A Fat-Loss Plan, Calculated Step by Step
By Jesse · Last updated August 20, 2026
Most fat-loss advice hands you one number. This page hands you the sequence, because the number is the easy part and the order is where plans quietly go wrong. Six decisions have to be made, each one constrains the next, and two of them collide in a way nobody warns you about.
To make that visible, everything below is worked out for one specific body: a 38-year-old woman, 165 cm, 82 kg, training one to three days a week — a BMI of 30.1, which the BMI calculator classifies as obese. Every figure on this page is computed from her stats by the same functions the calculators use, so nothing here is a tidied-up illustration. Substitute your own numbers as you go; the sequence is what transfers.
This is the plan that owns the order of operations. Why a deficit should be a particular size is argued in how many calories to eat to lose weight, how to keep the loss coming from fat in how to lose fat without losing muscle, and how long it takes in how long does it take to lose weight.
Step 1: Maintenance, and the size of its error bar
A deficit is defined against maintenance, so maintenance comes first. The TDEE calculator puts this body's resting energy expenditure at 1,500 kcal a day and maintenance at about 2,063 kcal once the activity multiplier for lightly active (1–3 days/week) is applied.
That multiplier is the single least reliable input in the whole plan, and it is chosen from a dropdown. Here is what the other four options would have produced for the same body:
| Activity level | Multiplier | Maintenance | Used here |
|---|---|---|---|
| Sedentary (little or no exercise) | 1.2 | 1,800 kcal | - |
| Lightly active (1–3 days/week) | 1.375 | 2,063 kcal | Yes |
| Moderately active (3–5 days/week) | 1.55 | 2,325 kcal | - |
| Very active (6–7 days/week) | 1.725 | 2,588 kcal | - |
| Athlete (twice-daily training) | 1.9 | 2,850 kcal | - |
Resting energy is calculated with the Mifflin-St Jeor equation and multiplied by the activity factor. The same body, the same day, five different answers.
The spread from top to bottom is 1,050 kcal — more than half of the intake this plan will eventually recommend, and several times larger than the difference between any two of the rate options in the next step. Nothing downstream can be more accurate than this choice, which has two practical consequences. When you are between two activity levels, take the lower one, because underestimating maintenance produces a slower plan while overestimating it produces one that does not work at all. And treat the first four weeks as a measurement rather than an execution: the rate the scale actually shows is better evidence about your maintenance than the dropdown ever was. The reasoning behind that is in why TDEE calculators are estimates, and the maintenance calories chart shows the same spread across body sizes.
Step 2: Turn a weekly rate into a calorie target
The deficit is not chosen directly. What gets chosen is a rate of loss, expressed as a percentage of body weight so it means the same thing at any size, and the deficit follows from it at 7,700 kcal per kilogram. Four candidate rates, run through the calorie deficit calculator:
| Weekly rate | Per week | Daily deficit | Daily intake | Verdict |
|---|---|---|---|---|
| 0.4% of body weight | 0.33 kg | 361 kcal | 1,702 kcal | Usable |
| 0.5% of body weight | 0.41 kg | 451 kcal | 1,612 kcal | This plan |
| 0.7% of body weight | 0.57 kg | 631 kcal | 1,432 kcal | Below resting energy |
| 1% of body weight | 0.82 kg | 902 kcal | 1,161 kcal | Below the 1,200 kcal floor |
Deficits computed at 7,700 kcal per kilogram. The floor shown is the site's general planning minimum for women, not an individualised safety threshold.
Two rows fail, and they fail for different reasons worth understanding. The 1% rate needs a 902 kcal daily deficit, which leaves 1,161 kcal — under the 1,200 kcal planning floor, so the calculator will not return it. The 0.7% rate is legal but lands at 1,432kcal, below this body's own resting energy expenditure of 1,500 kcal. Resting energy is not a floor below which eating is forbidden, and plenty of supervised diets run under it. But it is a useful tripwire: when the arithmetic starts asking for less food than your body spends lying still, the plan has stopped having any margin in it.
So this plan takes 0.5% a week — 0.41 kg, a 451 kcal daily deficit, and a target of 1,612 kcal a day. Note what that number is not: it is not a rule, it is the output of two choices you can see. And note the asymmetry hiding in it. Because the rate is a percentage of body weight, 0.5% is a smaller number every month she loses. Holding the calorie target fixed therefore means the rate slowly increases relative to her shrinking body, right up until the falling maintenance figure overtakes it and the loss stops. Step 5 shows exactly how that plays out.
Step 3: Protein first, then divide what is left
This is the step where the plan gets uncomfortable, and it is arithmetic rather than preference. The protein calculator sets a fat-loss target of 2 g per kilogram of body weight, or 164 g a day — 55 g in each of three meals. At 4 kcal a gram that is 656 kcal, which is 41% of the 1,612 kcal budget. Everything else she eats all day — all carbohydrate, all fat, every drink — has to fit inside the remaining 956 kcal.
That collision between a protein target and a small calorie budget is the part no calculator flags, and it is why protein goes first rather than last. It also survives a cross-check. The fat-loss guide argues for scaling protein to fat-free mass rather than body weight, at 2.3 to 3.1 g per kilogram of lean tissue. Her body fat percentage is unknown, so that rule cannot give one figure — but across a plausible span of 32 to 42% body fat it asks for 109 to 173g a day, and the body-weight rule's 164 g sits inside that range. Two different methods, one answer. If you want a narrower number, the body fat calculator will produce a fat-free mass estimate from a tape measure.
With protein fixed, the macro calculator puts fat at a quarter of calories and gives the remainder to carbohydrate:
| Macro | Grams | Calories | Share of intake |
|---|---|---|---|
| Protein | 164 g | 656 kcal | 41% |
| Carbohydrate | 138 g | 552 kcal | 34% |
| Fat | 45 g | 405 kcal | 25% |
Protein is anchored to body weight, fat is set at 25% of calories, and carbohydrate takes what is left. The carbohydrate and fat split is adjustable to taste; the protein figure is the one worth defending.
The carbohydrate and fat rows are negotiable and the protein row is not, which reframes the practical problem. Hitting 164 g inside 1,612 kcal is hard with food chosen for protein per 100 grams and considerably easier with food chosen for protein per calorie — a distinction our macros by food chart ranks explicitly, because the two orderings are not the same list.
Step 4: Fluid, where precision matters least
The water intake calculator puts a baseline of 2,665 ml a day for this body weight and adds 250 ml for training, giving about 2.9 litres. Include this step for completeness and then stop optimising it: unlike every other number on this page, being 20% wrong about fluid has no consequence for a healthy adult with functioning kidneys and access to a tap. Thirst plus pale urine is a better controller than any formula, and the reason the familiar rules disagree with each other is set out in how much water should you drink a day.
Step 5: What the scale will actually do
Give the plan a destination. The top of the normal BMI band at 165 cm is 67.8 kg, which is 14.2 kg away — a stated basis for the goal rather than a round number picked because it sounds achievable. At 0.41 kg a week, the body weight planner draws a straight line reaching it in 35 weeks.
That line is wrong, and wrong in a direction that matters. Maintenance calories fall as body weight falls — by about 13.8 kcal a day per kilogram at this activity level — so a fixed intake of 1,612 kcal is a shrinking deficit. Re-running the same plan week by week, recomputing maintenance from the new weight each time, gives this:
| Checkpoint | Straight line says | Recomputed says | Overshoot | Deficit that week | Share of the original deficit |
|---|---|---|---|---|---|
| Week 4 | 80.4 kg | 80.4 kg | 0.0 kg | 434 kcal | 96% |
| Week 12 | 77.1 kg | 77.4 kg | 0.3 kg | 393 kcal | 87% |
| Week 26 | 71.3 kg | 72.9 kg | 1.5 kg | 329 kcal | 73% |
| Week 52 | 60.7 kg | 66.3 kg | 5.6 kg | 237 kcal | 53% |
Both columns use the site's own functions: the straight line from the body weight planner, the recomputed column from the Mifflin-St Jeor equation applied to each week's new body weight.
At four weeks the two projections are indistinguishable, which is why the error is so easy to miss. By week 52 the straight line is 5.6 kg optimistic, and only 53% of the original 451 kcal deficit is still doing any work. The goal weight that arrives in 35 weeks on paper takes 45 weeks here. Holding the deficit genuinely constant instead would mean intake falling by about 293kcal over the year, which is the honest version of "recalculate as you go".
Two caveats, both in the same direction. This simulation lets maintenance fall only through the body-weight term of the equation; it does not model adaptive thermogenesis or the drop in spontaneous movement that accompanies weight loss, so 45 weeks is a lower bound on the real answer rather than a prediction. And the model has a mathematical asymptote — a weight at which the falling maintenance figure meets the fixed intake and loss stops entirely — which for this plan sits far below any sensible target and should be read as an artifact of the arithmetic, not a destination. The full analysis, swept across hundreds of body and deficit combinations, is in how wrong the 7,700-calorie rule is after a year.
Step 6: The review loop, which is the actual plan
Everything above is a hypothesis built on an activity multiplier chosen from a dropdown. The part that makes it a plan is the schedule for testing it: weigh most mornings, compare seven-day averages rather than single readings, measure the waist weekly at the navel, log the load and reps on two or three main lifts, and change exactly one thing every four weeks.
Seven-day average weight flat for three weeks
Most likely cause: Either intake has crept up, or the deficit has eroded as body weight fell
What to change: Weigh and log everything for one week first. If intake really is on target, cut 100 to 150 kcal or add daily movement — one of the two, not both
Losing faster than planned
Most likely cause: The maintenance estimate was too low, so the real deficit is larger than intended
What to change: Add 100 to 200 kcal. Losing faster is not a bonus here; it is the main risk factor for losing lean mass alongside the fat
Weight falling on schedule but the waist is not moving
Most likely cause: Usually measurement noise over too short a window, occasionally water retention masking the change
What to change: Change nothing. Re-measure in two weeks, same time of day, same position on the tape
Main lifts declining for three or four weeks
Most likely cause: The deficit is too aggressive for the training load, or protein is short
What to change: Raise intake to the next slower rate — 1,702 kcal here — and check protein against the target before changing anything in the gym
Hunger is unmanageable and adherence is breaking
Most likely cause: The target is wrong for this person, not the person wrong for the target
What to change: Move to the 0.4% rate. A slower plan that gets followed beats a faster one that gets abandoned
Weight up one or two kilograms overnight
Most likely cause: Sodium, glycogen, digestive contents, or menstrual cycle phase
What to change: Ignore it entirely. A single weigh-in carries more noise than a week of real fat loss contains signal
One adjustment per review. Changing two things at once means the next four weeks of data cannot tell you which one worked.
The discipline of one change per review is what turns four weeks of weighing into information. It also protects against the most common failure mode in fat-loss plans, which is not eating too much but reacting too fast: a flat week triggers a cut, the next flat week triggers another, and within two months the target is somewhere nobody chose deliberately.
What this plan cannot tell you
- Her actual maintenance calories. The 2,063 kcal figure is an estimate with an error bar of several hundred calories, which is wider than the gap between two of the rate options in step 2. Only four weeks of her own weight data narrows it.
- How much of the loss is fat. A scale cannot distinguish a kilogram of fat from a kilogram of anything else. Waist circumference and the load on the bar are the practical proxies, and both are trends rather than measurements.
- Her body composition now. The protein cross-check in step 3 had to be stated as a range precisely because no fat-free mass figure exists for her.
- Anything about food choice, health, or medication. The plan sets totals. It says nothing about which foods, how they are distributed, thyroid or metabolic conditions, medication that affects appetite or fluid balance, or the weight swings that accompany the menstrual cycle — all of which can matter more in a given month than the numbers above.
Which is the honest summary of the whole page: the value is in the order of the steps and the review loop at the end, not in the precision of any single figure. A plan built in this order with sloppy inputs self-corrects within two months. A plan built out of order with perfect inputs does not.
Common questions
How do I make a fat-loss plan?
In this order: estimate maintenance calories, choose a weekly rate as a percentage of body weight, subtract the deficit that rate implies, set protein inside the resulting budget, divide what is left between carbohydrate and fat, then fix a review date. For the worked example on this page — a 38-year-old woman, 165 cm, 82 kg, training one to three days a week — that produces maintenance of about 2,063 kcal, a 0.5% weekly rate, a 451 kcal deficit, and a target of 1,612 kcal a day with 164 g of protein. The order matters more than any single figure, because each step constrains the next.
Where does the 1,612 kcal target in this plan come from?
Maintenance minus the deficit the chosen weekly rate implies — not a fixed number from a chart. A rate of 0.5% of body weight per week needs a 451 kcal daily deficit at 82 kg, which gives 1,612 kcal against a maintenance estimate of 2,063 kcal. The same percentage produces a smaller deficit as you get lighter, which is why a fixed calorie target slowly stops working.
Why is my calorie target below my BMR?
Because the deficit was set from a weekly rate without checking it against resting energy. On this page the 0.7% rate produces 1,432 kcal a day, which is below this body's estimated resting energy expenditure of 1,500 kcal. That is not automatically dangerous — resting energy is not a floor below which eating is forbidden — but it is a signal that the plan is leaning hard on one side of the equation. The better fix is usually a slower rate or more daily movement rather than a lower number.
How long will it take to lose the weight?
Longer than the straight-line arithmetic says. Getting from 82 kg to 67.8 kg is 14.2 kg, which a fixed 451 kcal deficit predicts will take 35 weeks. Recomputing maintenance calories every week as body weight falls puts it at 45 weeks instead — and even that is optimistic, because it models only one of the reasons a deficit shrinks.
Why does protein get set before carbohydrate and fat?
Because it is the only one of the three with a floor, and at this calorie level the floor is expensive. The target here is 164 g a day, from 2 g per kilogram of body weight, and what it costs is the point: 656 kcal, or 41% of a 1,612 kcal budget, leaving 956 kcal for everything else. Protein is the one macro to set before the others, because it is the one that protects lean mass while the deficit runs.
How often does a plan like this need recalculating?
More often than most plans suggest. Maintenance falls by roughly 13.8 kcal a day for every kilogram lost at this activity level, so a target set at the start is a smaller deficit every month. In the year-long projection on this page, only 53% of the original deficit is still doing any work by week 52. Recalculating every 4 to 6 kg, or whenever weight has been flat for three weeks, keeps the plan honest.
What is the one change to make at a review when the scale has stopped moving?
Check the input before changing the output. Weigh and log everything for a week, including the things usually estimated: oils, sauces, drinks, and anything eaten standing up. If intake really is on target and the seven-day average has not moved in three weeks, then the deficit has eroded and the choice is to cut 100 to 150 kcal or to add daily movement. Do one of those, not both, and give it another three weeks before judging.
Is a 500 calorie deficit right for everyone?
No, because it means very different things at different body weights. For this 82 kg body, 451 kcal is 0.5% of body weight a week; the same deficit for someone at 60 kg is closer to 0.7% a week, which is faster than the evidence supports for anyone hoping to keep muscle. Percentages travel across body sizes. Fixed calorie deficits do not.
How accurate is this plan?
The arithmetic is exact and the inputs are not. The maintenance estimate carries an error bar of several hundred calories, which is larger than the difference between two of the rate options on this page, and tracked intake carries its own error on top. That is why the plan ends with a review loop rather than a promise: the first four weeks are a measurement of your own maintenance, and everything after that is a correction.
These are general estimates for healthy adults, not medical advice, and the worked example is an illustration rather than a prescription for anyone. If you are pregnant, under 18, have a medical condition, or a history of disordered eating, talk to a doctor or registered dietitian before starting a calorie deficit. See our methodology for the sources behind these figures.