A Note Before We Start
This article is general education, not a personal calorie target. If you have diabetes, kidney disease, frailty, an eating disorder, pregnancy, breastfeeding, or complex medical needs, ask for individual advice.
Last reviewed: 13 July 2026
One of the biggest traps with weight-loss medication is trying to eat the lowest number of calories possible. That is not what we want. Mounjaro may reduce appetite, but your body still needs nutrition.
Quick Answer
There is no single calorie target that is right for everyone. Your needs depend on your age, sex, height, weight, muscle mass, activity level, medical conditions and goals.
Most adults trying to lose weight need a modest calorie deficit, not starvation. Reduced appetite is expected. Poor nutrition is not.
What Is TDEE?
You may see online calculators called TDEE calculators. TDEE means Total Daily Energy Expenditure. It is an estimate of how many calories your body uses in a day.
That includes basic body functions, movement, exercise and digestion. A TDEE calculator can be a rough guide, but it is not exact. It should not become something to obsess over.
The Dr Mel Stance
Calories matter, but they are not the whole story.
The aim is not to hit the lowest number possible. The aim is to eat enough nourishing food while creating a sensible, sustainable calorie deficit.
What Does The NHS Say?
The NHS gives average maintenance figures of around 2,000 kcal a day for women and 2,500 kcal a day for men, but this varies depending on things like age, weight, height and activity level.
NHS Better Health explains that losing weight usually means using more energy than you take in, and suggests reducing intake by around 600 calories a day as a safe and sustainable approach for many adults.
These are general population guides. They are not personalised targets, and they do not mean you should ignore hunger, nutrition, side effects or medical advice.
Why Eating Too Little Can Backfire
Eating too little can make you feel worse and may make side effects harder to manage.
Your body may lose muscle as well as fat, especially without enough protein and strength work.
Very low intake can leave you weak, cold, dizzy or unable to concentrate.
Less food, less fibre and less fluid can slow the bowel.
Rapid weight loss, low protein, low iron or low overall intake can contribute.
You may miss vitamins, minerals, fibre and healthy fats.
Numbers can become stressful, especially if you start seeing eating as failure.
What Should My Plate Look Like?
Not every meal has to look exactly like this. It is a guide, not a test.
The Healthy Plate
Half vegetables or salad, one quarter protein, one quarter healthy carbohydrates, with a small amount of healthy fats and a drink.
The Small Appetite Plate
When appetite is low, the order matters. If you become full quickly, you have still prioritised what your body needs most.
Do Not Eat Less. Eat Smarter.
Instead of asking, “How little can I get away with eating?”, ask:
How can I give my body the nutrition it needs in the amount it now wants?
When To Ask For Advice
Speak to your prescriber, pharmacist, GP practice or dietitian if:
- you are regularly eating very little
- you cannot manage protein, fluids or basic meals
- you feel faint, weak, cold, shaky or unusually tired
- you are vomiting, have diarrhoea, or cannot keep fluids down
- you are losing weight very rapidly and feeling unwell
- calorie tracking is making you anxious, guilty or frightened of food
- you have a history of an eating disorder or disordered eating
Where To Read Next
Eating well
How to make every bite count when appetite is reduced.
Read nextProtein
Why protein matters for muscle, strength and small appetite days.
Read nextBuilding new habits
Use quieter appetite to build habits that support long-term health.
Read nextStarting Mounjaro
A calm first read on what to expect and when to ask for help.
Read nextSide effects
What is common, what helps and when to seek urgent advice.
Read nextDr Mel’s Notebook
Did you know?
Calories are units of energy, but food also provides protein, fibre, vitamins, minerals and fats your body needs to function.
Try this today
At your next meal, start with protein and vegetables before deciding how much carbohydrate you want.
The evidence
NHS guidance explains that calorie needs vary by age, weight, height and activity level, and that balanced meals and portion changes can also support weight loss.
Key Messages
- There is no magic calorie target for everyone.
- TDEE calculators can be a rough guide, but they are not exact.
- Most people need a modest calorie deficit, not starvation.
- Reduced appetite is expected. Poor nutrition is not.
- The plate becomes smaller, not less nutritious.
- Calorie awareness can be helpful. Calorie obsession is not the goal.
Useful Sources
NHS Better Health: Calories and weight loss
Last reviewed: 13 July 2026. Planned review: October 2026.