How fast you should lose weight is best expressed as a percentage of body weight per week, and the calculator offers three settings: 0.3%, 0.5% and 0.75%. For a 75 kg person that is roughly 0.23, 0.38 and 0.56 kg a week. Faster is possible on paper, but the one controlled comparison we can point to found that the slower of two rates preserved lean mass better in athletes who were lifting — and the rate you can actually hold beats the rate that looks fastest.

Rates as a percentage of body weight

The calorie deficit calculator never asks "how many kilos a week?" It asks for a rate, and derives the kilos:

RatePer week at 60 kgAt 75 kgAt 90 kgAt 110 kgDaily deficit at 75 kg
Conservative 0.3%0.18 kg0.23 kg0.27 kg0.33 kg248 kcal
Moderate 0.5%0.30 kg0.38 kg0.45 kg0.55 kg413 kcal
Aggressive 0.75%0.45 kg0.56 kg0.68 kg0.83 kg619 kcal

The deficit column is weekly kg × 7,700 ÷ 7. Because the rate rides on current body weight, the same setting produces a gradually smaller deficit as the diet goes on. That is intended: a deficit that stayed fixed while you got lighter would become a larger and larger share of your expenditure.

75 kg73 kg71 kg69 kgwk 0wk 4wk 8wk 1272.3 kg70.6 kg68.5 kgAt 75 kg, week 1conservative · 0.3%/wk0.23 kg → −248 kcal/daymoderate · 0.5%/wk0.38 kg → −413 kcal/dayaggressive · 0.75%/wk0.56 kg → −619 kcal/daycap: 35% of TDEEfloors: 1,500 / 1,200 kcalArithmetic from the algorithm's constants — not a forecast of anyone's weight.
Fig. How the three weekly rates play out for a 75 kg example over 12 weeks, as the algorithm's arithmetic: each week's target is a fixed percentage of current body weight (0.3%, 0.5%, 0.75%), converted to a daily calorie change at 7,700 kcal per kg ÷ 7. Two guard rails always apply: the daily change is capped at 35% of TDEE, and the target never goes below the calorie floors (1,500 kcal men / 1,200 kcal women on the standard setting). A model of the rule, not a prediction — real scale weight moves in a noisier, slower line.

The MacroDiet FAQ describes the usual band as 0.25–0.75 kg per week and says that losing more than 1 kg a week "often involves muscle loss and is difficult to maintain long-term." The calculator's three settings sit inside that band for body weights up to about 100 kg; above that, the aggressive rate crosses 0.75 kg and the 35% cap starts to do work.

What faster costs

The clearest evidence we can cite is a randomised trial in 24 elite athletes who all kept four resistance sessions a week1. One group targeted a 0.7% loss of body weight per week; the other targeted 1.4%. Both groups lost about 5.5% of body weight, so the comparison is between two speeds to the same destination.

Slow group (target 0.7%/wk)Fast group (target 1.4%/wk)
Achieved rate0.7% per week1.0% per week
Time to lose ~5.5%8.5 weeks5.3 weeks
Energy intake cut by19%30%
Fat mass change−31%−21%
Lean body mass change+2.1%−0.2%

Source: Garthe et al. 20111. The slow group gained lean mass while losing fat; the fast group held lean mass flat and lost proportionally less fat. The authors' conclusion is that athletes who want to keep or gain lean mass and 1RM strength during a loss phase should aim for about 0.7% of body weight per week.

Read the limits honestly. This is one trial, small, in trained athletes with a supervised programme, and the fast group did not lose lean mass — it just did not gain any. It does not tell you what happens to an untrained person, or to anyone not lifting. What it does show is the shape of the trade: the faster rate cut intake by a third instead of a fifth, got there three weeks sooner, and gave up the lean-mass gain. Notice, too, that the trial's *slow* rate is close to the calculator's *aggressive* setting.

Beyond the trial, the costs of a faster rate are mechanical: a bigger deficit means less food to build protein and the fat floor out of, a higher protein target per kilogram (the calculator adds 0.2 g/kg on any loss goal), and more of the day spent hungry. None of that is an outcome claim; it is what a larger negative number does to the rest of the macro arithmetic.

In plain terms: faster gets you there sooner and asks more of you every day you are on the way.

Choosing a rate you can hold

The rate that matters is the one you can sustain for the whole diet, because the weekly budget only works if most weeks actually land near it. Three practical checks:

  1. Look at the target, not the rate. If the aggressive rate puts the calorie target near the floor (1,500 kcal male / 1,200 kcal female on the standard setting), the deficit is being cut short anyway and the moderate rate will produce almost the same number with less strain. The floors page has the arithmetic.
  2. Match the rate to the training. Someone lifting hard with a specific strength goal has more reason to sit at 0.3–0.5%; someone with a lot to lose and no performance target can tolerate the higher end for a while, then step down.
  3. Judge it on the trend, not the scale. Three to four weeks of trend weight tells you what rate you are really achieving. If it is well under the setting, expenditure or logging has drifted — see why weight loss stalls — and the fix is usually not a faster setting.

The short version

Speed is a percentage of body weight: 0.3%, 0.5% or 0.75% per week, which for 75 kg is about 0.23–0.56 kg. The one athlete trial that compared speeds found the slower rate (0.7%) preserved and added lean mass where the faster one did not1. Pick the rate you can hold, watch the trend for a month, and let the percentage shrink the deficit as you go.

Educational overview only — not medical advice. Zyra is a training and nutrition tracking tool; the rates, caps and floors on this page describe how the calculator behaves, not what any individual should do.