Are There Negative Side Effects of Doing Too Much Cardio?

Aug 30, 2021 mindpump

The hardest conversations I have with my clients trying to lose weight is telling them to back OFF cardio. Yup. I get clients all the time saying they can’t lose weight. They claim they are eating 1,000 calories and doing an hour of cardio a day or tons of HIIT training. How can this be? 

Believe it or not, more cardio isn’t better, and there is a limit to how much cardio you can do before it potentially works against you.

The Downsides of Doing Too Much Cardio

No one really gives a guideline on cardio. We’re told how often we should workout, but no one really talks about doing too MUCH cardio.

Muscle Loss – One of the biggest things to realize is cardio isn’t a strong enough stimulus for muscle growth or muscle retention. Why is this important? Even if adding muscle isn’t your goal, when you diet down I’m sure you’d like to have a more defined, and somewhat muscular physique after all that dieting right? If all you do is cardio, you just become a smaller version of yourself. Muscle is calorically expensive to have, therefore, your body would rather burn through muscle over fat.

Recovery – As mentioned before, people tend to overdo it. It attracts the types of personality that like more and more intensity. They are usually lifting 3-4 times a week, and doing 45-50 minutes of HIIT 4-5 days a week. They are also most likely not eating enough, or getting enough sleep to recover from this heavy workload.

Your body is built for survival. It doesn’t know you want to lose weight so it just interprets your diet as starving yourself. It will choose whatever allows you to stay alive most efficiently. This means holding onto fat as long as possible. Fat is a valuable energy source, so the last thing your body wants to do when it’s starving is sacrifice too much body fat in a row.


I’m not writing this to demonize cardio and its benefits. Ultimately you should stick with the routine you enjoy the most. You should also spend the most time receiving a stimulus from the activity you want to improve the most. If adding muscle is your goal, then more of your days should be spent lifting weights and not doing cardio (2-3 days is okay). If you are getting ready for a marathon, then you will probably be spending most of your days running and only 1-2 days lifting weights.

General Guidelines

If muscle building is the goal then I recommend 2-3 full body workouts. This will allow you to stimulate your muscles frequently and send the optimal muscle building signal to grow. Try to keep your cardio to 2-3 days a week so that you are still receiving the health and longevity benefits, without interfering too much with the muscle building signal. They can be all steady state, HIIT, or a mix of both. You can also increase your NEAT activity instead of dedicating more time at the gym. Try hitting 10,000 steps a day, and increasing up or down depending on your goals. If you are shooting for fat loss, try increasing your steps by 1,000-2,000 if you find you aren’t consistently losing 1-2lbs a week.

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