Bring a puppy home and the calendar changes overnight. There's a 6 a.m. trip outside, a lunchtime check-in, and an evening walk that happens whether or not you had other plans.
A few weeks in, people notice the scale or their workout log looks different and start hunting for an explanation. Usually the explanation is the small animal asleep on the couch.
First, notice what actually changed
More short trips outside and more time on your feet, yes. But also less sleep, a rushed breakfast, and a couple of gym sessions that quietly didn't happen.
Those effects point in different directions. That's worth sitting with before deciding whether your TDEE estimate is wrong.
Don't change three things at once
The temptation is to fix everything on a Monday: new activity level, fewer calories, an earlier alarm. Then two weeks later you have no idea which change did what.
Give the new routine two or three weeks to settle. Keep eating roughly the way you were. Check a weekly weight average if you track it, and adjust one thing at a time — 100–200 calories is plenty for a first step.
The activity field is a weekly summary
A puppy adds a dozen small walks, not a structured workout. That's exactly the kind of unlogged movement the activity multiplier is supposed to cover, and it's also the field with the most uncertainty.
Formulas already carry about 10–20% individual error. A few extra laps around the block fit comfortably inside that band. If the new pattern clearly holds for a month, then it's reasonable to revisit the setting.
Sleep is the sneaky part
Short nights change appetite, patience, and how much you feel like moving. If a week feels off, that's a more likely explanation than a broken metabolism.
Be a little generous with the plan during the chaotic month. The puppy will eventually sleep through the night, and the routine you keep in the meantime is the one that'll still be there.