This is something that will require a little bit of patience, and trial and error. While there are a ton of calorie / TDEE calculators and formulas out there, there can be (mostly minor) variations in metabolic rate (and activity level) that will make the numbers they spit out good only as a place to start that you refine over time. You should never expect to get a perfect number from a calculator, or for any number to be the same every day, forever.
To get the best results, follow this step by step process:
- Use any TDEE calculator you can find on the internet. Seriously, any of them are fine. This is just to get a general place to start – don’t treat it as gospel and don’t worry about selecting the perfect activity level.
- Target +/- 10-20% of this number, depending on your goal of weight gain or loss.
- Start tracking everything you eat that has calories. Everything.
- Start weighing yourself at roughly the same time every day – preferably in the morning, on an empty stomach and bladder/bowels.
- Make use of the 3-Suns Adaptive TDEE Spreadsheet. It will give you an estimate as a starting point, and as you enter your weight and calories consumed each day, it will calibrate and give you a more accurate picture of your TDEE over time.
- If, after a few weeks, your weight is not changing, adjust your calorie target either up (for weight gain) or down (for weight loss), and keep on trucking.
For longer, more detailed information on diet, read over the Improving Your Diet page.