for fat burning
    – bantandor
    Commented Nov 30, 2016 at 9:09
  • 1
    @bantandor Well that and the small muscle tears. Just general recovery.
    – DeeV
    Commented Nov 30, 2016 at 12:42

Even if you do nothing and sit there, you are still burning calories, because your body burns calories when you breathe. You heart needs calories to pump, your cell needs calories to survive and your brain needs calories to think.

The idea is, to consume less than what you spend, when it comes to calorie burning and losing fat. The idea of working out is to help you shed extra calories. So, don't be too concerned about if you are losing it all during a workout session or not, because you lose calories all day. Also, fat burning happens several hours after workout, because it's a slow process, not right when you workout. It's a cumulative and gradual process, and if you are working towards it, it's going to happen.


The answer to your question is yes, cardio is an effective means of fat-burning. However, this discussion typically centers on if it's more effective than other means and the answer to that question is no.

Overall studies show that a combination of proper diet, strength training, AND cardio is the most effective means of fat loss. The reason is because you cannot out exercise your diet, maintaining your muscle mass through strength training improves your metabolism and fat burning capability, and cardio helps widen your caloric deficit which is responsible for fat loss.

A person described as a Cardio Bunny is someone who dedicates a majority of their fitness lifestyle to cardio. Eventually, that person's fat loss progress plateaus because the body adapts to the workout, they lose weight, their caloric needs decrease, and therefore the same workout no longer has the same effect. Therefore, you can also think of a cardio only strategy for fat loss as an uphill climb towards your goal.


It's not that you are missing something but more that to loose weight you need to eat less, eating less is much easier than moving more (the other option).

Treat cardio as a way to be healthy and eating less a way to loose weight.

Doing both is great, but if your sole goal is either, do that.

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