11/03/2026
Might have to rethink my laptop day snacks!
Most people track calories as a weight loss tool. Very few think about them as a performance input.
Using a CPET machine to measure my actual oxygen and carbon dioxide exchange, the most accurate way to assess metabolic rate outside of a clinical setting, I can see my body burns around 2956 calories on a day of seated, focused work. My BMR alone is 2230. That means just being a functioning human with a cognitively demanding job burns significantly more than most standard dietary advice accounts for.
Add a walk, a training session, or a full day of travel and meetings, and total daily expenditure can climb to 3800, 4000, or beyond without breaking a sweat in the traditional sense.
The question then is not how little can I eat, but how precisely can I match my intake to what my body actually needs today.
For anyone running a business or coaching clients, energy availability is a direct input into decision quality. The prefrontal cortex, the part of the brain responsible for planning, risk assessment, and emotional regulation, is metabolically expensive. When you are under-fuelled relative to your actual output, you are not operating at full capacity. You are slower to process, quicker to react emotionally, and less able to think several moves ahead.
The goal is not a number on a scale. It is showing up to the work with the mental horsepower to make good calls, lead well, and solve hard problems. That requires fuelling with intention, not just restraint.
Know your numbers. Match your intake to your output. Perform accordingly.
