Want to know how to lose weight in a week? 9 nutritionist tips to make a change

Here, a nutritionist explains how to lose weight in a week in a healthy and sustainable way

Woman eating from a bowl in kitchen, smiling, learning how to lose weight in a week
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If you're trying to learn how to lose weight in a week, it's natural to think fast diets and over-the-top workouts are the way forward. They've been sold to us as effective and worthwhile so well over the years that many people don't know they could be doing more harm than good. 

These plans often contain far fewer calories than adults need to function on a daily basis and they can create more problems than solutions in both the long- and short-term, contributing to struggles with healthy weight loss further down the line. 

It will always be better to lose weight over a shorter period of time, but whether you want to lose weight for an occasion or just make some lifestyle changes, there are steps you can take in a few days - like getting into a calorie deficit to lose weight - that can help you avoid classic weight loss mistakes and pivot towards a loss than stands the test of time.

How to lose weight in a week

A calorie deficit is the only way to lose weight in a week, studies by the Medical University of Vienna (opens in new tab) and Seoul National University (opens in new tab) explain. There are many diets that can allow you to achieve this deficit but burning more calories than you eat every day is the only way to lose weight, which is often why many people start dieting but can't lose weight

To work out your deficit, nutrition and performance coach Arj Thiruchelvam (opens in new tab) says, "Calculate how many calories your body needs in a day by taking your body weight in kg and multiplying it by 22 if you're female and 24 if you're male. Then multiply that figure by either 1.1 or 1.2, using the higher figure if you're fairly active," he suggests. "Then take off 500 calories to set your new daily calorie intake deficit figure and multiple that by 7 to reach your new weekly calorie intake goal."

The NHS (opens in new tab) suggests that 1 to 2lb per week (0.45 to 0.9 kg) is a safe rate of weight loss and to achieve this in the short term, you'd need to be at a loss of 3,436 to 3,752 calories per pound of weight you want to lose, according to leading research by Max Wishnofsky as published in the American Journal of Clinical Nutrition (opens in new tab). This means that if you want to lose 2lb during the week, you'll have to be in a deficit of between 6,872 and 7,504 calories - which is very severe. 

Multiple studies, including leading research from the Pennington Biomedical Research Center (opens in new tab), suggest that the body will adjust to the deficit over time and you'll stop losing weight - known as a weight loss plateau. They do confirm it works in the short term though, so if you're looking to learn how to lose weight in a week or even how to lose a stone in a month, this is what you need to know. 

Bowl of food with calorie counting app above the bowl to show how to lose weight in a week

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1. Track your calories

If you want to know how to lose weight in a week, then this is step one. Tracking how much you eat every day by calorific value will make sure you're not eating above this level, which is essential if you're looking to lose weight in a short space of time.  

"Start tracking your calories using an app which scans food labels," suggests Thiruchelvam. "Eat at a calorie deficit and track calories for short periods only to avoid excessive water retention and then revert to your maintenance level."

2. Avoid restrictive diets

Tracking calories shouldn't mean dramatically restricting, crash dieting, or changing your eating habits though. This is unsustainable behavior even over one week, explains nutritionist and wellbeing expert Jenna Hope (opens in new tab). "Initially, you may see the numbers dip on the scales but not fueling your body properly could leave you feeling sluggish, moody, nauseous, and run down," she says. Plus, you're a lot more likely to binge at the end of the week and undo whatever process you've made, another study by Pennington Biological Research Center (opens in new tab) confirms. 

This may be due to the fact that you’re cutting out major food groups, leading to nutrient deficiency. “Limiting specific foods or food groups can also often leave you wanting them more,” she says. This could increase sugar cravings, which may set you up for rebound weight gain after the week's up. 

"They may have an adverse effect on your weight in the long term and they may pose a risk to your mental wellbeing," she adds. 

Woman holding up a strainer full of spinach

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3. Add in nutritionally-rich foods

Don't get hung up on the ultra-processed foods you're cutting out, instead, focus on the nourishing foods you'll be adding in. “Incorporating more nutrient-dense foods into your diet can help to naturally displace some of the more 'unhealthy' foods that are high in sugars and unhealthy fats,” says Hope. 

But what exactly should you fill your plate with? Hope recommends adding one extra portion of vegetables into each meal, especially leafy greens like spinach and kale. As some of the best foods for weight loss, “they are rich in fiber and water, which will help you feel fuller for longer. They're also high in magnesium and iron to support your energy levels." 

Hope also suggests loading up on beans, which are also high in soluble fiber. As one of the key components of plans like the 80/20 diet rule, these can help fight inflammation and contribute to sustainable weight loss as they'll also keep you fuller for longer. “Try incorporating beans into Bolognese and stews to bulk them out and add them to soups and curries to ramp up protein and fiber too,” she suggests.

4. Do more exercise

When it comes to a calorie deficit and learning how to lose weight in a week, exercise is essential. You can enter the deficit through diet alone but it'll be much trickier than upping the exercise alongside changes in your diet, says Hope. "The combination of activity and consuming a healthy, balanced diet is the best way to support healthy, sustainable weight loss," she explains. 

But instead of trying to get onboard with HIIT treadmill workouts, opt for an activity that you love. "Exercise shouldn't feel like a punishment," the wellbeing expert says. "It's all about finding an activity that works for you." 

That could be walking for weight loss, taking a spin class with a friend, at-home workouts, or just going for a long walk. How much exercise you should do depends on how much weight you want to lose but the CDC (opens in new tab) suggests that everyone should do at least 150 minutes of moderate-intensity activity over one week. 

Bowl of chickpeas and hummus, one of the best snacks if you're learning how to lose weight in a week

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5. Choose healthier snacks

Knowing what to snack on when dieting is essential, Hope says. Eating between meals gets an unnecessarily bad rap but it's true that unhealthy snacks high in sugar and saturated fat are unlikely to contribute to your weight loss goals as they tend to be higher in calories than others. 

“Snacks can be a useful tool to manage blood sugar levels and prevent you overeating or craving high sugar foods later on in the day,” the nutritionist says. "High-sugar snacks will spike blood sugar levels and cause a consequent crash too."

As such, switching to high-protein snacks could help. “They will increase satiety and stabilize blood sugar levels," she adds. These include:

  • Cottage cheese on oatcakes 
  • Natural yogurt and cinnamon 
  • Carrots and cucumber sticks with reduced fat hummus 
  • Boiled eggs 
  • Apple with 1tsp of peanut butter
  • Roasted chickpeas 
  • Edamame beans

6. Stay well-hydrated

Drinking liters of water isn't going to make you automatically drop pounds but it will certainly make the short-term process of learning how to lose weight in a week easier. According to Humboldt University (opens in new tab), drinking water can increase the number of calories you burn as part of your resting calorie expenditure (the number of calories you burn outside of exercise) by up to 30% within the first 10 minutes. 

Not only that but drinking a glass of water can stop you from eating when you're not actually hungry. This is also one of the biggest intermittent fasting mistakes people make when they try to lose weight, so it's a very common problem. "When individuals are dehydrated, it's common to mistake thirst for hunger, which leads to overeating," says Hope. "Drinking enough water will also make sure that your kidneys can effectively filter toxins and waste, while retaining essential nutrients and electrolytes. A lack of water can lead to hard or lumpy stools and stop food from moving through your body properly, causing you to feel bloated and uncomfortable, which is hardly workout motivation."

To prevent this, Hope recommends drinking around two liters of water every day to help your digestive system run efficiently.

7. Eat more mindfully

The concept of mindful eating involves being fully engaged with what we are consuming, much like mindful drinking. “It also means we’re eating in response to our body’s physiological cues,” says Hope. 

Indeed, many of us make the mistake of munching on something during work or while watching TV, meaning our brains don't properly register what we've taken in. “Eating while distracted can impair digestion and the secretion of satiety hormones,” she explains. This means it can take longer for you to process that you’re full, which can lead to overeating. 

How to avoid this common pitfall? “Avoid engaging in other activities while eating and focus solely on the food on your plate,” suggests Hope. Try eating more slowly and not rushing meals, chew thoroughly, and focus on how the food makes you feel if you want to learn how to eat less. Listening to your body while you eat will help you acknowledge when you are full, which could lead to better portion control. 

8. Make small changes

If you’ve been eating healthy, balanced meals, but you’re still struggling to lose weight, it could be that you need to pay attention to the details. “When it comes to weight loss, focusing on the small things can make a big impact," says Hope. You may be eating a nutritious chicken salad, packed with lean protein, and your five-a-day, but your dressing choice might be sabotaging your efforts.

“Added sauces, dressings, sugar in tea and coffee, and high-calorie drinks can really add up,” notes Hope. She recommends opting for vinegar-based dressings over sugary, bottled options or sauces, limiting the sugar in your tea and coffee, and switching high-calorie, sugary alcoholic drinks for water or the lowest calorie alcohol instead if you want to drink.  “These small changes will make a big difference over time,” she adds.

Healthy snacks in box, including blueberries and quinoa salad

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9. Find better alternatives

Contrary to popular belief, you don't need to part ways with your favorite foods to lose weight if you want to know how to lose weight in a week. You can swap out certain higher-calorie choices for lower-calorie foods that have additional health benefits, suggests Hope. If you're a particularly big bread fan, for instance, there's no need to give up this lunchtime staple - just opt for sourdough instead. 

“Sourdough undergoes a fermentation process, which helps break down the gluten proteins and, as a result, can leave you feeling less bloated than regular bread,” explains Hope. It is also a good source of fiber, which is significantly more filling than other macronutrients, apart from protein, a study by Inland Norway University of Applied Sciences (opens in new tab) explains. 

Should you try and lose weight in a week?

It is possible to learn how to lose weight in a week but that doesn't mean you should, says Jenna Hope. "There are so many quick fixes out there that promise you a certain amount of weight loss within a short period of time. However, often the faster you lose weight the more likely you are to put it back on." 

Any weight you do lose is also unlikely to be fat, rather water weight or muscle mass. A study by Ahvaz Jundishapur University of Medical Sciences (opens in new tab) found, for instance, that those who lost 5% of their body weight over 5 weeks through a calorie deficit lost less body fat and more muscle mass and water weight overall compared to those who lost the same amount of weight over 15 weeks. Scaled down to one week alone, it's unlikely that whatever weight you do lose will make much of a difference.

It's not only your weight that you may have to worry about though, as the body isn't designed to go through a period of rapid weight loss. "Some of the consequences that losing weight quickly can have on the body include gallstones, which occurs in 25% of people who lose weight quickly, dehydration, and of course, malnutrition," she says. "This can all lead to further side effects, including dizziness, recurring headaches, hair loss, fatigue, and constipation to name a few."

Hope suggests that you should only be making incremental changes during this time and instead, use the week to start making healthy changes for the coming months.

Phone with step count showing, next to green smoothie

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How to lose weight in a sustainable way

Losing weight sustainably is all about combining a healthy diet with consistent exercise, says Hope, offering the plan below to those looking to change their eating habits. "It should only be used as a guide,” she says. “It’s important to mix up your diet on a regular basis and incorporate a wide variety of foods week on week.” 

What to eat for breakfast

You activate the thermogenesis process which stimulates your metabolism when you eat breakfast, research by the University of Worchester (opens in new tab) explains. However, what you choose for breakfast is important, particularly if you are aiming to lose weight. 

Hope recommends consuming some protein and fiber-rich foods to keep your blood sugar levels stable and stop you hankering after a high-sugar snack at 10 am. Some good choices include...

  • Porridge with cinnamon and berries
  • Green smoothie with banana, Greek yogurt, spinach, oats and cinnamon
  • Seeded sourdough toast topped with two scrambled eggs, spinach and mushrooms
  • Scrambled tofu with onions and peppers
  • Greek yogurt with muesli and berries
  • Spinach, mushroom and tomato omelet
  • Baked eggs with eggplant, peppers and spinach

What to eat for lunch

If your stomach is rumbling come 1pm, it can be tempting to grab the first thing you see in the fridge. But opting for a nutritionally balanced meal can make a big difference when it comes to losing weight. 

Choose a source of protein - think beans, eggs, fish, or chicken - and brightly colored vegetables. 


  • Minestrone soup
  • Vegetable omelet
  • Roast chicken salad
  • Tuna salad and wholegrain wrap
  • Brown rice goodness bowl with avocado, roasted zucchini and eggplant, low-fat hummus and roasted chickpeas.
  • Jacket sweet potato with tuna and sweetcorn
  • Cauliflower and chickpea soup

What to eat for dinner

It’s crucial you don’t skip dinner or just opt for a bowl of sugary cereal. Research from Osaka University (opens in new tab) found that while missing the one-off meal wasn't going to cause any damage, those who skipped dinner were more likely to gain weight in the future or be overweight. 

Eating a nutritious evening meal is also linked to a restful slumber - by allowing the brain to produce neurotransmitters to calm the mind and induce sleep - and it also encourages you to make better choices at breakfast and lunch the next day by maintaining stable blood sugar levels overnight.

  • Prawn stir-fry
  • Grilled salmon with broccoli, asparagus and sweet potato
  • Quinoa salad with roasted vegetables and a tahini dressing
  • Creamy green pea and broccoli soup with sourdough croutons
  • Sea bass or tofu traybake with parsnips, green beans and onions
  • Turkey burgers served with butternut squash mash, broccoli and cauliflower
  • Black bean and mince meatballs in tomato sauce served with quinoa
Grace Walsh
Health Editor

A digital health journalist with over five years experience writing and editing for UK publications, Grace has covered the world of health and wellbeing extensively for Cosmopolitan, The i Paper and more.

She started her career writing about the complexities of sex and relationships, before combining personal hobbies with professional and writing about fitness. Everything from the best protein powder to sleep technology, the latest health trend to nutrition essentials, Grace has a huge spectrum of interests in the wellness sphere. Having reported on the coronavirus pandemic since the very first swab, she now also counts public health among them.