• Best Exercises

• How It Works

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Based on the Mifflin-St Jeor Equation for BMR. Please note:• Exercise is 15 to 30 minutes of elevated heart rate activity
• Intense exercise is 45 to 120 minutes of elevated heart rate activity
• Very intense exercise is 2+ hours of elevated heart rate activity

Why use a weight loss calculator?

A calorie deficit is when you consume fewer calories than your body uses to maintain its current weight. This deficit results in loss of energy stores, including fat, leading to weight loss. Our weight loss calculator works out how many calories you need to lose weight at a healthy, sustainable rate. We also give advice on different weight loss treatments.

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How does the calorie deficit calculator work?

Our calorie deficit calculator and the advice on this page is designed for UK patients. It uses a scientifically proven formula to calculate how many calories your body needs each day based on your age, height, weight, sex, and activity level. This is important because if you want to lose weight, you need to eat fewer calories than your body burns – this is called a calorie deficit.

The Mifflin-St Jeor Equation

We use the Mifflin-St Jeor Equation to calculate your Basal Metabolic Rate (BMR). BMR is the number of calories your body needs to function at rest – just breathing, digesting food, and keeping your heart beating. The Mifflin-St Jeor formula is one of the most accurate ways to estimate your BMR.Here’s how it works:• For men: BMR = 10W + 6.25H – 5A + 5• For women: BMR = 10W + 6.25H – 5A – 161Where:• W is your weight in kilograms
• H is your height in centimetres
• A is your age in yearsOnce we know your BMR, we multiply that number by an activity factor (like 1.2 if you don’t exercise much, or 1.75 if you’re very active). This gives us your total daily energy expenditure (TDEE), which is how many calories you burn in a typical day.

What about other equations?

You might have heard of other formulas like the Harris-Benedict Equation or the Katch-McArdle Formula. These equations are still used, but they have their own quirks.• Harris-Benedict Equation. This was one of the first formulas used to calculate BMR, but it’s a bit outdated now. It was updated in the 1980s but has been replaced by more accurate methods like the Mifflin-St Jeor Equation.• Katch-McArdle Formula. This one is more advanced because it takes into account your lean body mass (how much of your weight is muscle versus fat). It’s really helpful if you know your body fat percentage, but most people don’t have that info, which makes it harder to use.We’ve chosen the Mifflin-St Jeor Equation because it’s accurate for the majority of people and easy to use. You don’t need any special measurements like body fat percentage, and it works well for both men and women.

Creating a calorie deficit

Once we calculate your TDEE (the calories you need to stay the same weight at your current activity levels), we help you create a calorie deficit. If you want to lose 1 pound a week, you need to eat about 500 fewer calories per day. For example, if your TDEE is 2,500 calories, eating 2,000 calories a day would create a 500-calorie deficit, leading to weight loss over time.Here’s the maths:• 1 pound of body weight = 3,500 calories
• To lose 1 pound in a week, you need to create a 3,500-calorie deficit over 7 days (which is 500 calories per day).

Keeping it safe and healthy

It’s important not to drop your calorie intake too much. If you cut more than 1,000 calories per day, it can lead to muscle loss, tiredness, and might slow down your metabolism. Losing more than 2 pounds (about 1kg) per week can also be hard to keep up, and in some cases, you might even end up gaining the weight back later.Eating too few calories can also make it harder for your body to get the nutrients it needs, so even when creating a calorie deficit, it’s important to eat balanced meals that give your body the vitamins and minerals it needs to stay healthy.

Why exercise helps

In addition to reducing your calorie intake, adding exercise to your routine helps burn even more calories. This means you don’t have to cut as many calories from food alone. Plus, exercise is great for your overall health and can help build muscle, which actually helps burn more calories even when you’re at rest.

High calorie foods to be aware of

When managing a calorie deficit, it's important to be mindful of high-calorie foods that can add up quickly. However, many of these foods - like almonds and avocados - are packed with healthy fats and nutrients, so you don’t need to avoid them altogether. Just watch your portion sizes and prioritise whole, non-processed, foods.

Low calorie foods to help you stay full

Staying full while eating fewer calories is key to maintaining a calorie deficit, and ensuring you enjoy your new diet. These low calorie foods are nutrient-dense and can help keep you satisfied without going over your daily calorie limit.

What exercise burns the most calories?

Burning calories efficiently is key to achieving your weight loss goals, and different exercises burn calories at varying rates. Factors like body weight, intensity, and duration all play a role in how many calories you burn. Here’s a comprehensive list of exercises, from high-intensity to low-impact, along with their estimated calorie burn rates.

Running (high intensity)

~600–900 calories per hour (based on speed and body weight). Running, especially at a fast pace, is one of the most effective calorie-burning exercises. Sprinting or distance running engages multiple muscle groups and boosts heart rate rapidly.

Cycling

~500–1,000 calories per hour (depending on speed and intensity). Cycling offers an excellent cardiovascular workout. You can adjust intensity by increasing your speed or resistance, whether on a stationary bike or outdoors.

Swimming

~400–700 calories per hour. Swimming works nearly every muscle group in your body, providing a full-body workout. Different strokes burn varying amounts of calories, with the butterfly stroke typically burning the most. Swimming also has the benefit of being kind to your joints, so a great option for exercise at any age.

High-Intensity Interval Training (HIIT)

~600–900 calories per hour. HIIT involves alternating between short bursts of high-intensity exercises and brief rest periods. It keeps your heart rate elevated and increases your calorie burn even after the workout, known as the "afterburn effect".

Skipping rope

~600–800 calories per hour. This simple yet powerful workout is a full-body exercise that burns a lot of calories in a short time, improves your coordination, and builds your endurance. A rope can be packed into a small case, making it perfect for exercise whilst travelling.

Rowing

~500–700 calories per hour. Rowing engages your back, shoulders, arms, and legs, making it an excellent full-body workout that’s low-impact but highly effective at burning calories.

Elliptical trainer

~400–600 calories per hour. The elliptical provides a low-impact cardio workout that targets both the upper and lower body. It's easier on the joints compared to running but still burns substantial calories.

Hiking (with elevation)

~400–600 calories per hour. Hiking on an incline or uneven terrain increases the challenge and calorie burn while being a low-impact, enjoyable activity for many people.

Stair climbing

~500–700 calories per hour. Climbing stairs works your lower body muscles intensely, and it’s a great way to burn calories quickly. This can be done with a stair machine or actual staircases.

Boxing (sparring)

~600–800 calories per hour. Boxing sparring sessions are intense, engaging your core, arms, and legs, and keeping your heart rate high throughout the session.

Aerobic dance (Zumba, Dance Fitness)

~400–600 calories per hour. Aerobic dance workouts combine coordination and strength in a fun way, keeping your heart rate elevated while burning a significant amount of calories.

CrossFit

~500–700 calories per hour. CrossFit combines weightlifting, aerobic conditioning, and functional movements. The intensity of CrossFit workouts leads to high calorie burn and improved muscle strength.

Basketball

~400–600 calories per hour. Playing basketball involves constant movement, quick sprints, and jumping, which increases your heart rate and burns calories quickly.

Tennis

~500–700 calories per hour. Tennis, especially singles play, involves a lot of running, quick lateral movements, and power in every stroke, making it a fun and high calorie-burning sport.

Football

~600–800 calories per hour. Football requires a lot of running, sprinting, and fast-paced movements, which makes it one of the highest calorie-burning team sports.

Rock climbing

~500–700 calories per hour. Rock climbing challenges your upper and lower body strength, while also requiring endurance. The more difficult the climb, the more calories you burn. It's a great outdoor activity that is often done in groups, so has a social elements to benefit mental health.

Martial arts (Judo, Karate, Taekwondo)

~500–800 calories per hour. Martial arts combine explosive movements, coordination, and endurance, providing a great workout that targets both cardio and muscle strength.

Weightlifting (circuit training)

~300–500 calories per hour. Although traditional weight lifting doesn’t burn as many calories as cardio, doing circuit training (a combination of resistance exercises with little rest in between) increases the overall calorie burn.

Volleyball

~300–450 calories per hour. While not as intense as some other activities, volleyball keeps you moving, jumping, and diving, which still burns a fair number of calories. It's practised in small teams, so is an opportunity to meet new people.

Walking

~200–400 calories per hour. Walking at a brisk pace is a low-impact but effective way to burn calories, especially for beginners or those looking for a gentle exercise.

Yoga

~200–400 calories per hour. Power yoga can increase calorie burn by combining flexibility, strength, and endurance, while also improving mental focus and relaxation.

Pilates

~200–300 calories per hour. While not as cardio-intensive as other activities, Pilates strengthens your core and increases flexibility, leading to fat burning, muscle toning and joint health.

Calorie deficit calculator UK FAQs

What is a calorie deficit?

A calorie deficit is when you eat fewer calories than your body needs to maintain its current weight. In a calorie deficit, you’re giving your body less energy than it needs, so it burns stored fat for fuel. This is how you lose weight over time.

How do you work out calorie deficit?

To work out a calorie deficit, you first need to know how many calories your body needs just to stay the same weight (this is called your maintenance calories). Then, you eat fewer calories than that number. Our calorie deficit calculator helps you figure out exactly how many calories you should eat based on your age, height, weight, gender, and activity level.

How accurate is the calorie deficit calculator?

Our calorie deficit calculator is designed by experts and uses proven formulas to give you accurate results. However, it’s still an estimate - everyone’s body is a little different, so you might need to tweak your calories slightly over time to find what works best for you.

How many calories should I eat a day?

The number of calories you should eat a day depends on things like your age, sex, activity level, and weight goals. For example, teenagers and active people usually need more calories than adults who aren’t as active. Our weight loss calculator is designed for UK patients and can help you find the right number based on your details.

What calorie deficit is recommended for weight loss?

For safe and steady weight loss, most people aim for a calorie deficit of around 500-1,000 calories per day. This usually results in losing about 1-2 pounds (0.5-1 kg) a week. It’s a good pace because it helps you lose weight without feeling super hungry or tired all the time.

Can I use this calorie deficit calculator for weight maintenance?

Yes, you can. If you don’t want to lose weight but just want to stay the same, the calculator can show you how many calories you need to maintain your current weight. Just make sure to follow the maintenance calorie number instead of the deficit.

What’s the safest rate of weight loss?

The safest rate of weight loss is about 1-2 pounds (0.5-1 kg) per week. Losing weight faster than this might not be healthy and can make it harder to keep the weight off in the long run. It’s always better to take things slow and steady.

Can you build muscle in a calorie deficit?

It’s tricky, but yes, you can build muscle while in a calorie deficit. It’s easier if you’re new to strength training or if you’re overweight. You’ll need to eat enough protein and focus on resistance exercises like weightlifting. However, building a lot of muscle is harder when you’re eating fewer calories.

Why am I not losing weight in a calorie deficit?

If you’re not losing weight in a calorie deficit, it could be because of a few reasons:
• You might not be tracking your calories accurately.
• You could be underestimating portion sizes or forgetting to account for snacks or drinks.
• Stress, lack of sleep, or other factors can slow down your progress. Sometimes it takes a little while for the body to adjust, so be patient and stay consistent.

Medically reviewed

This page was last medically reviewed by Dr Adam Abbs on 15 October 2024.At Weight Loss Calculators, we are dedicated to offering you the most reliable and up-to-date health information available. Our content is routinely reviewed and updated based on the latest medical research and clinical guidelines.

Dr. Adam Abbs, MBBS FRCGP PGCCE FHEA

Dr Adam Abbs is an experienced GP trained in the NHS, with a special interest in digital health, remote consultations, and personalised healthcare, particularly in weight management. Dr Abbs has been a driving force in improving access to safe, high-quality healthcare through innovative digital solutions. His expertise extends to writing and educating on remote healthcare, with his RCGP-accredited Remote Consultation Handbook published in 2020.GMC Number: 7078829