Initial data on your nutrient requirements is taken from the source we mentioned before. However, as I see it, the values from those tables represent the base-case-scenario need for a given group. My idea is your vitamins/elements/amino acids requirements grow if your energy expenditure grows. Therefore, to calculate your personal need, the website takes several steps.

1. It fetches RDA or DRI values for your age/sex group from the mentioned source. Or it fetches your manually set RDA values if you use this feature.
2. Next, the website calculates EER (Estimated Energy Requirements) according to the equation from the same source using your weight, height, age, and sex as input and 1.00 as PA. PA stands for physical activity coefficient. Don't confuse it with PAL – physical activity level, which is not the same thing despite the correlation between these two terms. The result will be your basic EER.
3. Then, it calculates EER using your weight, height, age, sex, AND the PA you specified in My Metrics as input. The value will be your personal EER.
4. After that, the website sums your personal EER and the physical exercise activity data ('Activity' field) you specified (or not) on the My Day page. This data should include your physical activity when your heart rate is above 90 bpm. Luckily, modern fitness gadgets track it well. The result will be your TEE (total energy expenditure) for a given day.
5. Next, the website divides the calculated TEE by your basic EER from step 2 to obtain the coefficient reflecting how much your need grew compared to the base-case scenario.
6. Finally, the values from step 1 are multiplied by this coefficient, revealing your need for a given day. In case of requirements for amino acids some additional steps are taken, which you can learn about here. Also, in case of protein, fat and carbs, the website doesn't take the values from the guidance and doesn't apply the coefficient, using the macros approach instead. At the same time, users can discard the macros and use the coefficient from the previous step if they set their personal requirements for protein/fat/carbs manually, activate the respective option in their Metrics and remove macros values from their fields.

If you are an anonymous user or a user without defined metrics, the values from step 1 will be mean values for men and women of all age groups, and your base EER as well as your personal EER (steps 2 and 3) will be 2250 kcal (which is considered a mean energy requirement for men and women) because the website doesn't know anything about you to make the estimation more precise. All other steps remain unchanged.