Want to know how to lose weight in a week? A nutritionist gives their expert take

If you’re wondering how to lose weight in a week, here’s everything you should consider first, according to a nutritionist

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If you want to know how to lose weight in a week, it's natural to turn towards fast diets and over-the-top exercise regimes. They've been sold to us for years as effective and worthwhile by everyone from celebrities to supposedly doctor-approved companies.

But 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 the short-term, contributing to struggles with healthy weight loss down the line.

Whether you want to lose weight for an occasion or just start making some lifestyle changes, there are steps you can take in just a few days—like getting in a calorie deficit to lose weight and finding out which diet works best—to lose some water weight and pivot towards a loss that stands the test of time. 

Is it possible to lose weight in a week?

Yes, if you get into a calorie deficit then it's possible to lose weight in just one week. The NHS suggests that a safe rate of weight loss is between 0.45 to 0.9 kg, translating to around 1 to 2lb per week. However, there are some factors to consider.

To achieve this rate of weight loss in the short term, you'd need to be in a deficit of between 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 won't work in the longer term as the body will adjust to the deficit and you'll stop losing weight fairly quickly, but evidence from multiple sources including Pennington Biomedical Research Center (opens in new tab) suggests that it will work over a limited period of time. 

The weight loss is unlikely to be fat, however, and more likely to be water weight or muscle mass. A study conducted by Ahvaz Jundishapur University of Medical Sciences (opens in new tab) found 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 the loss will make much of an impact. 

Any weight you can lose will also be dependent on a number of other factors along with your deficit, including the weight you started at, age, and gender. The best way to determine how much weight you'll be able to lose is to use the National Institutes of Health (NIH) Body Weight Planner (opens in new tab)

So while it's possible to learn how to lose weight in a week, it's a difficult process. The best way to lose weight is over a sustainable period of time, says nutritionist Jenna Hope. "There are so many quick fixes out there that promise you a certain about 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."

Losing weight quickly can also trigger a number of health issues, with tiredness and irritability common in the short-term and malnutrition and gallstones becoming a problem later on. 

"Some of the consequences that rapid weight loss can have on the body include gallstones, which occurs in 25% of people who lose weight quickly, dehydration, and of course, malnutrition," James Bickerstaff, qualified nutrition coach at OriGym Centre of Excellence, says. "This can all lead to further side effects, including dizziness, recurring headaches, hair loss, fatigue, and constipation to name a few."

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

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How to lose weight in a week? 8 things you need to know

1. Avoid restrictive diets

“Restrictive diets often come with extensive promises, so it can be tempting to jump into one,“ acknowledges Hope. “However they are not only unsustainable—and therefore may have an adverse effect on your weight in the long term—but they also pose a risk to your mental wellbeing.” 

Initially, you may see the numbers dip on the scales, but not fuelling your body properly could leave you feeling sluggish, moody, nauseous, and run down. 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.

2. Add in nutritionally-rich foods

Don't get hung up on the ultra-processed foods you're cutting out—and 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. As some of the best foods for weight loss, “they are rich in fiber and water, which will help you feel fuller for longer,” she explains. Aim for leafy greens, which are packed with magnesium and iron to help support your energy levels—particularly great if you often feel tired in winter and when coming into spring.

Hope also suggests loading up on beans, which are high in soluble fiber. As one of the key components of plans like the 80/20 diet rule, these can help fight inflammation and they aid healthy, sustainable weight loss. “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 advises.

3. Tweak your snacks

Eating between meals often gets a bad rap but it's true that unhealthy snacks aren‘t really conducive to healthy, sustainable weight loss. More nutritious alternatives could be added instead. “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,” says Hope. 

However, which ones you choose is important. “High-sugar snacks will spike blood sugar levels and cause a consequent crash,” she says. “When blood sugar levels fall, you’re more likely to crave sugar.” 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

4. Stay well-hydrated

Believe it or not, not sipping on enough water could play a part in not only preventing weight loss, but aiding in weight gain. “When individuals are dehydrated, it’s common to mistake thirst for hunger, which can lead to overeating,” explains Hope. Drinking a glass of water can fill up your stomach, leading to a sense of fullness. Your stomach will then send signals to your brain to tell it to stop eating. 

Additionally, staying hydrated helps your kidneys to filter toxins and waste, so they can retain essential nutrients and electrolytes. A lack of water can also lead to hard or lumpy stools and stop food from moving through your body properly, causing you to feel bloated and uncomfortable. 

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

5. Swap in sourdough

Contrary to popular belief, you don't need to part ways with carbs such as bread in order to achieve your health goals. It's more about making a simple swap to get all the best nutrients for your body.

“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 may prevent you from reaching for a sugary snack a couple of hours later. 

6. Eat more mindfully

Just like mindful drinking, the concept of mindful eating involves being fully engaged with what we are consuming. “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. 

7. 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. So while you may be eating a nutritious chicken salad, packed with lean protein and your five-a-day, 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 drinks for water instead. “These small changes will make a big difference over time,” she adds.

8. Get moving

Moving enough is key to helping you burn off more calories than you consume. “The combination of activity and consuming a healthy, balanced diet is the best way to support healthy, sustainable weight loss,” says Hope.

But getting active shouldn't feel like punishment. “It’s about finding an activity that works for you," notes Hope. Whether that's taking a spin class, walking with a friend, or simply trying out some at-home workouts. It is recommended you do at least 150 minutes of moderate-intensity activity spread out over the week. Including some strength training is vital as well, as it can prevent you from losing muscle when you lose weight. 

9. Make SMART goals

Planning for long-term weight will certainly be the most successful way to see changes, explains nutrition coach James. And to ensure that you're making the most sustainable goals, you may want to consider implementing some SMART goals. 

"These are specific, measurable, attainable, relevant and time specific," he says. "A good SMART goal will adapt over time to suit your current needs, but you may want to start with something like losing 2lbs in a week, and do so through cutting back calories slightly and increasing your exercise regime.

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Want to lose weight in a healthy, sustainable way? Use this meal plan as a guide

Planning out your meals can ensure you get all the right nutrients and also discourage you from being tempted to pick up a last-minute ready meal on your way home. 

Our nutritionist Jenna Hope has come up with a meal plan to give you a bit of culinary inspiration. "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.” 

If you're unsure or have any specific dietary requirements, seek advice from your doctor.

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

What avoid when you're trying to lose weight

Weight loss is certainly something that everyone who has wanted to do it, or has done it, will have an opinion on—but it's also hugely personal and health, wellness and body weight goals will look different for every person.

When taking on any weight loss or general health plan, Jenna Hope has a few suggestions. 

  • Cutting out foods—it can lead you to desire them more and cause you to overeat. Instead, enjoy a small number of your favorite foods each week.
  • Listening to everyone's opinion—there are many strategies for weight loss and different things work for different people. Once you've made up your mind about how you want to lose weight, ignore everyone else's suggestions, since you may become confused and try to do too much at once.
  • Over-exercising—like everything, there can be too much of a good thing. Over-exercising can significantly increase your appetite, which can make it harder to lose weight. Plus, you risk forming a poor relationship with fitness, which could impact your mental wellbeing.
  • Skipping meals—it can contribute to blood sugar crashes. When blood sugar levels fall, you're much more likely to overeat later in the day and crave sweeter foods at night.  

Natalia Lubomirski is a health journalist with 14 years experience in the publishing industry. She has worked for a number of well-known magazines and websites including Marie Claire, marieclaire.co.uk, woman&home, Top Sante, Boots and The Telegraph. 


She likes to think she practices what she preaches when it comes to health and fitness. She loves the great outdoors and you’ll often find her up a mountain somewhere. She’s climbed eight major mountain ranges across four continents and hit the summit of Half Dome (in Yosemite) during her honeymoon.