THE BODPOD – What it is and how to use the data to increase performance

Hey everyone!

I recently went to the Memorial Hermann Ironman Institute Human Performance Lab for a couple different tests that they offer. I actually used to live RIGHT NEXT DOOR, and when I did I had no idea how awesome this place was. I’ve been there a couple times now for different Trail Racing Over Texas events, and it’s so much more than a sports medicine clinic. Sure, you can get PT there, but you can also do strength and conditioning, consult with a sports dietitian (#dreamjob), and get alllll sorts of crazy tests to dial in your training. Basically, they cover all aspects of performance to make you a better athlete.

When I went in, I did a run lactate test and sat in the Bodpod with Kimberly Gandler, a biomechanist and exercise physiologist who is in charge of a lot of the testing and who also happens to be super awesome. This post is dedicated to the Bodpod, which looks like a mix between a personal space ship and a giant egg; but which is really a device to measure body composition.

Why body composition matters

For everyone: In clinical practice, we use weight as an indicator for disease risk (your BMI, or weight for height, is a simplistic measure that on a population-wide level can indicate risk for chronic diseases like atherosclerosis and type 2 diabetes). However, weight doesn’t tell the whole story: what that weight is made up of matters! More muscle will cause a person to weigh more, but does not carry the same disease risk that more fat does. Likewise, a person of a “healthy weight” who has little muscle but a bunch of fat can be at increased risk compared to others with similar BMI! Understanding the amount of fat that you have can help you understand your health much more than simply knowing your weight, we just can’t measure it as easily so it’s less frequently used.

For athletes: For endurance athletes like myself, weighing less makes you faster. Knowing how much body fat you have can help you determine whether it’s a good idea to lose a little bit of it in order to improve race times. On the other hand, it’s pretty common for athletes in certain sports to get too lean, which increases risk for a lot of really terrible things. Staying in a healthy range is crucial for long term success. For athletes in other types of sports, increasing lean body mass (aka muscle) is a huge goal in order to increase power, or perhaps simply for aesthetics if they’re a figure competitor. Having hard numbers is an objective way to determine if their eating and exercise routines are successful in achieving the goals they’ve set forth.

What to expect

The Bodpod takes almost no time at all – probably 20 minutes from walking in to leaving, with a detailed explanation of what the readout means. You have to go in fasting for at least two hours and wear as little as possible. For me, that meant spandex shorts and a sports bra. You’ll be given a hilarious cap to wear (see photo below), and you’ll be weighed on a scale connected to the device before sitting down inside it.


The Bodpod hinges open, and inside is a little seat that you sit on as still as possible, breathing normally. The door is closed, and the air pressure changes as the Bodpod takes measurements. The door is opened, and another measurement is taken, and you’re done!

How it works

The Bodpod uses air displacement to calculate body volume (aka how much air is in there without you in it, and how much air is in there without you in it). Underwater weighing is sometimes used to do this, but you can imagine that that process is much less pleasant. I for one would much rather sit in a giant spaceship than be dunked in a tank of water! The volume measure along with your weight can be used to calculate body density, which along with your height allows calculations for % fat, % fat free mass, a category grouping for your body fat percentage (either risky high body fat, excess fat, moderately lean, lean, ultra lean, or risky low body fat) abdominal gas, estimated resting metabolic rate (RMR, the calories your body burns if you were to sit in a chair all day and do absolutely nothing), and estimated total energy expenditure (TEE the calories your body burns if you were to go about your normal day without exercise).

How to use this information

Two things about the Bodpod’s readout are key for endurance athletes:

  • How much fat to you have? Is it on the high side and you could lose a little bit in order to get faster? Is it on the low side and you don’t have enough to draw from safely for long sustained efforts? It’s true that running with less weight is faster – just try jogging with a weight vest and this will become very apparent. So knowing whether you have a little you could lose can be helpful if you’re looking to be as fast as possible. HOWEVER, our fat also works to our advantage in a lot of ways. We use that as fuel during long sub-maximal efforts, and if your fat percentage is too low you’re more likely to break down tissue you don’t want to break down for energy (muscle), plus you’re at greater risk for getting sick/messing up your hormones/amenorrhea/low bone density/low T/all sorts of things you don’t want to happen. It’s all about balance, people!
  • How many calories do you need to function? The RMR and TEE do not take into consideration the calories burned during exercise, so the TEE is what you absolutely positively need to eat on rest days in order to maintain weight and recover well. You can also use these numbers to guide safe weight loss if desired.

Using the Bodpod for performance benefit

For athletes losing weight: While counting calories obsessively is a bit suffocating, in the event you decide to lose some body fat it can be helpful to use the TEE number as a guideline on rest days or easy days. and in combination with My Fitness Pal, you can use these numbers to figure out what a moderate (like 250cal/day) deficit looks like in terms of food. A good recommendation would be to track your food for a couple days, compare it to your TEE, and look at where you can “cut the crap” – aka those random little things you ate when you weren’t hungry or the poor (high fat, high sugar) choices you made “because you can”. Usually that is enough to cut enough calories to lose 0.5-1lb/week. If you’re training seriously, I wouldn’t recommend trying to lose more than that.

For athletes maintaining weight and maximizing performance: It can be hard, especially during periods of high training volume, to maintain your weight. If you know how many calories your body needs and can estimate what you’re burning during exercise, you can dial in your eating in order to support your training. A key point is to make sure that you’re following up workouts with protein soon after, and getting ~20-30g of protein per meal and spacing your protein out throughout the day. Your body can really only use this much at a time for muscle synthesis, any extra is used as just generic calories (which isn’t a bad thing) but with high training volume it’s imperative to focus on maintaining muscle mass or else you’re gonna lose some! If you have a hard time stomaching food after a hard workout and this is negatively impacting your caloric intake, try liquids – chocolate milk, smoothies, and protein shakes all go down pretty easily. Additionally, if you’re doing doubles and experience appetite suppression after your workouts, switching to one-a-days could be helpful.

Using the Bodpod for general health

I’ve been talking about this like everyone here is an endurance athlete, but this test can be helpful for people who aren’t training for anything. Body fat percentage is a key indicator for disease risk, and working on decreasing body fat and increasing lean mass is a really great way to improve your overall health. In order to achieve this, a calorie deficit of 500-1000/day (which includes energy expended during exercise) in order to lose 1-2lb/week along with a rigorous strength training regimen supported by protein in 20-30g “doses” at meals will allow you to build muscle while losing weight. MUCH easier said than done, but the Bodpod test will help you to get a sense of where you’re at, allow you to refine calorie goals, and if you take multiple measures over time you can track your progress! The tough thing with using weight as the only indicator of progress is that you can’t see how your body composition is shifting. Even a very slow weight loss with an increasing percentage of lean body mass is a gigantic benefit!

What I learned and what I’ll do with the information

My personal results showed that I’m on the lower end of the “moderately lean” category. Clearly, it could be lower, or rather my % lean mass could be higher! The thing about this is that I can’t build lean mass if I don’t hit the gym, which is something I’ve been really bad about doing lately. Ever since I started school on top of work and running pretty seriously, it’s been difficult to get to the gym with any sort of consistency. I’ve got some free weights at home that I can use, but even those aren’t getting as much action as they should. I definitely feel guilt about this sometimes, since lifting makes me feel sooo good and strong and powerful and I know I need to do it; having the numbers to show that my muscle mass could be improved gives me a little kick in the butt. My plan to improve my lean mass is to focus on strength training at least two days/week (winnable goals, people) over the summer while I take my mileage down a bit and let myself recover from a big fall/winter/spring.

I also learned that it really doesn’t take too many calories to run my body! This confirms that in times of decreased activity, I need to be really cognizant of my intake. I’ve been running really consistently for the past year (knock on wood!) so my eating habits would have to make a pretty big shift if I had to stop for some reason – the calories burned exercising almost double my daily calorie requirement. There are periods where I do this, and my eating really doesn’t change all that much: less carbohydrate because I don’t need to power as much exercise, and cutting the crap as mentioned above does the trick. Since I’ve cultivated a strong love of eating healthfully, tons of veggies, lean protein, and some complex carbohydrate is really no different than usual. The key is to listen to hunger and fullness cues rather than eating out of habit, and that’s something that everyone should strive to do on a daily basis.

Overall, the Bodpod was super cool! This information is really helpful, and I plan to go back to recheck how everything is lookin’ in the future after I work on building muscle or in the lead up to a big race.

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