UK weight-loss calculator
Are you eating enough?
Most calculators are built to help you eat less. This one exists for the opposite problem, which is more common than it sounds.
Updated
I weigh st lb, I’m cm tall, I’m and . Most weeks I’m .
3blanks still to fill
Enter your details to see the energy your body uses at rest, and the intake below which this calculator will not go.
The problem nobody warns about
Every other tool on this site helps you find a deficit. This one is here because eating far too little is also a way for weight loss to go wrong, and it is easy to do without noticing when appetite drops sharply.
Your body uses energy before you move at all: breathing, circulation, staying warm, thinking. That figure is your basal metabolic rate, and it is usually the largest part of your day.
Sitting well below it for a long stretch is not a faster route to the same place. It is a different situation, and one that ought to involve someone qualified.
How this is calculated
BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161The floor shown is whichever is highest of your estimated resting need, a conventional minimum for your sex, and an absolute floor below which intake is considered very-low-calorie territory requiring supervision.
Important limitations
Where these figures come from
NICE defines a low-calorie diet as 800 to 1,200 kcal a day and recommends one only within a specialist weight-management service, and a very-low-calorie diet as under 800. That is why this calculator stops at 1,200 and produces nothing below 800. The 1,500 kcal figure for men is this site being more cautious than the guideline rather than following it: NICE gives no figure by sex. The resting-energy figure beside them comes from a published equation.
An estimated BMR is an estimate. Two people of the same height, weight, age and sex can differ meaningfully, and the equation was not derived on everyone.
If eating is difficult
If you are struggling to eat, or find that you cannot, that is worth raising with a healthcare professional rather than working around with a calculator. If your relationship with food or with your weight is causing you distress, Beat runs a UK helpline.
Related calculators
Frequently asked questions
Is it bad to eat below my BMR?
Briefly and occasionally, it is unremarkable. Consistently and for a long time, it is a situation that warrants proper oversight rather than a calculator, which is why this site will not recommend a target below your estimated resting need.
I am not hungry at all. Should I still eat?
Reduced appetite is an expected effect of some weight-loss treatments, and eating far less than your body needs for a sustained period is a reasonable thing to raise with your prescriber. This page can show you what the gap looks like; what to do about it is a clinical conversation.
Why will the calculator not give me a lower target?
Because a tool that will output any number you steer it towards is not a safety feature, it is a liability. Every calculator here clamps its recommendation at your estimated resting need and explains that it has done so, rather than quietly producing a figure that should not be followed.
Sources
- Overweight and obesity management (NG246), NICE
- A new predictive equation for resting energy expenditure in healthy individuals, American Journal of Clinical Nutrition
- Calories and weight loss, NHS Better Health
Important information
The calculators on this site provide general information and estimates. They are not medical advice and they do not diagnose any condition.
Everyone is different, and individual energy needs vary for reasons these equations cannot capture. If you have a health condition, take medication, are pregnant or breastfeeding, or have any concerns about your weight, speak to your GP, pharmacist or a registered dietitian.