How do I decide whether to bulk or cut?

By body fat range and by what your last block did, not by season. Above roughly 15 to 18 percent body fat a surplus partitions worse and a cut is usually the better first move; below about 10 percent, gaining is easier and holding is harder. The more actionable input is the trend on the scale next to your waist measurement.

What surplus should I set?

Two hundred to two hundred and fifty calories a day for most trained lifters. A pound of lean tissue costs roughly 2,500 kcal, so a 0.5 lb per week gain needs only 179 a day. Anything above the ceiling has nowhere to go but fat.

What is a refeed phase?

A deliberate return to maintenance calories after a period of deficit, before attempting a surplus. Go there fast rather than crawling — metabolic adaptation largely dissipates simply by eating at maintenance, and the slow reverse diet mostly delays the point at which anything useful starts happening.

Does Base tell me what to change?

Yes, from a simple rule table comparing your actual rate of change against your target rate. It is deliberately simple because the underlying signal — a surplus of a couple of hundred calories against a maintenance figure with its own error bar — does not support anything more sophisticated.

How often should I change my surplus?

Rarely. Adaptive maintenance runs on a fourteen-day window, so a change made on one week of data is a change made on half a window. Three consecutive weeks pointing the same direction is a signal; one is weather.

The Strategy Screen: The Weekly Brain

The four decisions

Phase. Refeed, gain, maintain or cut. This is the framing everything else inherits, and getting it wrong makes every subsequent decision wrong in the same direction.

Target rate. How fast, in pounds per week. Not how much you want to gain — how fast you are willing to gain it.

Surplus or deficit. Derived from the rate rather than chosen independently, because the rate is the thing your body can actually deliver and the calorie figure is downstream of it.

Where it goes. The partition model: how much of the surplus fits inside your lean-gain ceiling and how much has nowhere to go but fat.

Getting out of a deficit first

If you are arriving from a sustained deficit — and a lot of hybrid athletes are, because endurance training plus an unmeasured maintenance figure produces one accidentally — do not go straight into a surplus.

Refeed for one to two weeks. Calories up to estimated maintenance, and go there fast.

The popular eight-to-twenty-week slow reverse diet is not well supported. Metabolic adaptation largely dissipates simply by eating at maintenance, and crawling upward mostly delays the point at which anything useful starts happening. The benefit comes from being at maintenance, not from the ramp.

Expect three to six pounds on the scale in two weeks, and none of it is fat. Refilling muscle glycogen binds roughly three grams of water per gram of glycogen — two to four pounds for a trained male — and the digestive tract refilling adds another one to two. Your waist will tick up for the same reason.

This is the single most likely moment for someone to conclude the plan is failing when it is working exactly as intended, which is why the screen says it in advance rather than after.

The surplus, and why it is small

ceilingKcal  = leanCeilingLbsPerWk * 2500 / 7      // ~179 at 0.5 lb/wk
toLean       = min(surplus, ceilingKcal)
toFat        = surplus - toLean
leanLbsPerWk = toLean * 7 / 2500
fatLbsPerWk  = toFat  * 7 / 3500

A pound of lean tissue costs roughly 2,500 kcal because it is mostly water; a pound of fat costs 3,500. Muscle can only be built so fast, so surplus past the ceiling has nowhere to go but fat.

Training age	Realistic gain	Daily energy needed
Untrained, first year	~1.0 lb/week	~357 kcal
Intermediate, 2–4 years	~0.5 lb/week	~179 kcal
Advanced, 5+ years	~0.25 lb/week	~89 kcal
Near potential	~0.125 lb/week	~45 kcal

An advanced lifter's entire lean-gain budget is under a hundred calories a day, which is smaller than the error bar on any calorie estimate you can make. That is not an argument against tracking; it is the argument for steering by the trend on the scale rather than by the arithmetic, because the arithmetic cannot resolve a signal that small and the scale can.

The calculator runs it on your numbers.

The rate is earned, not assigned

The screen asks how close you are to your training potential, and the answer sets the ceiling.

That question exists because the alternative — assigning everyone the same rate — produces the standard failure: an advanced lifter running an intermediate's surplus, gaining at an intermediate's scale rate, and discovering at the end of the block that the difference went to fat.

The honest version is that the rate falls fast with training age, and a plan built on a rate you cannot deliver is a plan that buys fat.

What the app recommends

Before you ask anyone, the screen applies a rule table: your actual rate of change against your target rate, producing hold, raise or cut.

It is a simple rule table on purpose. The underlying signal is a surplus of a couple of hundred calories against a maintenance figure that has its own error bar, and a confident-looking recommendation from a model that cannot resolve the signal is worse than a plain one.

"You are 22% over your target gain rate" is usually enough on its own.

For hybrid athletes specifically

Two things about this screen change when endurance work is in the picture.

The surplus is more fragile. At 179 kcal a day, a single unaccounted run erases it. That is why the surplus is set against measured maintenance rather than a predicted figure — the measurement contains the endurance work whether or not you logged it. The method.

Hold endurance volume steady during a gaining phase. A ramping endurance load and a fixed surplus are incompatible: each new week of volume quietly eats more of the surplus, the trend goes flat, and nothing on any screen explains why. Pick a volume, hold it, gain, and ramp endurance in a different block.

When to change something

Rarely, and on a pattern rather than a week.

Pattern	Reading
One week off target	Noise. Do nothing
Two weeks same direction	Watch it
Three weeks same direction	Act
Trend flat, waist up	Recomposition going the wrong way, regardless of the scale
Trend up, strength flat, recovery down	Surplus too large or endurance load too high — deload before diet

Adaptive maintenance runs on a fourteen-day window. A change made on one week of data is a change made on half a window, and it invalidates the window the next reading depends on.

What to do next

The weekly check-in is where these settings get tested against what actually happened, and when to cut or bulk covers the phase decision in more detail than a screen can.