i
Set the target as a line.
Drop the daily figure from here into the app and the diary draws the line for you.
kcalThe UK calorie deficit calculator
Calorie deficit calculator. Your daily target, and the loss rate.
Type your details, pick a deficit, and see the daily calories to hit it, plus how much you would lose a week and a month at that pace.
Sex
Age (years)
Height
Weight
Activity level
Daily deficit
250 is gentle, 500 is the steady middle, 750 is faster but harder to keep up.
01The catch
A deficit you
can't see doesn't work.
The number is the easy part. The deficit only happens if what you actually eat lands under it, and untracked food is where deficits quietly disappear. NutraSafe puts the target on the diary and counts every meal against it.
ii
Count every meal against it.
Scan a UK barcode, search or photograph the plate. A live total tells you where you stand.
iii
Judge it on the trend.
The scale jumps day to day. The weekly line shows whether the deficit is real.
iv
Keep the protein up.
Macros plus 14 vitamins and 13 minerals against the UK NRV, so a lower-calorie week still covers you.
02Sizing the deficit
How big
should it be?
Bigger is not better. The right deficit is the largest one you can actually keep up.
250 a day, gentle
About a quarter-kilogram a week. Slow, but barely noticeable on the plate, so it is the easiest to sustain for months.
~0.23kg / week500 a day, steady
About half a kilogram a week, the common middle and the one the NHS rate as steady. A good default for most people.
~0.45kg / week750 a day, faster
About two-thirds of a kilogram a week. It works, but it is harder to hold and tends to cost more muscle and energy.
~0.68kg / weekThe floor
Don't drop below your BMR, the calories your body needs at rest. Long stretches under it are hard to sustain and not recommended.
03Frequently asked
Questions
people ask.
Answers sourced to the NHS and the standard energy-balance maths.
What is a calorie deficit?
Eating fewer calories than your body burns in a day. When you are in a deficit, your body makes up the gap by drawing on stored fat, which is how you lose weight. The size of the deficit sets how fast that happens.
How big should my calorie deficit be?
For most people a deficit of about 500 calories a day is the steady middle, losing roughly half a kilogram a week. 250 is gentler and easier to keep up. 750 is faster but harder to sustain and tends to cost more muscle. The NHS suggests aiming to lose 0.5 to 1kg a week. Avoid eating below your BMR for long stretches.
How much weight will I lose in a 500 calorie deficit?
Roughly 7,700 calories sit in a kilogram of body fat, so a 500 calorie daily deficit is about 0.45kg a week, near enough half a kilogram, or about 1.9kg a month. That is an average; water weight makes the scale jump around, so judge it over a month, not a day.
Can a calorie deficit be too big?
Yes. A very large deficit is hard to stick to, costs more muscle, leaves you tired, and often ends in a rebound. Eating below your BMR, the calories your body needs at rest, for long stretches is not recommended. A deficit you can keep up beats a bigger one you abandon.
Why am I in a calorie deficit but not losing weight?
Usually the deficit is smaller than it looks. UK labels are accurate only within 20 per cent, unweighed portions add error, and it is easy to undercount snacks and drinks. Water retention also hides fat loss on the scales. Weigh your food for a week, weigh in on the same day each week, and watch the monthly trend.
Aaron Keen is the founder of NutraSafe. He built this calculator on the Mifflin-St Jeor equation and the NHS guidance on a steady rate of loss, and checks the figures against the sources himself. About the research →
→More tools
The rest of the
calculators.
Free, no sign-up, sourced to the same UK guidance. Built and checked by the NutraSafe team.
You've set the deficit.
Now hold it.
Get NutraSafe on the App Store →
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