Methods for Estimating Adaptive TDEE
Part of “Nutrition (Sports Science)”
Abstract
Nutrition plays a very big role in both (physical and mental) performance during physical exercise as well as recovery afterward. Optimizing this process can be done via e.g. estimating TDEE and using that to further estimate recommended caloric and carbohydrate intake as well as their nutrient timings.
I recommend the following meta-analysis on the impact and timing of nutrition on physical performance and recovery:
Content
- Calculating TDEE
- Simple method using an online calculator
- A simple yet more detailed (and fast) method of adaptively estimating daily caloric needs
- A more advanced method accounting for individual RMR (and therefore TDEE) + impact of muscle mass
Calculating TDEE
Simple
The most simplest way I can think of is to just use an online calculator using the Mifflin-St Jeor equation, as this one is found to be the most accurate (source: Comparison of Predictive Equations for Resting Metabolic Rate in Healthy Nonobese and Obese Adults: A Systematic Review — Journal of the American Dietetic Association (jandonline.org)). E.g., this online calculator:
The following source contains nice lists of different examples considering Physical Activity Level (PAL):
Simple-Detailed
Another simple but more detailed way I personally like to start with, is to simply put Physical Activity Level at whatever you think you will perform on a specific day and put the calories you burn from exercise on top of that.
A possible advantages of this method compared to the simplest method mentioned above is that you are now adaptively fueling your workouts better as well as its recovery afterward.
An extreme example of this would be doing the training load / distance / time you do currently weekly, but now all of it 1 day per week. The caloric requirement to fuel and recover from that should then, most of it (with a smaller percentage the day before and after), be allocated toward that specific training day (i.e. nutrient timing).
When it comes to nutrient intake for athletes and active individuals, there exists a hierarchy of needs. If we look at it like baking a cake, the training stimulus and the total daily intake form the cake itself. The timing of nutrient intake is more like the frosting, which requires the foundation of the cake to do its job. Finally, the more advanced concepts such as nutrient periodization and CHO-restricted training are the decorations on the cake. Most importantly, proper feeding around training, despite questions of magnitude of benefit, is never detrimental.
Source: [PDF] Nutrient Timing: A Garage Door of Opportunity? | Semantic Scholar
To give an example of my own:
Sex: Male
Age: 23
Height: 175 cm
Weight: 65.4 kg
PAL: Sedentary
This would give a BMR of 1638 kcal/day and a TDEE of 1965.3 kcal/day. Now, what I simply do if I for example cycle for 2 hours at 155 watt that day, is to add the caloric requirement of that workout on top of TDEE i.e.:
- 1965.3 kcal + 1067.9 kcal = 3033.2 kcal
→ (155 watts (= 155 J/s) · (2 hours · 60 minutes · 60 seconds) / 25% / 4.18 = 1067.9E3 calories = 1067.9 kcal)
→ 25% = Gross Metabolic Effiency (see: kJ to Calories Conversion: How many calories do I burn cycling? (trainerroad.com))
→ 1 cal ≈ 4.18 J
→ Tip: I personally prefer using GME=25% when one of my goals is fat loss
Advanced
A more accurate way to calculate TDEE would be via e.g. an Adaptive TDEE Calculator app like the following:
The problem with such an app could be that it doesn’t account for daily variable changes in calories burned from activities (because you can’t put those in the app). A possible workaround to this, is by tracking your average calories burned from exercise and simply do “Adaptive TDEE − Average Calories Burned from Exercise” and use that as your RMR (and finally adaptively add whatever work you will perform a specific day on top of that).
Another way, thus, is to create a spreadsheet yourself. The formula is simple:
Estimated RMR = Average Consumed Calories − Average Calories Burned from Exercise − Average Grams of (Fat) Gain/Loss converted into Calories
→ 1 g of fat = 9 calories
This formula sadly doesn’t account for e.g. non-exercise activity thermogenesis (NEAT), because it could be difficult to accurately estimate that in a variable manner, daily, but you could simply use the number an online calculator uses (i.e. the difference between TDEE and BMR → in my case it would be 1965.3 (sedentary) − 1638 = 327.3 calories, see above).
My own personal spreadsheet (which contains formulas that can be readily copied): https://docs.google.com/spreadsheets/d/1j-D0HnTzRd4hIKvhOWqqj73jt74d61kq0M6puUJcNF8/edit?usp=sharing
In my case, it estimates my RMR at approximately 1606.3 calories per day (which is close to what the online calculator mentions as well and becomes more accurate over time), of which I have to add 327.3 calories on top of that to account for e.g. NEAT, and at the end I put the calories burned from exercise to estimate what I should be eating that day (given the above example of 2 hours of cycling at 155 watts, it would be 1606.3 + 327.3 + 1067.9 = 3001.5 calories.
RMR differs from basal metabolic rate (BMR) because BMR measurements must meet total physiological equilibrium whereas RMR conditions of measurement can be altered and defined by the contextual limitations. Therefore, BMR is measured in the elusive “perfect” steady state, whereas RMR measurement is more accessible and thus, represents most, if not all measurements or estimates of daily energy expenditure.[1]
Metrics
When using an application like Intervals.icu, the 3 main metrics I use to track the aforementioned are Weight (As is), kcal Consumed (Weekly Average), and Calories (Weekly Average):
Impact of muscle mass on TDEE
Finally, to add on to the advanced method, we can also try and account for how much muscle mass increases TDEE.
I recommend reading the following article by Stronger By Science as well as using their online calculator below:
In my case, I am extremely active and therefore each kg of muscle increases my TDEE by approximately 31 calories.
You would, however, need to accurately estimate your lean muscle mass (e.g. via a DXA-scan).
