Complete Cardio Part 3: Frequency, Timing & Fasted Cardio

One question that gets asked a lot by weight-training enthusiasts is: What’s the minimal amount of cardio I need to do to see fat-loss results? Of course, this is usually asked by those who think of cardio as only the slow and steady type done on a treadmill or stationary bike. Most people who enjoy lifting tend to loathe cardio. But once they realize that cardio can be done with weights, HIIT style, they end up asking: How much is too much?

There’s evidence both from research and anecdotal reports that the minimum amount of cardio you should do each week is three to four workouts.

One study put 90 male and female subjects on an eight-week program that consisted of doing cardio for 30 minutes straight. They divided the subjects into groups based on how often they exercised each week. One group served as a control and did no exercise; a second group did the cardio workout less than twice a week; a third group did the workouts two to three times per week, and the fourth group did cardio four or more times per week.

They discovered that at the end of the eight weeks, only the last group performing cardio four or more times per week lost a decent amount of body fat (almost 15 pounds of it). Of course, the subjects weren’t weight training in addition to doing cardio and they also weren’t doing HIIT, so it’s hard to say from this study precisely how many days of cardio you need in addition to weight training. Anecdotal reports suggest a minimum of three HIIT cardio sessions per week in addition to weight training. But obviously, the more you do each week the greater the expected fat loss. In fact, you can do seven days of cardio per week if you prefer. And that can be seven days of HIIT, mind you.

You may be worried that doing HIIT that often will lead to overtraining. However, as long as you’re switching up the exercise choices, you can do HIIT every day of the week. After all, it’s typically done for only 15-30 minutes -- and that’s not even total exercise time. One study in athletes found that those using HIIT every day experienced no decrement in performance. So much for overtraining.

Cardio Timing
Whether you do your cardio immediately before you lift weights, immediately after, during weight workouts (such as cardioacceleration, discussed below) or in an altogether different training session matters little to the effect it will have on fat loss. The most critical aspect of scheduling your cardio is when you’ll be most consistent doing it.

If you tend to skip cardio when you leave it to after your weight workout, then consider doing it before or during your weight-training session or at a completely different time or day. There are two options when it comes to doing cardio during your weight-training workouts.

Option one is to do cardioacceleration, which involves a 30-90-second bout of high-intensity cardio in between every lifting set. (I’ll cover cardioacceleration in greater depth in the next installment of my Complete Cardio series.) Or you can do a bout of HIIT in between muscle groups. For example, if you train back, biceps and calves in one workout, you could do 10 minutes of HIIT in between back and biceps, in between biceps and calves and after calves for a total of 30 minutes of HIIT. Several studies have reported that breaking up your cardio into several smaller sessions allows you to burn more calories during the workout as well as more total calories and more calories from fat after the workout is over. This has also been shown to allow subjects to lose significantly more total fat over a prolonged period.

Fasted Cardio
Another misconception about cardio is that the best time to do it is first thing in the morning on an empty stomach. Research does, in fact, show that you burn more total fat when you do cardio in a fasted state; some research shows that you can burn 20% more fat when you do cardio in the morning on an empty stomach.

However, as mentioned above, how many calories and how many calories you burn from fat during the exercise shouldn’t be the major focus. Research suggests that when you burn carbs during exercise, you burn more fat after the exercise is over, and when you burn more fat during exercise you burn more carbohydrates afterward. In other words, it’s more about the total amount of calories and fat you burn throughout the day, not just during exercises. Research also suggests that whether you exercises first thing in the morning fasted or fed, you end up burning the same amount of calories total throughout the day.

Generally speaking, your best bet is not to worry about doing cardio first thing in the morning or fasted. If doing cardio first thing in the morning is best for your schedule, then by all means do it then. But it’s advisable to have at least a protein shake (like Pro JYM), if not both a protein shake and some carbs (such as fruit), before the workout. If you’re trying to limit carb intake, you may want to avoid the carbs until after the workout is over.

And of course, to maximize intensity during the workout and promote long-term gains in size, strength and fat-burning, I suggest taking Pre JYM before all HIIT workouts. Afterwards, Pro JYM and Post JYM will help ensure adequate muscle recovery so you’re able to train hard on subsequent days.

With all that being said, there’s one time when fasted cardio may be a strategy you want to employ. Anecdotally, I’ve found that fasted cardio can work well for men with body fat that is in the low single digits (somewhere around 5%-6% body fat) or females with body fat in the low teens (somewhere around 13%-14% body fat) who have one stubborn area of unwanted body fat.

Many males, especially older males, tend to hold fat on the lower back and obliques. Many females tend to hold fat on the hips and thighs. And no matter how hard they train and diet, this fat holds on for dear life. Over the years, I have found that once they’ve dropped the majority of the subcutaneous fat on the rest of the body, fasted cardio does seem to work well to rid that last bit of fat. Although there’s no direct data to look at, it may be that when a person is so low in body fat and only has fat on certain stubborn areas, exercising in a fasted state may be the spark that those resistant fat cells need to release that stored fat so that it can be burned away for good.

But if you’re a male at about 8% body fat or more, or a female at about 16% or more, then fasted cardio is likely not going to make much of a difference in your fat-loss efforts. Do cardio, preferably some form of HIIT, consume a clean diet and the fat will come off.

In the next installment of this series, I’ll go more in depth on two of my favorite ways to employ HIIT in my programs: cardioacceleration and Tabata intervals. 

Part 1 HIIT vs. Steady State

Part 2 HIIT Programming

Part 5 Power HIIT

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