Day 99: TDEE week 1 update. Plus, everything you always wanted to know about TDEE (but were afraid to ask).

Today was my week 1 weigh-in for the TDEE project. Stats:

Week 1
Weight: 249.8
Change this week: -1.6
Average daily kcal this week: 2418

So what does this mean, exactly?

It means one of two things. It might mean that ~2400 kCal is my TDEE; +/-1.6 lbs is well within average weekly weight fluctuation. Or it might mean that ~2400 kCal is a caloric deficit for me, and I will continue to lose weight at that intake. In the latter case, it doesn’t actually tell me what my TDEE is. I can’t know for sure what 2400 kCal is without continuing the project. My initial goal was actually 2200 kCal per day. However, given my result this week, I’m taking an executive decision to make an early upward adjustment to 2400 kCal per day.

So what is this TDEE project, anyway? 

TDEE stands for Total Daily Energy Expenditure. By virtue of being alive, every living thing constantly expends energy, because cellular processes require energy. TDEE is the amount of energy your body burns each day. It’s the sum of 3 things: your (1) BMR (Basal Metabolic Rate, also called RMR, or Resting Metabolic Rate), or the number of calories your body would burn if the only thing you did all day, every day, was lie flat in bed, unmoving; (2) the number of calories you burn during intentional physical exercise; and (3) NEAT (Non-Exercise Activity Thermogenesis), or the number of calories you burn as you go about your daily tasks that aren’t considered intentional daily exercise — walking around, fidgeting, cleaning, sitting up, taking the stairs, standing. Because everyone’s body and daily activities are different, everyone’s TDEE is different.

From a food perspective, it’s the amount of food in calories you need to eat every day to maintain your current weight. If you eat above TDEE, you’re eating more calories than your body needs, and your body will add weight (fat if you are sedentary, lean body mass + fat if you lift heavy weights). If you eat below TDEE, you’re eating fewer calories than your body needs, and your body will lose weight (fat + lean body mass in some combination based on size of caloric deficit, amount of protein consumed, and whether you lift heavy weights).

You can have your BMR tested professionally, but unless you’re participating in a study, it’s unlikely you’ll find yourself in a position to have your TDEE measured. But you can figure out TDEE yourself with a little patience, care, and bookkeeping. Here’s how:

  1. Take your body weight. No judgements or self-loathing allowed, it’s for science!
  2. Choose an average daily caloric intake close to your estimated TDEE.
  3. Every day for 3-4 weeks (longer is better) eat approximately the predetermined number of kCal. You need to track your calories somewhere like myfitnesspal to make sure you’re eating the right amount. You need to be honest. If you had a bite of your kiddo’s cake or a few peanuts or whatever, you have to track it, because those calories add up. Remember, no judgements or self-loathing allowed, because it’s for science!
  4. Weigh yourself once per week under the same conditions in which you took your weight the first day. Track your weight. No judgements, science, etc.
  5. After the 3-4 weeks, regroup. If your weight has been fairly consistent (weekly variation okay, but you shouldn’t be consistently gaining or losing), congratulations, you’ve found your TDEE! If you keep eating this number of calories, your weight will remain constant. However…
  6. If your weight has increased, you were eating above your TDEE. Go back to step 2; try 200 kCal less per day and repeat the process. If your weight has decreased, you were eating below your TDEE. Go back to step 2; try 200 kCal more per day and repeat the process.
  7. Once you’ve established your TDEE, you can proceed to implement a safe deficit for weight loss (or surplus, if you’re trying to gain).

Why bother finding your TDEE if you’re seeing the numbers on the scale change the way you want them to? Because evidence shows the only weight loss that’s sustainable over the long-term is slowthink 1-2 pounds per week (and honestly, 2 pounds is pushing it). To lose ~1 pound per week, you should eat at a caloric deficit of ~500 kCal per day; to lose ~2 pounds per week, you should eat at a caloric deficit of ~1000 kCal per day. But you have no way to know what the right caloric intake is for you if you don’t know your unique TDEE based on your BMR and activity level.

Relevant questions: how do you estimate your TDEE in the first place? Unless your metabolism is severely compromised due to a long-term, active, severe eating disorder or a hormonal imbalance, your TDEE is likely much higher than you’ve been led to believe.* This calculator is great. You might freak out because the number seems so high. It recommended 3600 for me, which was just astounding. I don’t know how I would even get that many calories every day without drinking heavy cream or eating sugar by the spoonful, and who wants that? Ew. I picked a smaller number (2200 kCal per day) that felt achieveable, knowing that I would probably have to adjust upward.

Why is the estimated TDEE so much higher than the typically recommended RDA? The government estimates average daily caloric intake as 2000 for women and 2500 for men. But these numbers are based on self-report studies, and self-report is notoriously inaccurate; people consistently underestimate caloric intake and overestimate energy expenditure. By a lot. “2000 per day” is probably more like 2500-3000 when accounting for actual portion size, bites of things here and there, and binges. Primary care physicians, the majority of whom have had little substantive training in nutrition, frequently recommend 1200-1800 kCal per day for weight maintenance, because if people are getting fatter without significant change in caloric intake, then we must need less calories than common wisdom would suggest. However, someone reporting 1500 kCal per day is almost certainly underestimating.

Why is 1 pound per week better than 2 pounds per week? If you listen, your body is actually very good at telling you when to eat (hunger signals mean your body needs fuel). When you eat too far below your TDEE, you will spend a lot of time hungry, and that’s not sustainable: odds are, eventually you’ll binge to make up the deficit; these binges are often ongoing, with deficit days plus binge days averaging out to a daily caloric surplus. This is known as a restrict-and-binge cycle and it’s the cycle that plagues dieters; it’s why people don’t lose weight and keep it off on 1400 kCal per day. It’s not a failure of willpower. Your body needs the calories to function and you are giving your body what it needs. Losing 1 pound per week is preferred to 2 pounds per week because with a daily deficit of 1000 kCal (~2 lbs per week), you will be hungry in a way that you simply won’t be if you eat at a smaller deficit, and your body is a lot more likely to make up for it with a binge.

In a nutshell: if you simply accept that you need to eat, for instance, 2500 kCal per day, and then eat 2500 kCal per day, thereby preventing intense hunger pangs and cravings, you will maintain your weight! Whereas if you believe you should eat 1600 kCal per day, but you repeatedly binge because your body is hungry, you’ll gain weight.

Eat food. It’s good for you!

Fitness today
Miles to Mordor: 2.08
Strength training, foam rolling, stretching

In search of my TDEE:
kCal: 2562

* standard disclaimer: I’m not a doctor, registered dietitian or “nutritionist”; it will be different for folks who’ve had weight loss surgery; get your BMR tested if your curious; the TDEE calculator is just an estimate; etc etc.

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5 thoughts on “Day 99: TDEE week 1 update. Plus, everything you always wanted to know about TDEE (but were afraid to ask).

    • If it helps someone out that would be great!

      I’ve spent a lifetime switching between intentionally restricting calories (over restricting, in hindsight, with associated under-reporting and binge behaviors) and unintentionally restricting calories through “healthy” or “clean” eating (with associated binge behaviors) and the only place it’s gotten me is the plus size clothing department (and I know plenty of people who’ve had exactly the same result). It’s time for an overhaul… Moderation it is.

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