Calorie Deficit for 1kg Per Week — The Complete NHS Guide 2026
Losing 1 kg per week is the upper limit of the NHS safe weight loss rate — achievable, effective, and for most overweight adults, significantly faster than the 0.5 kg/week floor. Knowing the exact calorie deficit for 1kg per week requires a personalised calculation based on your TDEE (Total Daily Energy Expenditure) — not a one-size-fits-all rule.
The fundamental mathematics: 1 kg of body fat contains approximately 7,700 kcal. To lose 1 kg per week (7 days), you need a daily calorie deficit of approximately 1,100 kcal. But whether that deficit is safe depends entirely on your TDEE — a sedentary 55 kg woman and an active 100 kg man have radically different daily calorie needs, and therefore radically different safe deficit possibilities. This is why our calculator uses the Mifflin-St Jeor formula to calculate your personalised TDEE first.
For a broader calorie deficit guide: Calorie Deficit Calculator NHS, what is a calorie deficit, daily calorie deficit guide, and safe calorie deficit guide.
🔥 The core calculation: Daily calorie target for 1 kg/week = Your TDEE − 1,100 kcal. If TDEE is 2,400 kcal: target = 1,300 kcal/day. The NHS minimum without medical supervision is 1,200 kcal (women) and 1,500 kcal (men). If the calculation produces a figure below these minimums, 1 kg/week may not be safe for you without GP supervision — the calculator checks this automatically.
How the TDEE Calculation Works
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn per day — at rest plus all activity. It is calculated in two steps:
Step 1: Basal Metabolic Rate (BMR)
BMR is the number of calories your body burns at complete rest — just to maintain vital functions (breathing, circulation, cell repair). Our calculator uses the Mifflin-St Jeor formula — the most accurate widely available BMR formula for most adults:
- Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
- Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Step 2: Activity Multiplier
TDEE = BMR × Activity Factor:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little or no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extremely active | × 1.9 | Very hard exercise, physical job |
Is a 1,100 kcal Daily Deficit Safe for Everyone?
No — and this is the critical nuance that generic "eat 1,500 calories a day" advice misses entirely. Whether a 1,100 kcal deficit is safe depends on your TDEE:
| Person | TDEE | 1 kg/wk Target | NHS Minimum | Safe? |
|---|---|---|---|---|
| Active 80 kg man | 2,800 kcal | 1,700 kcal | 1,500 kcal | ✅ Yes |
| Moderately active 75 kg woman | 2,200 kcal | 1,100 kcal | 1,200 kcal | ⚠️ Below minimum |
| Sedentary 60 kg woman | 1,700 kcal | 600 kcal | 1,200 kcal | ❌ Too low |
| Lightly active 90 kg woman | 2,100 kcal | 1,000 kcal | 1,200 kcal | ⚠️ Borderline |
| Active 95 kg man | 3,000 kcal | 1,900 kcal | 1,500 kcal | ✅ Safely above minimum |
⚠️ The NHS minimum rule: The NHS advises against going below 1,200 kcal/day for women or 1,500 kcal/day for men without direct medical supervision. If your TDEE-based target for 1 kg/week produces a figure below these minimums, the calculator recommends 0.75 kg/week instead — which produces a safe intake above the minimums for your TDEE.
How to Split the 1,100 kcal Deficit — Diet vs Exercise
The NHS recommends that the 1,100 kcal daily deficit comes from a combination of dietary reduction and increased physical activity — not from dietary restriction alone. Restricting calories only (without exercise) risks falling below nutritional minimums faster and losing lean muscle alongside fat.
A practical and sustainable split for a 1,100 kcal daily deficit:
- 600–700 kcal from food: Reduce calorie-dense foods, cut sugary drinks, reduce ultra-processed snacks and takeaways, and follow NHS Eatwell Guide portions
- 400–500 kcal from exercise: Approximately 45–60 minutes of moderate exercise daily (brisk walking, cycling, swimming). This meets and exceeds the NHS minimum of 150 minutes per week
This split is more sustainable than pure dietary restriction, preserves lean muscle mass, improves cardiovascular fitness, and produces better long-term weight maintenance outcomes. For more: safe rate of weight loss per week · 0.5–1 kg rule explained · why slow weight loss is better.
Practical Calorie Deficit Examples for 1 kg/Week
To make the numbers concrete, here are practical daily calorie targets for different profiles at the 1 kg/week rate:
| Profile | BMR | TDEE (moderately active) | 1 kg/wk Target | Suggested Split |
|---|---|---|---|---|
| Woman, 35, 75 kg, 165 cm | 1,535 | 2,379 | 1,279 kcal | Diet: 1,600 kcal + burn 321 kcal exercise |
| Man, 35, 95 kg, 178 cm | 1,990 | 3,085 | 1,985 kcal | Diet: 2,300 kcal + burn 315 kcal exercise |
| Woman, 45, 85 kg, 162 cm | 1,574 | 2,440 | 1,340 kcal | Diet: 1,700 kcal + burn 360 kcal exercise |
| Man, 50, 100 kg, 175 cm | 1,995 | 3,092 | 1,992 kcal | Diet: 2,350 kcal + burn 358 kcal exercise |
Common Mistakes When Trying to Lose 1kg Per Week
- Using a fixed "1,500 kcal/day" target: This number is meaningless without knowing your TDEE. For a sedentary woman with a TDEE of 1,700 kcal, 1,500 kcal is only a 200 kcal deficit — producing 0.18 kg/week, not 1 kg/week. For an active man with TDEE 3,000 kcal, 1,500 kcal is a 1,500 kcal deficit — too aggressive. Always calculate from your TDEE.
- Not accounting for exercise: Adding 400–500 kcal of exercise per day means you can eat more while maintaining the same deficit — protecting nutrition and muscle. People who rely on food restriction alone tend to hit nutritional minimums faster and lose more muscle.
- Cutting too many food groups: A 1,100 kcal daily deficit achieved through removing carbohydrates entirely typically results in massive initial water weight loss followed by a plateau — not sustained fat loss. The deficit should come from calorie reduction across food groups, not elimination.
- Weighing daily: Daily weight fluctuations of 0.5–2 kg are normal due to water, salt, and digestive content. These mask real fat loss. Weigh weekly at the same time and track the four-week trend.
- Applying 1 kg/week to everyone: As shown above, 1 kg/week is not safe for people with low TDEEs. Use the calculator to check whether 1 kg/week is right for you, or whether 0.75 kg/week is more appropriate.
Complete Tool Suite for Your Weight Loss Journey
Alongside the calorie deficit for 1 kg/week calculator, these free NHS-aligned tools support your complete journey:
- Calorie Deficit Calculator NHS — full TDEE calculator for any loss rate
- Weight Loss Timeline Calculator — how long to reach your goal
- Target Weight Date Calculator — is your target date safe?
- NHS Weight Loss Calculator — goal planning tool
- Visual BMI Calculator · Body Weight Visualizer · Height Weight Visualizer
- Ideal Weight Calculator UK · healthy weight range by height
- NHS BMI Chart · NHS healthy BMI range · BMI categories · healthy BMI weight guide
- NHS weight loss tips · how much per week safely · NHS vs CDC guidelines
- Blood Pressure Calculator NHS · blood pressure chart UK · QRISK Calculator NHS · signs of high blood pressure
- Water Intake Calculator NHS · water intake by age
- BMI education: BMI formula · how to calculate BMI · BMI equation vs calculator · BMI vs body fat % · what does my BMI look like
- Family: Child BMI Calculator NHS · Child Growth Chart UK · child growth percentiles · Percentile Calculator UK · Baby Weight Percentile UK · Height Percentile UK
- Fertility: Ovulation Calculator NHS · Pregnancy Due Date NHS · ovulation cycle explained · pregnancy due date explained
- General health: health weight ratios · what is QRISK score NHS
Frequently Asked Questions
To lose 1 kg per week, you need a daily calorie deficit of approximately 1,100 kcal (1 kg × 7,700 kcal ÷ 7 days). Your daily calorie target = your TDEE − 1,100 kcal. Use the calculator above for your personalised TDEE and exact daily target. For general calorie deficit guidance: Calorie Deficit Calculator NHS.
A 1,000–1,100 kcal daily deficit is at the upper end of the NHS safe range. It is safe as long as your daily calorie intake stays above the NHS minimums: 1,200 kcal (women) and 1,500 kcal (men). Whether this is achieved depends on your TDEE — the calculator above checks this automatically. For smaller adults with lower TDEEs, 0.75 kg/week (825 kcal/day deficit) is safer.
Step 1: Calculate BMR using Mifflin-St Jeor formula. Step 2: Multiply BMR by activity factor = TDEE. Step 3: Subtract 1,100 kcal from TDEE = daily target. Step 4: Check it is above NHS minimum (1,200/1,500 kcal). Step 5: Split deficit 60/40 between diet and exercise. The calorie deficit for 1 kg/week calculator above does all of this. See also: what is a calorie deficit.
No. For people with a low TDEE (e.g., a sedentary smaller woman), a 1,100 kcal deficit may drop daily intake below the NHS minimum of 1,200 kcal. In this case, 0.75 kg/week is the safer target. The calculator above checks this and recommends the safe option for your TDEE. For the underlying science: 0.5–1 kg rule explained.
TDEE (Total Daily Energy Expenditure) is the total calories you burn per day — BMR (at rest) × activity multiplier. Your TDEE determines how large a deficit any given intake creates. A 1,500 kcal diet creates a 500 kcal deficit for someone with TDEE 2,000 but a 1,000 kcal deficit for someone with TDEE 2,500. Personalised TDEE calculation is essential for accurate weight loss planning.
The NHS recommends a combination of both — not restriction alone. A practical split for a 1,100 kcal deficit: 600–700 kcal from reduced food intake and 400–500 kcal from exercise (~45–60 min/day). This protects nutritional adequacy, preserves lean muscle, and produces better long-term outcomes than diet-only restriction. For NHS exercise guidance: NHS weight loss tips.
Yes — the NHS recommends no more than 1 kg (2 lbs) per week without medical supervision. This is the upper limit, not the target. For most people, 0.75 kg/week is more sustainable and produces equally good long-term outcomes with lower metabolic stress. Read: how much per week safely and why slow weight loss is better.