Can You Be Fat AND Fit?

The short answer is “yes“.

And as for what that means for your heart and/or all-cause mortality risk: it’s just as good as being fit at a smaller size, and furthermore, it’s better than being less fit at a smaller size.

Here’s the longer answer:

The science

A research team did a systematic review looking at multiple large cohort studies examining the associations between:

• Cardiorespiratory fitness and cardiovascular disease risk
• Cardiorespiratory fitness and all-cause mortality
• BMI and cardiovascular disease risk
• BMI and all-cause mortality

However, they also took this further, and tabulated the data such that they could also establish the cardiovascular disease mortality risk and all-cause mortality risk of:

1. Unfit people with “normal” BMI
2. Unfit people with “overweight” BMI
3. Unfit people with “obese” BMI
4. Fit people with “normal” BMI
5. Fit people with “overweight” BMI
6. Fit people with “obese” BMI

Before we move on, let’s note for the record that BMI is a woeful system in any case, for enough reasons to fill a whole article:

When BMI Doesn’t Measure Up

Now, with that in mind, let’s get to the results:

What they found

For cardiovascular disease mortality risk of unfit people specifically, compared to fit people of “normal” BMI:

• Unfit people with “normal” BMI: 2.04x higher risk.
• Unfit people with “overweight” BMI: 2.58x higher risk.
• Unfit people with “obese” BMI: 3.35x higher risk

So here we can see that if you are unfit, then being heavier will indeed increase your CVD mortality risk.

For all-cause mortality risk of unfit people specifically, compared to fit people of “normal” BMI:

• Unfit people with “normal” BMI: 1.92x higher risk.
• Unfit people with “overweight” BMI: 1.82x higher risk.
• Unfit people with “obese” BMI: 2.04x higher risk

This time we see that if you are unfit, then being heavier or lighter than “overweight” will increase your all-cause mortality risk.

So, what about if you are fit? Then being heavier or lighter made no significant difference to either CVD mortality risk or all-cause mortality risk.

Fit individuals, regardless of weight category (normal, overweight, or obese), had significantly lower mortality risks compared to unfit individuals in any weight category.

Note: not just “compared to unfit individuals in their weight category”, but compared to unfit individuals in any weight category.

In other words, if you are obese and have good cardiorespiratory fitness, you will (on average) live longer than an unfit person with “normal” BMI.

You can find the paper itself here, if you want to examine the data and/or method:

Cardiorespiratory fitness, body mass index and mortality: a systematic review and meta-analysis

Ok, so how do I improve the kind of fitness that they measured?

They based their cardiorespiratory fitness on VO₂ Max, which scientific consensus holds to be a good measure of how efficiently your body can use oxygen—thus depending on your heart and lungs being healthy.

If you use a fitness tracker that tracks your exercise and your heart rate, it will estimate your VO₂ Max for you—to truly measure the VO₂ Max itself directly, you’ll need a lot more equipment; basically, access to a lab that tests this. But the estimates are fairly accurate, and so good enough for most personal purposes that aren’t hard-science research.

Next, you’ll want to do this:

53 Studies Later: The Best Way to Improve VO2 Max

Take care!