A client's weight has not moved in ten days and they have just messaged you about it. The instinct is to drop their calories, because that is a visible response and it makes you look like you are coaching. Most of the time it is the wrong move, and you will not find out it was wrong for another three weeks.
The reason is that adjusting macros is not a nutrition decision. It is a data decision. You are being asked to infer what a client's body is doing from a set of numbers, and every one of those numbers can be wrong for reasons that have nothing to do with their metabolism. Adjust against bad data and you have not just made one bad call — you have destroyed your ability to interpret the next four weeks, because you no longer know which change caused what.
This is the order to work through, and the reason the first step is first.
Check adherence before you touch the number
You cannot adjust against a target the client is not hitting. If they averaged 2,400 calories against a 2,000 target, their intake was never 2,000, so lowering the target to 1,800 does not lower their intake — it just widens a gap that was already there and teaches them the number is theoretical.
So the first question is never "is this working?" It is "did they actually do it?"
Adherence has three separate failure modes and they need different fixes:
- They did not log. You have no data. Nothing else in this article applies.
- They logged, and missed the target. You have data, and it says the plan is not being followed.
- They logged, hit the target, and nothing happened. This is the only case where changing the number is the right response.
The usual working standard is that a client needs to have logged most days of the week — five of seven at an absolute minimum, six or seven if you want to act on it — and landed near the target on those days. If they are consistently under that, the problem is the system around the target, not the target. That might mean the tracking itself is too hard, which is a teaching problem covered in how to teach clients to track macros. It might mean the target does not fit how they actually eat, in which case a meal plan gives them something to follow rather than something to hit. It might mean the plan is too rigid to survive a normal week, which is what flexible dieting is meant to solve.
None of those fixes are a new macro target. Changing the number when adherence is the problem is the most common mistake in nutrition coaching, and it feels productive precisely because it is easy.
You need two weeks, not one weigh-in
A single weigh-in tells you almost nothing. Day-to-day body weight moves with water, sodium, carbohydrate intake, sleep, training load, bowel timing and the menstrual cycle — swings of a kilogram or two inside a week are ordinary and have nothing to do with fat.
So you do not read weigh-ins. You read weekly averages, and you compare averages to each other.
The working minimum is two full weeks of averaged data before you change anything. Three is better, because two weeks can still be distorted by a single event — a holiday weekend, a heavy salty meal on a weigh-in day, the first week of a new training block. Any week that contains one of those is a week you note and discount, not a week you average and act on.
For an average to mean anything you need enough weigh-ins in it. Four or more days a week, taken under the same conditions — same time of day, after the toilet, before eating, minimal clothing. Three weigh-ins taken at random times across the day are not an average, they are three unrelated numbers.
Reviewing this is where a food log that already sums the week saves you the arithmetic. Fitsly's nutrition tools show a client's average daily calories against their goal, how many of the seven days they logged, and their weekly macro averages — which is the adherence question and the intake question answered before you have opened a spreadsheet.
Work out the trend before you decide anything
Once you have two clean weekly averages, the comparison is straightforward: subtract one from the other and express it as a percentage of body weight, because a 0.5 kg change means something very different at 55 kg than at 120 kg.
The rates coaches generally work to are these:
| Goal | Weekly change as a share of body weight | For a 80 kg client |
|---|---|---|
| Fat loss | 0.5% to 1% down | 0.4 to 0.8 kg down |
| Maintenance | Within about 0.25% either way | Under 0.2 kg either way |
| Lean gain | 0.25% to 0.5% up | 0.2 to 0.4 kg up |
Faster is not better. Fat loss well above 1% a week, sustained, tends to come with more lean mass lost and more of the hunger and fatigue that ends diets early. Gains well above 0.5% a week are mostly fat.
Weight is also not the only reading. If the scale has not moved but waist measurement is down and the client's lifts are up, something is happening and the scale is simply not the instrument that shows it. Reading those together is the subject of how to assess client nutrition progress — for the purposes of this decision, treat a flat scale with improving measurements as progress, not a stall.
The decision matrix
With adherence established and a trend calculated, the action follows. This is the whole procedure on one page.
| Weight trend | Adherence | What it means | What to do |
|---|---|---|---|
| At target rate | Good | The plan works | Nothing. Do not touch it. |
| At target rate | Poor | You do not know why it works | Fix logging. Hold the target. |
| Stalled 2+ weeks | Good | Genuine plateau | Adjust calories 5–10% |
| Stalled 2+ weeks | Poor | Unknown intake | Fix adherence. Hold the target. |
| Stalled 1 week | Good | Probably noise | Wait another week |
| Moving too fast | Good | Deficit too aggressive | Add calories back 5–10% |
| Moving too fast | Poor | Under-eating, not tracking | Address the behaviour, not the number |
| Wrong direction | Good | Target genuinely miscalculated | Recheck the starting number |
| Wrong direction | Poor | Almost certainly intake | Fix adherence first |
Two rows are worth dwelling on. "At target rate, good adherence — do nothing" is the row coaches break most often, usually out of a feeling that a check-in with no changes is a check-in where they did no work. It is not. Holding a working plan is a decision, and telling the client why you are holding it is the coaching.
"Wrong direction, good adherence" almost always means the starting target was wrong rather than the client being an outlier — which is a reason to revisit how the number was set in the first place, covered in how to set a client's calorie target.
How much to change, and which macro to move
When a change is warranted, keep it small. The convention is 5% to 10% of current calories — for a 2,000 calorie target, 100 to 200 calories. Big cuts feel decisive and cost you the next adjustment, because once you have taken 400 calories out you have spent the room you needed for the following month.
Which macro carries the change:
- Protein stays. It is the target you defend, not the one you trade against, especially in a deficit. Set it once and leave it — see how to set protein targets for clients.
- Carbohydrate and fat carry the change. A 200 calorie cut is roughly 50 g of carbohydrate, or roughly 22 g of fat, or a split of the two.
- Split by what the client will tolerate. A client who trains hard five days a week usually copes better with the cut coming mostly from fat. A client whose main complaint is hunger between meals often does better keeping fat and taking it from carbohydrate. Ask them.
Change one thing at a time. If you cut calories and add two training sessions and start a step target in the same week, and the weight moves, you have learnt nothing about which lever did it.
Wait the full window before judging it
Two to three weeks. That is how long it takes for a change of 5% to 10% to show through the noise, and it is not negotiable just because the client asked on day four.
The first week after any change is close to unreadable. A carbohydrate cut drops water weight quickly, which looks like a fast result and is not one; adding calories does the reverse and looks like failure. Both resolve by about week two.
So the review cadence is: change, then two weeks of untouched data, then decide. In practice that means most clients get an adjustment roughly monthly, and a client on a plan that is working can easily go two or three months without one.
Adjusting too often is the error that costs the most
If you change something every week, every result you get is confounded. You cannot say whether week three's drop came from week three's cut or week two's, because their effects overlap. You have made your own data unreadable, and the only way back is to hold everything constant for a month — which is exactly what you were unwilling to do in the first place.
There is a second cost. A client whose targets change every seven days stops treating any of them as real. Numbers that move constantly read as guesses, and a client who thinks you are guessing stops trying to hit them precisely, which degrades the data further.
The discipline is simple to state and hard to hold: one change, one variable, then wait. A check-in where you look at the data and say "this is working, keep going" is a good check-in.
When to refer out
Everything above is general nutrition guidance for fitness coaching, and it has limits that are worth knowing before you cross them.
Refer to an accredited dietitian when a client has a diagnosed medical condition that nutrition affects — diabetes, kidney or liver disease, coeliac disease, an eating disorder or a history of one. Refer when a client is pregnant or breastfeeding, when they are taking medication that interacts with intake, or when they are under 18. Refer when repeated sensible adjustments produce no response at all, because that is a reason to have someone check for something you are not qualified to look for.
Also refer, or at least stop adjusting, when the tracking itself starts looking disordered: distress at missing a target, secrecy about eating, an unwillingness to eat anything that is not weighed. Lowering the number is the wrong response to that, every time. Check what your certification and your insurance actually cover in your jurisdiction, and stay inside it.
