How Many Calories Should I Eat to Lose Weight UK?

The number of calories you need to lose weight depends on your body — specifically your total daily energy expenditure (TDEE), which is the total number of calories your body burns in a day. Creating a deficit below this produces fat loss. This guide covers how to calculate your TDEE, how large the deficit should be, and why calorie needs are different on GLP-1 medication.

Quick answer: To lose weight in the UK, aim for a daily calorie intake of 300–500 calories below your TDEE. For most women, this is 1,200–1,600 calories. For most men, 1,600–2,200 calories. Do not go below 1,200 calories (women) or 1,500 calories (men) without GP guidance. On Mounjaro, natural appetite suppression often produces these deficits without deliberate restriction — focus on protein quality rather than calorie counting.

How to calculate your TDEE

TDEE = Basal Metabolic Rate (BMR) × Activity Level Multiplier

Activity level	Multiplier	Description
Sedentary	1.2	Desk job, minimal 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	Heavy exercise 6–7 days/week

BMR estimates by weight (Mifflin-St Jeor)

Body weight	Approximate BMR (woman, 40 years old, 5ft 5in)	TDEE (sedentary)	Target for 0.5lb/week loss
14 stone (89kg)	~1,720 kcal	~2,064 kcal	~1,750 kcal
16 stone (102kg)	~1,870 kcal	~2,244 kcal	~1,900 kcal
18 stone (114kg)	~1,990 kcal	~2,388 kcal	~2,050 kcal
20 stone (127kg)	~2,120 kcal	~2,544 kcal	~2,200 kcal

The right size deficit

250 kcal deficit: ~0.5lb per week — sustainable, minimal hunger, minimal muscle loss
500 kcal deficit: ~1lb per week — the standard NHS recommendation for safe weight loss
750 kcal deficit: ~1.5lb per week — maximum recommended without specialist input
1,000+ kcal deficit: ~2lb+ per week — not recommended; increases muscle loss and metabolic adaptation significantly

On GLP-1 medication

Mounjaro and Wegovy naturally produce a 300–700 calorie daily deficit in most users through appetite suppression. On these medications, deliberate calorie counting is less critical — focus on protein quality and hitting minimum protein targets rather than precise calorie restriction.

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Frequently Asked Questions

How many calories should a woman eat to lose weight?

Most women need 1,200–1,600 calories per day to lose weight at 0.5–1lb per week, depending on height, current weight, age, and activity level. Do not go below 1,200 without medical guidance — this is the minimum for meeting basic micronutrient needs through food.

Is 1,200 calories enough to lose weight?

For smaller, sedentary women — yes, 1,200 calories creates a meaningful deficit. For most other people, 1,200 is too restrictive and produces muscle loss, fatigue, and metabolic adaptation. Calculate your TDEE and create a 300–500 calorie deficit from that number.