How Much Cardio Should You Do to Lose Fat?

Some say you don’t need any cardio, whereas others say you’ve got to do it every single day. But after speaking to some of the top natural bodybuilders in the industry, interviewing the smartest experts in the world, and reviewing the latest science, here’s what I found.

But first, we need to figure out how helpful cardio actually is for fat loss. And the answer might surprise you. While cardio is great for heart health, longevity, and provides plenty of other benefits, it’s not nearly as effective as most people think when it comes to losing fat, at least in the way most people do it.

The Constrained Energy Model

You see, typically you’d expect if you did 300 calories worth of cardio, you’d burn 300 more calories that day. But back in 2016, researcher Herman Ponzer published what is known as the constrained energy model, proposing that the more calories you burn through cardio, the more your body will try to save energy and burn fewer calories the rest of the day to protect its fat stores. And it does this subconsciously by taking fewer steps the rest of the day or little things like not moving your hands around when you’re talking, for example.

Not to mention diet compensation as well. Some people tend to subconsciously eat more in response to doing more cardio to the point where the 300 calories of cardio you did can theoretically cancel out completely.

The Compensation Effect

Unfortunately, shortly after this research came out, major news outlets took interest and shared it using clickbait headlines that made it seem as if exercise was pointless for fat loss. Now, although this is an exaggeration, The Compensation Effect is definitely real and well documented. Most research has shown that people who start doing cardio without any changes to their diet tend to lose only 20 to 50 percent of what they’d expect from the calories they’ve burnt.

Different Types of Cardio

But you probably wonder, what about Different Types of Cardio? Surely sprints and HIIT-type workouts we see all the shredded influencers doing will be great for fat loss, right? Well, Daniel Plotkin, one of our Built with Science researchers, recently published a study comparing all Different Types of Cardio and fat loss. Here’s what he found:

So what we did is we took all the studies that we could find that compared high-intensity training—so training that was either sprint intervals or biking intervals—and compared that to low and moderate-intensity aerobic exercise. So that could be incline walking, that could be moderate-intensity cycling. So we wanted to see which of these modalities created more fat loss.

And what we found was that there was no difference between these two modalities at all, which wasn’t super surprising. But what was surprising is that whether it was high-intensity interval training or moderate-intensity training, there was essentially no fat loss effect even compared to nothing. I think the magnitude of effect was 0.5 pounds over eight weeks of aerobic training.

What we can conclude from this is that at least at the doses given for the high-intensity training—the average weekly minutes was 30 minutes and for the moderate intensity, it was an average weekly minutes of about 120—cardio alone isn’t very effective for fat loss.

High Doses of Cardio

Okay, but what about even higher amounts of cardio? Does that lead to more fat loss? Well, in studies like this one by Ross and colleagues, very High Doses of Cardio—in this case, doing 700 calories worth of cardio every single day, the equivalent to about one to one and a half hours of jogging—does actually lead to quite a bit of fat loss. So without changing your diet, you’ve probably got to do a whole lot of cardio for it to have a meaningful effect on fat loss, which isn’t a very efficient or realistic approach for most people.

Effective Fat Loss Protocols

But I didn’t make this video just to tell you that cardio doesn’t work because it does, but only when you use it properly. And to find out exactly how to do that, let’s take a look at this recent meta-analysis which ranked several different fat loss protocols from most to least effective. As expected, cardio alone with no changes to diet was the least effective method. But take a look at the most effective methods. Notice how they are all combinations of some form of exercise with a proper diet.

Think about how much easier it is to eat 500 calories less than it is to try to burn off 500 calories every day. I illustrated this in my last video where I ate a bunch of McDonald’s and figured out the hard way just how difficult it was to burn off.

So think of cardio not as a sole method you’ll use to lose fat but rather as a supplemental tool that you can stack on top of your diet to speed things up. But now that I’ve hopefully convinced you to start tracking and following a diet, how much cardio should you then add to this?

Expert Advice from Bodybuilders

Well, let’s start by asking the only people in the world who have truly mastered the art of controlling their diet while using cardio to get them into incredible shape: professional bodybuilders. First, I spoke to Alberto Nunez, an extremely knowledgeable coach and lifetime drug-free pro bodybuilder who’s known for getting into insane levels of leanness.

“I didn’t use cardio at all really. I just—I’d rather diet a little bit longer and rather eat less than have to go perform some other sort of exercise, especially exercise that I don’t necessarily enjoy. But this last prep was—it was nice. It was nice to actually do some cardio, and so I’m like, oh, I get to eat a little bit more because I am doing this cardio. I also feel that it helped with just some of the recovery aspects because, like, even though I know better, like, I’m going to just after training just be garbage and just like laying around.”

Daily Step Count

I also spoke with Lee, a natural bodybuilder just a few weeks out from his show. “I honestly think that we could probably get through this entire prep without cardio. The other alternative was, again, to not do cardio but then decrease calories further. But, you know, like the lower the calorie deficit, the less good essentially you’re gonna feel.”

So it turns out that by using either a longer or more aggressive diet, these guys didn’t really need cardio to get into crazy shape. But including it had its benefits. Now, what also surprised me was the importance they placed on their Daily Step Count and how they use it as part of their overall cardio plan.

“Our bodies are fantastic at surviving, and they will figure out ways to slow down the rate of loss. I first started noting this with my check-ins with my athletes. As they were getting leaner, their rooms just started to get messier. Like you could see like legit the fact that they weren’t doing much other than like going to work, going to the gym, and then just like couching it up. A lot of our actual modifications are going to come through diet, cardio, and the steps are just kind of there in place to make sure that you don’t slop around.”

Implementing Cardio

“I’m the type of person who would either be at home playing games or be at the gym. I was doing about like hardly any steps at all, so like 2,000 steps per day. We were just like, you need to move around more, and that way we can keep your food as high as possible. So we initially started with 10,000 steps per day. We lost about roughly 30 pounds until we started introducing cardio.”

Amount of Cardio Required

But now I wanted to find out on top of their daily steps, how much actual cardio is required to get to very low levels of body fat. “The smaller the athlete, the more cardio we will have to do, and it helps so they can eat a little bit more, which is obviously going to help with the mental component to some extent. And then also with women, they’re smaller systems, they tend to clear up a lot of the fatigue that cardio might add to the situation. I’m just like, wow, we’re doing like an hour each day, six days a week, and you’re still progressing with your training. Like that blows my mind.”

Alberto also emphasized how it depends on your lifestyle. “I’ve had people do nothing. Nothing. And usually, this has to do with the occupation. I mean, if they don’t move, they just get fired. Servers, personal trainers, labor-intensive jobs, things like that.”

But for most of his clients, here’s what he recommends: “7,000 steps on average, like just sit there. Like is there a baseline you have that set? I’d say most people on top of that to get to their goal—like we’re talking about like, you know, like pretty freaking lean. So roughly around like closing in on like 10, 11, 12 percent body fat for men could have like 10 percent to that or for women. Those are going to require like four or five days of cardio a week ranging anywhere between 30 to 45 minutes. There’s almost no exception.”

Lee’s Protocol

This seemed to line up with Lee’s Protocol as well. On top of 10,000 steps a day and lifting weights four times a week, he’s also doing 30 minutes of cardio five times a week. But remember, this isn’t just to get six-pack abs lean. We’re talking shredded. And they also don’t go from zero cardio to five times a week right away. They build up to it over time and only when they need it. Whenever fat loss is stalled and they’re not making progress, that’s typically when they decide whether or not they should add more cardio.

“Probably not a bad idea to ask them, okay, what would be the least invasive thing to you, like logically for the rest of your life? So I might consider cardio or I might just consider cutting calories. But yeah, like also like appetite. Maybe my appetite’s been like in check, so I’m like, all right, you know what, just slash those calories because that’s gonna be the most passive one.”

“At around six weeks out, at this point I was pretty hungry, so rather than decreasing calories further to increase weight loss, we decided to, well, let’s increase cardio so we burn more calories essentially.”

Types of Cardio

Now, as for the type of cardio they use, I found a common theme between both of them. “If you are going to use cardio, things with minimal impact, things that are just like a perpetual concentric, like an elliptical or a bike.”

“So we started doing cardio on the elliptical machine, and that’s just to kind of reduce as much fatigue as we can, especially since we’re still trying to maintain strength or even try to progress inside of training.”

Importance of Weight Training

Now, the reason they place such importance on their weight training isn’t just because they want to look as jacked as possible. As you diet, your body will need to burn off something for energy. It can choose from either muscle, fat, or a combination of both. So although lifting weights doesn’t burn as many calories as cardio does, it does give your body a strong reason to hang on to the muscle you’ve got and to burn off your fat for energy instead.

This is probably why in the meta-analysis I showed earlier, you may have noticed that combining diet with resistance training was one of the most effective fat loss methods, performing even better than combining diet with just cardio. So think of the Holy Trinity of fat loss as a combination of diet, lifting weights, with cardio on top of that to speed things up.

How Much Cardio to Aim For

Now, as for how much cardio per week you should aim for, what I’d recommend is just start with Alberto’s recommendation of walking 7,000 steps a day as a baseline in combination with your diet and weight training. This alone should already be enough for you to start losing fat. Once you’re consistent with that, you can add in some cardio sessions to get your heart going and just to speed up the process. Two to three 20-minute cardio sessions per week should be a good start.

And although Lee and Alberto recommended cycling or the elliptical, you have plenty of other options. I personally love variety, so some days I’ll do incline walking, some days I’ll do cycling, and sometimes I’ll go swimming. The key is to choose things you actually enjoy and can recover well from.

Now, from here, once your body adapts and you reach a stall in your progress, you can choose to either eat a little bit less or add a little bit more cardio or increase your steps to continue losing fat. And you basically repeat this process for as long as it takes you to reach your desired level of body fat.

Long-Term Success

Now, we did see on average how much cardio Alberto’s clients do towards the tail end of their diet, but remember, they’re getting very lean. So please don’t just follow that blindly. The amount of cardio you’ll end up needing will heavily depend on your goal, your body, and your lifestyle.

So you have your cardio plan, but I do have a word of caution. The last thing you want to do is start doing a bunch of cardio during your diet and then stop cold turkey as soon as it’s over. That’s the biggest mistake people make, and it’s actually when cardio becomes most important. Here to explain this is well-known fitness scientist and natural bodybuilder Dr. Eric Helms.

“So after a weight loss phase, most people unfortunately are going to regain at least a proportion of the weight that they lost. However, what most people do, which is a mistake, is they stop doing the exercise they were doing as part of the cutting phase. You don’t have to maintain all of the cardio you’re doing while cutting, but keeping a certain amount of activity going can prevent some of that weight regain from happening.”

Eric explained it seems to help regulate your hunger and while also slightly increase the number of daily calories you burn. “There’s a great systematic review that was recently published in 2019, and they found that doing just 150 minutes or more per week of activity generally—which of course could be cardio, but if you’re lifting weights, that counts as well—is sufficient to prevent weight regain. If you’re already getting weight lifting in that amount, then we need to look at, okay, well, what’s the maximum benefit I can get here? And some of the meta-analyses that look specifically at cardio, they seem to show that there are some benefits that are probably maximized around getting seven to nine thousand steps per day.”

Choosing Activities

This is why for Long-Term Success, it’s so important to choose activities you can actually stick to. Whether it’s watching a movie on the treadmill, playing a sport, or just going for walks to start out, find something you can do regularly to get you moving. Remember, cardio isn’t just something you should do during a diet, and you shouldn’t do it just for the fat loss benefits. Do it for your overall health and well-being.

And for a science-based program that shows you week by week exactly what to eat and what workouts to do to get you into the best shape of your life, just head over to builtwithscience.com and take our quiz to find what program is best for you and your body. Highly recommend giving this video a watch next for a super easy-to-make, budget-friendly meal plan for fat loss or give this video a watch next for a step-by-step walking plan for fat loss so you can start doing today.

Thanks so much for watching, and I’ll see you next time.

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