A calorie deficit occurs when you consume fewer calories than your body burns each day. Your body then uses stored fat as an energy source, which leads to weight loss over time. Creating a moderate calorie deficit through diet, exercise or a combination of both is one of the most effective and sustainable ways to lose weight.

The number of calories you should eat depends on factors such as your age, sex, height, weight and activity level. Our calorie deficit calculator estimates your daily maintenance calories and recommends a personalised calorie target to help you lose weight safely.

For most healthy adults, a daily calorie deficit of around 500 calories is considered a safe and effective starting point. This typically results in a weight loss of approximately 0.5 kg (1 lb) per week. However, nutritional needs vary between individuals, so it's important to avoid excessive calorie restriction.

Most healthcare professionals recommend aiming to lose between 0.25 kg and 1 kg per week. Losing weight gradually is generally more sustainable and may help preserve muscle mass while reducing the likelihood of regaining weight.

Yes. Weight loss is primarily achieved by maintaining a calorie deficit. While regular physical activity offers many health benefits and can increase the number of calories you burn, it is possible to lose weight through dietary changes alone.

Consuming too few calories for prolonged periods can lead to fatigue, nutrient deficiencies, muscle loss and a slower metabolic rate. Very low-calorie diets should only be followed under medical supervision.

Protein helps maintain muscle mass and can help you feel fuller for longer. Many people aiming to lose weight benefit from consuming around 1.2 to 1.6 grams of protein per kilogram of body weight per day, although individual requirements vary.

There are several possible reasons, including inaccurate calorie tracking, underestimating portion sizes, reduced physical activity, water retention or hormonal factors. Weight loss often isn't perfectly linear, so monitoring progress over several weeks provides a more accurate picture than daily weigh-ins.

Drinking enough water supports normal body function and may help some people manage their appetite. Replacing sugary drinks with water can also reduce overall calorie intake.

Foods that are high in protein and fibre are often more filling while being relatively lower in calories. Examples include lean meats, fish, eggs, beans, vegetables, fruit, low-fat dairy products and whole grains.

Yes. Carbohydrates do not prevent weight loss. What matters most is your overall calorie intake. Wholegrain carbohydrates, fruit, vegetables and legumes can all form part of a healthy calorie-controlled diet.

Tracking calories can help many people understand their eating habits and stay within their target intake. However, it isn't essential for everyone — some people prefer portion control, meal planning or mindful eating.

Intermittent fasting is simply one way of reducing calorie intake. The most effective approach is the one that helps you consistently maintain a calorie deficit while meeting your nutritional needs.

Prescription weight-loss medications such as Wegovy® and Mounjaro® work by reducing appetite and helping many people consume fewer calories more comfortably. Eligibility depends on factors including BMI and medical history, and treatment should only be prescribed following an appropriate clinical assessment.

Eligibility depends on your BMI, medical history and other clinical factors. In the UK, many adults with obesity, or those who are overweight with weight-related health conditions, may qualify for treatment.

Our calculator provides an estimate based on widely used equations, including the Mifflin-St Jeor Equation, together with the activity information you provide. It is designed as a guide and should not replace personalised advice from a healthcare professional or registered dietitian.

If you are pregnant, breastfeeding, under 18 years of age, have an eating disorder or have certain medical conditions affecting your metabolism or nutrition, you should seek advice from a healthcare professional before making significant changes to your diet or weight-loss plan.