Here’s a problem I come across frequently as a trainer. A client or friend comes to me saying they can’t seem to lose weight. When I ask them what they are doing it’s usually some phrasing of “I cut out all carbs and do cardio 5-6 days a week for 45-60 minutes”.
This is a problem. You need to stop doing cardio…..at least for now.
Your Metabolism Adapts
The question on your mind for this client is probably “Why aren’t they losing weight?” After all, that's a lot of output, and very little input. Dieting is being in a caloric deficit and that IS a deficit isn’t it? Correct….until it’s not.
You see your body is VERY adaptive. It’s built for survival. Hell, even survival aside, it’s a VERY efficient machine. When we start implementing cardio we burn a lot of calories in each session initially. Yes, partially because doing exercise and moving expends calories, but also because you are presumably providing an exertive stimulus your body wasn’t ready for. For those first couple weeks, you see the weight dropping off so you think the cardio is doing its job and it is. But it’s MOSTLY because your body is INEFFICIENTLY responding to a stimulus it’s not used to. In other words, you're burning a lot of calories trying to complete this task because it’s tough for your body to process through (after all you hadn’t been doing any cardio before the diet).
But as the weeks go on, each week your body (just like we see with any sport or physical skill we get better at), improves to burn less and less calories each time. When you’ve hit that plateau where you’ve been doing the same thing yet achieving subpar results, your metabolism has optimized the excess caloric waste it took to first take on that skill. As you get better at running it slows your heart rate down, so that you can achieve that same amount of work at a better pace (hence why marathon runners have such lower heart rates, and why that same run can feel easy over time).
This is great for performance, but if the goal is dieting, this isn’t ideal cause now not only are we not burning the calories we want to create a deficit, but that means we would have to include even MORE cardio to get back to that caloric burn we were AT. Sounds exhausting. Add on TOP of that you ate less calories, and your metabolism is now slowing DOWN your caloric burn to match the input of calories you are taking in. If it senses over a long enough timeline that you are only taking 900 calories in, it doesn’t know you are doing that on purpose to look lean. It thinks you are starving and thus slows down it’s processes to match. Which means on TOP of adding MORE cardio, you now have to eat even LESS food to once again create a further deficit. See the dark road we are entering?
Recovery
There’s also the case of recovery. If you’ve now decided to stay on the diet (of a heavy deficit), and have added those 5-6 days of cardio (from an initial say 2-3 days) to make up the extra caloric burn, you are potentially overworking your body. It simply doesn’t have enough food coming in to repair properly. And that’s just assuming you are doing steady state jogging.
If you are also throwing HIIT intervals or higher intensity sprints overall, you are now adding extra volume of stress on the muscles (that you should be wanting to retain), without the calories to hold onto it. The only way to make sure you don’t lose that muscle is to either bring your calories up, or add resistance training 2-3 days a week to send a progressive load stimulus on the muscles which signal the body it has a reason to keep the muscle.
As far as going for a jog goes, that’s added mileage you are placing on the joints further working you down. It’s a recipe for disaster.
So What’s the Solution?
I don’t mean to demonize cardio here. I’m simply making you aware of how to BEST utilize it to preserve your muscle and sanity.
Cardio For Performance/Enjoyment - if this is the reason you are doing cardio then by all means keep doing it. You enjoy it, or maybe you are getting ready for a race. However if that’s the case, make SURE your calories are high enough to compensate for the energy you are burning through after these workouts. Give your body the proper fuel to heal before your next workout.
Cardio For Dieting - If you are adding cardio simply as a tool for weight loss, LESS IS MORE. Don’t START with cardio, let it be your final weapon (because it adapts so quickly). First, subtract 20-25% of your calories off your maintenance and start there. That should create enough of a deficit in itself to kickstart the weight loss. As mentioned before, the body will eventually adapt, but at least now we still have more tools at our disposal. When you hit the first plateau, either subtract another 200-300 calories, add 1-2 days of a 20-25 minute jog, or find other ways to increase your expenditure like NEAT. Take a 10 minute walk after each meal to hit that same caloric burn as a jogging session without the added joint stress. It also makes it easier to fit into your day and create a sustainable habit.
