Gym Geek’s adaptive TDEE spreadsheet uses a statistical model to create a more accurate estimate of your TDEE. Using your own calorie and bodyweight data, our sheet automatically adjusts your TDEE up and down to produce a unique and accurate result for you. With enough data, adaptive TDEE can be more accurate than the TDEE estimated by formulas like Mifflin-St Jeor.
What is TDEE?
TDEE, or total daily energy expenditure, is the number of calories your body burns each day. This includes your basal metabolic rate (BMR), the calories you burn when digesting food and also the additional calories you burn through physical activity like exercise.
TDEE is often called your “maintenance calories”, since if you eat exactly that number of calories you will neither lose or gain weight. Understanding your TDEE is crucial to weight management, since the key to losing weight is eating a calorie deficit relative to your TDEE; and the key to gaining weight is eating more calories relative to your TDEE.
Most calorie tracking apps and calorie calculators use an estimate of your TDEE. The most popular way of estimating your TDEE is with the Mifflin-St Jeor equation. This equation was produced by a statistical study that looked at representative populations, measuring their BMR and crunching the data to build an accurate formula.
The 1990 study behind Mifflin-St Jeor looked at 498 people across both genders, all age groups and normal weight and obese persons. The study introduced a formula based on a person’s weight, height, age and gender.
TDEE formulas can be inaccurate
Although TDEE formulas are fairly accurate for most people, it’s generally recognized that the estimates can be 10-15% off for a substantial number of people. A smaller number of people may have TDEEs much larger or smaller than that suggested by the estimates.
The formulas are based on statistical models and create an estimate based solely on a person’s age, gender, height and current weight. But a person’s TDEE can also be affected by things that can’t easily be measured, for example:
- Muscle mass – Muscle is more “metabolically active” than fat tissue. That means people with more muscle mass have higher basal metabolic rates and TDEEs compared to those who have a high body fat percentage.
- Genetics – A person’s genetics is known to affect TDEE. This is something that can’t be measured, so formulas like Mifflin-St Jeor effectively “average out” across all groups of people.
- Hormones – Many kinds of hormones have an impact on your body’s metabolism. Every person has slightly different levels of hormones, which can impact your metabolic rate. Conditions like hypothyroidism or hyperthyroidism can substantially decrease or increase a person’s TDEE.
- Diet – A high protein diet is associated with higher TDEEs. This is because digesting proteins requires more energy than digesting carbs or fats. This “thermic effect” of digestion, as it’s known, typically accounts for 10% of your daily calorie burn.
In practice, it’s not important to understand all of the factors that affect TDEE. But, with any weight goal, it’s important to accurately track your calories and regularly review your progress. If you are losing weight more slowly than expected, your TDEE might be lower than you initially calculated. And if you are losing weight faster than expected, your TDEE might need to be adjusted upwards.
What is adaptive TDEE?
Adaptive TDEE is a range of methods that use your own data to produce a more accurate estimate of your TDEE. Most TDEE algorithms are based on your calorie intake and bodyweight data over an extended period of time. They crunch this data to figure out a personalized and accurate number for each individual.
There are two main types of adaptive TDEE – first principles and statistical models.
Adaptive TDEE from first principles
Most adaptive TDEE spreadsheets that you find on Reddit and other communities calculate your TDEE “from first principles”. This means they look only at the number of calories you’ve eaten and how much weight you’ve lost or gained over an extended period of time.
Using this information, it’s possible to work out a precise number for each person. However, with only a small amount of data, this number has a wide error range. That means it’s not very useful unless you already have lots of data from the past.
To get an accurate estimate with this method, you’ll need at least a few months worth of data. If you’re only just starting to lose or gain weight, you might not have this data yet, which makes this approach somewhat limiting.
Adaptive TDEE with statistical modelling
A more advanced version of adaptive TDEE uses some clever statistics to combine the initial TDEE estimate with your own data. This approach produces a fairly accurate estimate, even with just one week’s worth of data.
To begin with, the algorithm calculates your TDEE based on the Mifflin-St Jeor equation. As we said above, this is within 10-15% of your true TDEE for most people. As you collect more of your own calorie and bodyweight data, the adaptive TDEE estimate adjusts up or down over time.
The more data you add, the more accurate the estimate becomes. The benefit of this approach is you get an estimate immediately, and you’ll only see gradual adjustments up and down.
Gym Geek’s adaptive TDEE spreadsheet
Gym Geek’s adaptive TDEE spreadsheet uses a statistical model to estimate your TDEE. We’ve made it as simple as possible to enter your data and get an estimate of your TDEE. In the spreadsheet, there are two columns – one for your calorie intake each day, and another for your recorded weight.
Here’s how to use the spreadsheet:
- First open the Google sheet here.
- Copy this sheet by clicking “File” and “Make a copy”.
- Since the sheet makes an API call to Gym Geek (for the statistical calculation), you may see a warning that says “Warning: Some formulas are trying to send and receive data from external parties.”. Click “Allow Access”.
- Select your height, age, gender and activity level from the dropdowns. See why below.
- Clear the sample data from the “Calories”, “Weight (kg)” and “Weight (lbs)” columns.
- For each day, record the number of calories you ate on that day.
- Record your weight in the “kg” or “lbs” column at least weekly, but preferably daily.
Why does the spreadsheet need my activity level?
It may seem counterintuitive to enter your height, age, gender and activity level into the spreadsheet. After all, adaptive TDEE is supposed to calculate your TDEE based on your own data, not from a declared values that plug into a formula.
However, unlike other spreadsheets, our spreadsheet combines the TDEE estimate from the Mifflin-St Jeor formula with your own calorie and bodyweight data. To produce this initial estimate, we need to know a few details, including your activity level.
With just one week of data, your declared activity level will have a large impact on your TDEE. This is because our algorithm will put more weight on the estimate rather than your own data.
Over time, particularly after 1-2 months, the impact of the initial estimate becomes less and less. With more data, the Mifflin-St Jeor has much less influence and your own data will be the main factor in the results.
References
Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American journal of clinical nutrition, 51(2), 241-247.
