You went for a run this morning. Your watch says you burned 450 calories, and your tracker has helpfully added them to your budget, so tonight there's room for dessert that wasn't there yesterday.
It feels fair. You did the work, so you earned the food.
The question to ask first is where your target came from. If it was built from an activity level that included your workouts, your run is already in it — and the 450 calories on your wrist are the same run, counted a second time.
Your target already has your exercise in it
A calorie target starts with an estimate of what your body burns doing nothing at all: the standard formula, from your sex, age, height and weight. Then it's multiplied by an activity factor, and that factor is where your exercise lives.
The factors Graham uses are the usual five. 1.2 for a desk job and no exercise. 1.375, 1.55 and 1.725 as the week gets more active. 1.9 at the top, for people training hard or doing physical work all day. When you describe your week during setup, what you say picks one.
That multiplier is not small. Take a 38-year-old man, 5'11" and 195 pounds. At 1.2 his maintenance works out to about 2,190 calories a day. At 1.55, the middle of the scale, where someone exercising a few times a week usually lands, it's about 2,830 calories. The gap is roughly 640 calories, every day — about 4,500 a week.
That's his exercise. It's already in the target, spread evenly across all seven days, rest days included. So on a Wednesday when he doesn't run at all, he's still eating a share of the runs. And on the days he does run, the target was already paying for it before he laced up.
Add the watch's 450 calories on top and the run gets paid for twice.
Count it once
That's really the whole rule, and it cuts both ways. Your exercise can be counted in the activity level, or it can be counted on the day. It can't be both.
Some trackers are built the second way on purpose. Their activity question is only about your job — desk, on your feet, physical work — and workouts are left out of the base target so they can be added back as they happen. That's consistent. It stops being consistent the moment the setup question also asked how often you exercise, and you answered it. It's worth finding out which kind you're using, because the answer to this whole question depends on it.
If your tracker put you at its lowest activity level because you have a desk job, but you also train four days a week, your target is too low and eating something back on training days is a rough correction for it. The better fix is to change the activity level so it describes the week you actually have. Then the target is right on its own and you don't need to redo the arithmetic every time you work out.
If your level already describes your week honestly — and most people answering "a few workouts a week" are describing their week honestly — then an ordinary workout needs nothing added. It's the week the target was built for.
The number on your wrist is an estimate of an estimate
There's a second reason to be careful with that 450-calorie figure, separate from double counting.
A step count is a count. The device registers each one, and whatever its error, it's an error in counting something real. A calorie figure is different. Nothing on your wrist measures energy. It infers it, from your heart rate, your weight, your age and a model the manufacturer doesn't publish, and the answer arrives with a precision it doesn't have.
Some of the figures floating around are also total burn, including what you'd have spent sitting on the sofa for that same hour. That part is already in your baseline. Counting it again because you happened to be running at the time is double counting of a quieter sort.
None of that makes the number useless. A watch is a decent guide to whether today was a bigger day than yesterday, because its errors stay roughly the same from one day to the next and mostly cancel against themselves. It's a much worse guide to how many calories you should add to a budget.
What to do on a genuinely big day
A long hike, a race, a day of moving furniture. Days like that are well outside whatever week your activity level describes, and you'll probably be hungry.
Eat. You don't need a number to justify it, and you certainly don't need your watch's number. A day that runs over its target doesn't break anything, and the trend is built out of weeks, not days. If big days are occasional they wash out. If they're regular, they're telling you your activity level is wrong, and that's the thing to change.
And if you want to know whether your target is actually right, there's a better instrument than your wrist. Your weight trend over a few weeks is the only measurement that sees everything you ate against everything you burned, run included, with nobody's model in between. If it's moving at the pace you asked for, the target is right, whatever your watch said. If it isn't, the target should move, and that's a question for a few weeks of readings, not for one of them.
What Graham does with this
Graham can read your step count, and a watch's activity figure if you wear one. He'll say the steps as they are — you're at 11,000 today — because a step count is a measurement. The watch's calorie figure never leaves the code as a number at all. It gets compared against your own recent weeks, and what comes out is a word: quieter than usual, or more active than usual. On an ordinary day nothing comes out at all, because an ordinary day isn't worth remarking on.
What he won't do is turn any of it into food. No that's about 300 calories, no you've earned dessert, no extra room tonight. He knows a steps-to-calories rule of thumb, and it would feel helpful to use it, which is exactly why the rule against it is written out in full. If you ask him how many calories you burned, he'll tell you he doesn't work in burned calories, and that your target already accounts for how active you are.
A big day gets a reaction in words — you've been on your feet today — and every number stays where it was. The run was always going to count. It just gets to count once.
— Ryan