Do’s & Don’ts of Cardio & Fat Loss

by Dr. Jacob Wilson, Ph.D., CSCS*D

November 16, 2017


When I first got into bodybuilding I had this incredible preoccupation with being shredded beyond belief. I can remember my brother Gabriel Wilson and I headed to the gym to do up to 4 hours of cardio on some days! Was this efficacious? Is this unheard of? Was it crazy?! Not for people with extreme personalities like mine. If I want to excel in science I study 12 to 14 hours a day. If I wanted to be shredded I’d train 3 times a day. It’s just how I am. While being hardcore and dedicated certainly has merit there certainly is something to be said for working smarter and harder. With that said Id like to take a step in the right direction with this article and tell you what science says about cardio and fat loss. What we are specifically referring to is traditional cardio here. By that, I mean low to moderate intensity cardio that lasts at least 20 minutes or more in duration. Similar to many of my articles, I am going to do this in a questions and answer format.

Do I need Cardio to Lose Fat?


Surprisingly, you do not need cardio to lose fat. Although, as I will discuss, it may not only be more efficient, but more effective to add cardio to your program if your goal is getting shredded. A study by Dr. Ross and colleagues found that diet alone could increase fat loss. However, diet plus cardio led to more fat loss than diet alone (Ross et al., 2004). Additional research shows that fat loss in the stomach is actually far greater when you do cardio plus diet over diet by itself (You et al., 2006). It seems that the sympathetic nervous system which releases fat burning hormones like adrenaline and noradrenaline has a large presence in the abdominal region compared to the lower body region. If you want more information on fat loss targets, check this article on fat burners, which can mimic the effects of fat loss through supplements.

What are the Long Term Benefits of Cardio?


As you adapt to doing cardio over several weeks and months your ability to use fat improves both during and after exercise (Thompson et al., 2012). In addition, your relative intensity is much lower at a given speed (Thompson et al., 2012). This means that cycling at 12 miles an hour may be very hard when you are out of shape, but very easy when you are in shape. As such you can withstand greater speeds and burn more calories when trained than untrained. These are a few of the adaptations that you make when you perform low-intensity cardio. You will also improve insulin sensitivity, resting metabolic rate, and improve your cardiovascular health.

Can Cardio Cause Muscle Loss?


Cardio can cause muscle loss when done alone. In fact, if you look at marathon runners you will notice that they tend to be on the thinner side. Our research has shown combining cardio with weights causes more fat loss but also lowers your ability to gain muscle mass (Wilson et al., 2012). So, what are ways we can avoid losing muscle mass while doing traditional cardio? There are several ways listed below:

1. Cardio impacts only the muscles that are used. This means that if you do cardio for the legs it won’t hurt your upper body gains. So, doing cardio on an upper body day won’t hurt your gains in the upper body. However, training the lower body on the same day as cardio will hurt your gains. Therefore, separate cardio from legs by at least 24 to 48 hours.

2. The type of cardio you do also affects your gains. Our research shows that running causes more muscle damage and hurts gains in muscle more than cycling. Therefore, you should minimize running and try and use non-impact activities such as cycling or the elliptical.

3. Cardio done for more than 20-30 minutes impairs muscle gains more, which means I would recommend keeping your cardio short and intense.


In conclusion, if you want a shredded physique, cardio is a must. As I said before, you can get leaner by just dieting and training properly, but if you want single digit body fat, you are going to have to incorporate cardio. This is because cardio is an excellent tool to lose body fat in the mid-section. As with any training, you should periodize your cardio. Therefore, do not do too much steady state cardio for too long because it can be detrimental to your gains. I would never go over 30 minutes of low-intensity cardio more than four days per week. Start low and progress upward. Also, do not forget to use HIIT or advanced variables such as giant sets because these can also sky-rocket your metabolism and help with fat loss.