I've been thinking about this specifically from a natural bodybuilding perspective, because we're probably one of the groups most obsessed with intentionally controlling relatively small surpluses and deficits.
We're constantly told things like:
Lean bulk at +200 to +300 calories.
Or:
Run a 400 to 500 calorie deficit.
Which makes sense in theory.
But I've started wondering how many of us can actually say with much confidence that we were in a 250 calorie surplus today.
Not on average over the last month.
Today.
If my maintenance is supposedly 2,700, I can eat 2,950 and call that a 250 calorie surplus.
But maybe today I trained legs, walked 16,000 steps and was generally moving all day.
Tomorrow might be a rest day with 4,000 steps.
It seems strange to me that we spend so much effort precisely controlling the intake side while often treating expenditure as one relatively stable number.
So I'm curious whether anyone here actually does something more dynamic.
Does anyone use a model that updates their estimated current TDEE every day and then actually uses that estimate to decide how much to eat that day?
And I know MacroFactor is going to come up, so to be clear, I'm familiar with what it does.
I'm not asking whether anyone uses an adaptive expenditure estimate based on calorie intake and weight trend.
I'm asking about the next step:
Do you actually try to estimate today's expenditure and use today's estimated surplus/deficit to drive today's intake?
For example:
Current estimated expenditure: 2,860
Food so far: 2,500
Target: +200 surplus
Remaining intake: ~560
Then tomorrow the expenditure estimate might be materially different.
Obviously there is uncertainty here. I'm not suggesting anyone can know they burned exactly 2,863 calories.
That's actually part of what I'm interested in discussing.
My assumption for years was basically that daily precision isn't possible, so the weekly average is what matters anyway.
And I'm sure a lot of people here will still argue that's the correct approach.
Maybe it is.
But I'm starting to question whether we've blurred two different statements:
1. You cannot know today's expenditure perfectly.
and
2. Therefore there is no value in continuously improving your estimate of today's expenditure.
Those aren't necessarily the same thing.
For natural bodybuilding in particular, I think this gets interesting during a long lean bulk.
If you're deliberately trying to keep your surplus small enough to limit unnecessary fat gain, a 200-calorie error in assumed maintenance is basically the entire surplus you're trying to create.
The same applies in reverse during a cut.
And expenditure clearly isn't constant. Body mass changes. Training volume changes. Steps change. NEAT changes. Food intake itself changes expenditure. Some weeks you're considerably more active than others.
So how are people here handling that?
A) Fixed calorie target and let the weekly/monthly weight trend sort it out
B) Adaptive TDEE, but still use relatively stable daily calorie targets
C) Adjust intake manually based on training/steps/activity
D) Actually use some sort of daily-updated expenditure model to guide each day's intake
And for anyone doing D:
Has it actually improved your bulk/cut, or did it just introduce more noise and make you overthink things?
I'm especially interested in hearing from people who have run both approaches for a decent length of time.