Use the calorie deficit calculator to estimate the daily number of calories you need to reach your weight loss goals.

Whether you’re breathing, digesting food, or running a marathon, your body is continuously burning calories – units of energy. When you create a calorie deficit or eat fewer calories than your body needs, your body will use stored energy, usually fat, for fuel. 2 key factors are crucial to this process:

1. Basal metabolic rate (BMR)
2. Total daily energy expenditure (TDEE)

Basal metabolic rate (BMR)

Your basal metabolic rate is the minimum number of calories your body needs to maintain its basic functions such as breathing, blood circulation, and digestion, also known simply as your ‘metabolism’.

Your BMR accounts for around 60 to 75% of the calories you burn, making it an important factor in energy balance.

Total daily energy expenditure (TDEE)

Your TDEE builds on your BMR and includes all the calories you burn through the daily activities you participate in, like walking to work, exercising, and completing household chores. Combining your BMR and TDEE tells you how many calories you need to maintain your current weight.

The role of macronutrients during a calorie deficit

While a calorie deficit is important for weight loss, the quality of the calories you eat is equally important.

Macronutrients or carbohydrates, proteins, and fats, provide your body with energy and can support you during your weight loss journey.

By choosing healthier macronutrient sources, you can support your body to stay energised, maintain or build muscle, and better regulate your appetite, so you are less tempted to snack.

You can achieve a calorie deficit by eating fewer calories than you burn each day or increasing how much you exercise, or a combination of both.

Diet

Making changes to your diet, especially eating fewer calories or making healthier swaps is essential to creating a calorie deficit. Some of the things you can try include:

Avoid drinking extra calories through the consumption of drinks like alcohol and sugary drinks including fizzy sodas, fruit juices, and coffees. Instead, swap for fluids like water (try adding a slice of lemon or lime if you find it too bland), green or herbal tea, or hot water or tea with lemon.

Cut down on processed foods that are packed with calories and are designed to be attractive and encourage you to eat more, such as cakes, biscuits, pastries, sweets, and fast food. Research shows that a diet high in ultra-processed foods can result in a consumption of 500 more calories than a minimally processed food diet.

Make healthy swaps like swapping a sweet snack for a piece of fruit, like a banana or an apple, or savoury snacks such as crisps, for a handful of plain nuts and seeds. Cooking meals from scratch enables you to make healthy swaps and gives you greater control over your ingredients compared to shop-bought ready meals.

Manage your portion sizes by tracking your food intake with a daily food diary to prevent overeating or eating too many calories, which can lead to weight gain.

Exercise

Combining calorie restriction with increased exercise is likely to be the most beneficial way to encourage weight loss.

It is recommended that most adults aged 19 to 64 need to complete at least 150 minutes of moderate-intensity exercise (brisk walking, cycling, dancing, gardening) or 75 minutes of vigorous-intensity exercise (running, swimming, team sports, aerobics) each week. This should:

1. Be combined with strength training to work all your major muscle groups at least 2 days a week. Activities can include lifting weights, resistance band exercises, pilates, yoga, and exercises that use your body weight, like push-ups and sit ups.
2. Be spread out across 4 to 5 days a week, building in recovery days and alternating which muscle groups you work during each session.

You can also cut down the amount of time you spend sitting or lying down by breaking up periods of sedentary behaviour with physical activity.

Don’t cut too much protein from your diet

It’s important when you are trying to achieve a calorie deficit that you don’t cut too much protein, and other macronutrients, from your diet. Proteins have several important functions in the body, including:

• preserving or building muscle mass – if your protein intake is too low during a calorie deficit, your body may start breaking down muscle for energy, which you want to avoid
• supporting recovery – you’ll need protein to repair tissues, like muscle and bone, especially if you are exercising, so you can stick to your routine without risking injury or illness
• keeping you feeling satisfied after a meal – protein helps to keep you feeling full more than carbohydrates or fats, so good quality protein sources will reduce cravings and help you stick to your diet plan
• supporting healthy functioning – proteins are crucial for the production of important components in the body including hormones and enzymes that are needed to maintain your body’s normal functioning

When you are making changes to your diet, instead of cutting all protein from your diet, opt for high-quality sources like lean meat, oily fish, eggs, or plant-based options like legumes, tofu, edamame, or quinoa. If you do this, you’ll be supporting your weight loss journey and promoting your overall health.

Stay hydrated

Staying properly hydrated is important for managing a calorie deficit, not only to keep dehydration at bay but also for appetite regulation.

Thirst is often mistaken for hunger, resulting in eating more calories than you need, so drinking a glass of water before eating can help you feel full. Adequate hydration also supports your digestion and metabolism as well as helping your body to efficiently remove waste, improving your energy levels and generally making you feel healthier. The NHS recommends around 6 to 8 glasses of fluids per day, mainly consisting of water but this can also include tea and coffee.

How much weight should I aim to lose each week?

For sustainable weight loss, a safe and recommended rate is 0.5 to 1kg per week, alongside a calorie deficit of 500 to 1000 calories per day.

Drastic fast weight loss is not sustainable and can result in weight gain, whereas a slower approach helps to build healthy, long-term habits that are more sustainable and make it easier to reach your weight loss targets.

A calorie deficit offers several benefits for weight management and overall health. Some of the benefits are discussed below.

Weight loss and improved body composition

A calorie deficit of 500 calories per day equals 3500 calories per week, which can help you lose around 0.5kg per week – a safe and sustainable rate of weight loss. Over time, a calorie deficit like this can help you shed excess weight and support you to achieve a leaner, healthier physique.

Better understanding of energy balance and portion sizes

By managing your calorie intake, you’ll be more mindful of your food choices, portion sizes, and the balance between ‘calories in and calories out’.

Tracking your calorie intake will help you identify patterns in your portion sizes, food choices, and snacking habits that you may not have noticed before. This will help you to make smarter food choices and help to create a sustainable approach to eating.

Reduced risk of obesity-related conditions

Losing 5% of your initial body weight can improve your health if you are overweight or obese and lower the risk of developing conditions, including:

• heart disease
• high blood pressure
• diabetes
• liver disease
• kidney disease

Even modest weight loss can have a meaningful impact on your overall health and wellbeing. Weight loss achieved with a calorie deficit can help to reduce the pressure on your joints, improve your mobility, and lower the risk of obstructive sleep apnoea.

While a calorie deficit can encourage weight loss, it can carry risks if you don’t do it in a healthy and sustainable way.

Following a calorie deficit or a diet that’s overly restrictive increases the risk of:

• nutrient deficiencies because you may not consume the foods needed to provide essential vitamins, minerals, and protein
• muscle loss because if you do not have a sufficient energy intake, your body will break down muscle for energy, leading to weakness and reduced strength
• low bone density increasing the risk of fractures
• fatigue because you are not getting the nutrients or energy your body needs to sustain your energy and meet its demands
• hormone imbalances especially those that control your appetite, metabolism, fertility, and menstrual cycle
• illness or infection because you are not getting enough nutrients that support your immune system
• weight gain if you lose weight drastically over a short period and not in a sustainable manner, you risk weight gain because your body will not develop healthy, long-term habits, so you’re less likely to stick to healthy lifestyle changes

There are several possible reasons why you may not be losing weight even though you’ve reduced your calorie intake, including:

1. Inaccurate calorie tracking

You may be eating too many calories to support weight loss or you’re not eating enough to maintain your energy levels. Try keeping a food diary or using a calorie tracking app, so you can keep an accurate record of your daily calorie intake and spot any unhealthy patterns. Watch out for hidden calories that you may have missed out such as sauces, dressings, and oils.

2. Stress

Identify any stress triggers because stress can cause you to eat comfort food or engage in emotional eating. Stress also contributes to slowing our metabolism down which can impact our weight loss goals. If you can identify and avoid your stress triggers or practice mindfulness techniques, like yoga or breathing exercises.

3. Lack of sleep

Poor sleep increases our appetite and may increase our daily food intake. If you’re tired you may eat high-sugar foods for a quick burst of energy. Try to stick to a bedtime routine, like going to bed and waking at the same time each day, and promoting good sleep hygiene to encourage a better night’s rest.

4. You’ve hit a weight loss plateau

If you’ve been working out and restricting your diet for a while, you may have hit a plateau, so you may need to increase your exercise levels or eat fewer calories to compensate.

5. Lack of consistency

It’s important to remain consistent when you’re losing weight and following a calorie deficit. Make sure you complete your daily exercise and achieve your calorie deficit because fluctuations can stall your weight loss progress.

A calorie deficit is an important principle for weight loss and is the concept of eating fewer calories than you burn.

Maintaining a calorie deficit will support you on your weight loss journey but it’s important not to be overly restrictive and choose quality over quantity when it comes to food choices.

It’s important to lose weight steadily and sustainably, at a rate of around 0.5 to 1kg per week, to help you build healthy habits and encourage the weight to stay off. If you lose too much weight in a short space of time, there is a risk you will regain it and struggle to stick to your weight loss programme.

Can you gain muscle in a calorie deficit?

Yes, you can gain muscle while you are in a calorie deficit, particularly if resistance training is new to you or you have a high body mass index (BMI), but it will take careful planning and is usually more difficult than gaining muscle when there is a surplus of calories in your diet. Emphasis should be placed on the quality of your protein intake and the type of training you carry out.

Can I do a calorie deficit while pregnant?

No, you should not try to lose weight during pregnancy because it may not be safe and will not reduce the risk of complications. If you are overweight and pregnant, speak to your doctor or midwife for advice.

How can I track my calories?

There are many ways to keep track of your calories, including:

• keeping a written food diary
• using a calorie-counting app
• using a calorie deficit calculator to calculate how many calories your body needs
• getting calorie details from food labels or online databases

How long does it take to see calorie deficit results?

When you first embark on a weight loss journey, you’ll likely see rapid weight loss in the first 4 to 6 weeks, before it will slow down. That’s because in the first few weeks, you’ll be losing retained water, protein, glycogen, and a small amount of fat and muscle. Whereas, after this, you’ll be burning fat, and weight loss may take longer, you may need to adjust your calorie intake or physical activity levels to compensate during this time.