Calorie Deficit for 0.5kg Per Week
Complete Guide & Calculator (2026)

What Calorie Deficit Do You Need to Lose 0.5kg Per Week?

The short answer: approximately 500 kcal below your TDEE (Total Daily Energy Expenditure) every day. This is because 1 kg of body fat stores approximately 7,700 kcal of energy, so losing 0.5 kg of fat per week requires a weekly deficit of 3,850 kcal — roughly 550 kcal/day, which most sources and clinical guidelines round to 500 kcal/day as the standard recommendation.

The 500 kcal/day deficit for 0.5 kg/week loss is precisely the NHS lower safe limit for weight loss. It sits at the safer, more sustainable end of the NHS-recommended range of 500–1,000 kcal/day (which produces 0.5–1 kg/week loss). This guide covers everything you need to know about this specific rate: the physiology, how to calculate your personalised target, practical strategies, and why this rate may actually be the most effective long-term choice despite being the "slower" option.

The Maths Behind 0.5kg Per Week

Understanding the arithmetic removes guesswork and builds confidence in the approach. Here is the full working:

• 1 kg of pure body fat ≈ 7,700 kcal of stored energy
• 0.5 kg of fat = 0.5 × 7,700 = 3,850 kcal total deficit needed per week
• 3,850 ÷ 7 days = 550 kcal/day (commonly rounded to 500 kcal/day in clinical practice)

In practice, the 500 kcal/day figure is slightly conservative — which is actually helpful, because weight loss in the real world is never perfectly linear. Some days will see more or less deficit than planned. A slightly conservative target builds in a small buffer against tracking errors and daily variation.

It is also worth noting that the 7,700 kcal/kg figure applies to fat tissue specifically. Early weight loss (weeks 1–2) typically exceeds 0.5 kg per week because glycogen (stored carbohydrate) and its bound water are also depleted — contributing approximately 1–2 kg of rapid loss before true steady-state fat burning. From week 3 onwards, the rate settles to reflect genuine fat loss at your deficit.

How to Calculate Your Personalised Calorie Deficit for 0.5kg/Week

The calculator above does this automatically, but here is the manual method using the Mifflin-St Jeor formula (the most accurate widely-used BMR formula):

Step 1: Calculate Your BMR

Step 2: Multiply by Activity Factor (TDEE)

Step 3: Subtract 500 kcal for 0.5kg/Week Loss

Continuing the example: lightly active TDEE of 1,994 kcal − 500 = 1,494 kcal/day target. This is safely above the NHS minimum of 1,200 kcal/day for women. Result: approximately 0.5 kg per week fat loss.

Step 4: Check Against NHS Minimum Intake

Before finalising, verify your intake target stays above NHS minimum thresholds: 1,200 kcal/day for women and 1,500 kcal/day for men. For most adults with a TDEE above 1,700 kcal, a 500 kcal deficit comfortably clears these minimums. If you have a low TDEE (common in shorter, older, or very sedentary women), recalculate with our safe calorie deficit guide.

Why 0.5kg Per Week Is Often the Best Choice

It might seem counterintuitive that the NHS's lower safe rate is often the better practical choice. But there are strong evidence-based reasons why losing 0.5 kg/week outperforms faster approaches over a 6–12 month period for many people:

• Superior muscle preservation: At a 500 kcal deficit, lean muscle loss is minimal — particularly when combined with adequate protein and resistance exercise. At larger deficits, the proportion of muscle lost increases substantially, reducing basal metabolic rate and making weight maintenance harder.
• Better metabolic rate maintenance: Aggressive calorie restriction triggers metabolic adaptation — the body reduces its energy expenditure beyond what weight loss alone explains. A 500 kcal deficit produces significantly less metabolic adaptation than larger deficits, keeping the weight loss process efficient for longer.
• Higher adherence rates: A 500 kcal daily deficit is manageable on most days without extreme hunger, deprivation, or social disruption. Adherence over 20+ weeks at 500 kcal/day produces more total fat loss than 6 weeks at 1,000 kcal/day followed by diet abandonment and weight regain.
• Better hormonal environment: Severe restriction suppresses leptin (satiety hormone) and elevates ghrelin (hunger hormone) far more aggressively than moderate restriction. This makes hunger progressively worse with larger deficits — often leading to binge-restrict cycles.
• Sustainable habit formation: At 500 kcal below TDEE, you can generally still socialise, enjoy meals, and build the long-term dietary habits that prevent weight regain — which is the part of weight management that most people fail at.

Read the full evidence base in our guide on why slow weight loss is better and the 0.5–1 kg rule explained.

Practical Strategies to Achieve a 500 kcal Daily Deficit

There is no single correct way to create a 500 kcal daily deficit. The best approach is the combination of strategies you can sustain consistently over months. Here are the most effective, NHS-aligned options:

Dietary Changes (Creating 300–400 kcal of Deficit)

• Reduce dinner portion sizes by 20–25%: For most people eating typical UK meals, this creates 150–300 kcal savings per day without changing what you eat — only how much.
• Eliminate liquid calories: Swapping two daily sugary drinks, fruit juices, or large lattes for water, black coffee, or herbal tea saves 200–500 kcal — often all the deficit needed.
• Follow the NHS Eatwell Guide plate model: Half vegetables/fruit, quarter wholegrains, quarter lean protein. This naturally reduces calorie density while increasing satiety through volume, fibre, and protein.
• Front-load protein at breakfast: High-protein breakfasts (eggs, Greek yoghurt, cottage cheese) reduce hunger across the rest of the day by stabilising blood glucose and appetite hormones.
• Reduce ultra-processed food: Cutting one packet of crisps, one chocolate bar, or one large biscuit saving typically 150–250 kcal per item eliminated.

Activity Changes (Creating 150–250 kcal of Deficit)

• Walk 8,000–10,000 steps daily: Burns approximately 250–350 kcal — contributing directly to the deficit while improving cardiovascular health.
• NHS 150-minute weekly exercise target: 30 minutes of brisk walking, cycling, or swimming five days a week. This creates an additional 200–300 kcal of daily deficit on exercise days.
• Resistance training 2–3 times/week: Builds lean muscle which elevates basal metabolic rate — making future fat loss progressively more efficient.

Common Mistakes When Targeting 0.5kg Per Week

Even with the right calorie target, these are the most common reasons people don't achieve the expected 0.5 kg/week loss:

• Underestimating intake by 20–40%: Research consistently shows people underreport food intake significantly without tracking. Even brief food diary periods (2–4 weeks) dramatically improve accuracy.
• Overestimating exercise burn: Gym machines and fitness trackers overestimate calorie burn by 15–30%. "Earning" meals through exercise often eliminates the deficit entirely.
• Expecting linear progress: Weight fluctuates ±1–2 kg daily based on water retention, hormones, bowel content, and sodium intake. Weigh weekly (same day, same time, same conditions) rather than daily to see the true trend.
• Not recalculating as weight falls: Every 3–5 kg of weight loss reduces TDEE by approximately 50–100 kcal. After significant loss, recalculate to ensure the deficit is still ~500 kcal. Use the calculator above with your new weight.
• Treating the first two weeks as representative: Initial loss is inflated by water and glycogen depletion. True fat loss rate becomes visible from week 3–4.
• Too little protein: Consuming under 0.8 g/kg/day of protein during a deficit leads to disproportionate muscle loss — which reduces basal metabolic rate and slows future fat loss.