Weight loss with CrossFit - Part 1

Among all the motivations to start CrossFit, losing weight is probably the most common one. This is a mini-series about weight loss in CrossFit. Today's question to answer: Is CrossFit the right sport to achieve weight loss goals?


How weight loss works: The calorie balance

I am assuming it is common sense by now, but I don't mind repeating it:

If you lose or gain weight is a question of the calorie balance: If you burn more calories (in other words: energy) than you eat, you will lose weight - and the other way around.

This, to be clear, only applies for a healthy human with no conditions like thyroid problems or dysfunction within the fat metabolism.

Being aware of this very simple mechanism, we can think about the two sides of the calorie balance - the intake and the output. The intake is the nutrition related part of the weight loss, and - without giving to much away - the more important one. 

But for now, let's stick with the calorie burning thing.


CrossFit influences the calorie output

A CrossFit training session burns calories. It can therefore contribute to a higher output and brings us closer to the negative calorie balance. 

But in that context, there is this one important question we have been asked many times before: How many calories do I burn within a CrossFit session?

And here is the unsatisfactory answer: It depends. Of course, on the WOD - was it a Tabata with air squats, was it a 30 minute Hero with running, heavy weightlifting and muscle ups? Was it hot or did you stay in the aircon? Did you go all out? And also: What is your fitness level? How old are you? How heavy? What is your gender?

Calories burned in a WOD might range from only a hundred or so to several hundreds, close to a thousand even. We have no accurate measurement systems, at least not in a non-professional environment. I know many people try around with wearables like the FitBit or so, but that can only give you an idea. Do not use it as a justification to stuff your face after each session.

Especially if you are new to CrossFit and weightlifting, you might not be able yet to train with this high intensity that actually leads to a high calorie burn. Also, if you are new to weightlifting, you will spend the first few months to work on your technique and neuromuscular adaption, so you will not reach challenging weights that also lead to an intense training with high energy output.

To cut a long story short: Especially beginner shouldn't over-estimate the calories burned in a one-hour training session. It is still more than some biceps curls and a 20-minute walk on the treadmill in a globo gym though. But stay conservative with your estimate.


But CrossFit influences the calorie output also in 2 other ways:

  1. A WOD leads to the EPOC, also known as the "Excess post exercise oxygen consumption" or afterburn. It says that after an intense training, the body burns more energy even in a calm state. Studies found duration from a few hours up to one day and amounts from a few calories up to several hundreds. Again: We can only guess. But the fact that you sometimes get sweaty again right away after the shower, or the warm feeling you have in the hours after exercising, are an evidence that the EPOC exists. 
  2. More muscle mass means more energy consumption 24/7. Muscles are a luxury thing and not easy to maintain for the body - that's why they are the first thing you lose when in starvation mode. More lean body mass (high muscle and low body fat percentage) means a more active metabolism - but be aware that this effect is a minor and only really significant for a bodybuilder from the open weight class who can't scratch his back anymore.


So - is CrossFit not the right sport for weight loss?

What I have written so far doesn't sound very optimistic. Should you rather look out for another sport to lose weight?

I am against lying into people's face like many CrossFit gyms do, telling prospects that this hardcore training is the guarantee for weight loss, no matter how crappy your diet might be. If you are only looking for a high calorie burn, rather do ultra-distance running. Also takes away the stress of learning the muscle up and buying ten different shoes and gloves.

I still believe CrossFit is a great sport to lose weight for a simple reason: It is fun and pure! It will make you stick to a workout routine, just staying active and developing a better, closer relationship to your body. And with that - very important! - you will eat healthier and in more reasonable amounts just by instinct.