Diets that work fast: fastest diet plans for quick results

Want to know how to lose weight fast? You could lose seven pounds in seven days on one of these easy quick fix diets that work!

A bowl of fruit and veg in a heart shape, surrounded by exercise equipment
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When you're trying to lose weight, it's easy to think diets that work fast are the way forward. Quick and easy, many promise maximum weight loss in minimum time. 

But the more extreme weight loss methods often promote unhealthy weight loss ideas and can end up causing more problems than creating solutions in the long run. As advice from the NHS says, "If you're trying to lose weight, the safe weekly rate of weight loss is between 0.5kg and 1kg. That's between around 1lb and 2lb a week. Lose weight faster than this and you're at risk of health problems that include malnutrition and gallstones, as well as feeling tired and unwell."

Experts from the NHS to dieticians and personal trainers will confirm that losing weight consistently is better for long term weight loss than a sudden drop, there are some ways to lose pounds quickly that are healthy. So whether it's lockdown weight gain you're trying to shed or just looking to transform your diet, these are the diets that actually work.

Which are the diets that work fast?

When trying to lose weight, whatever the diet you choose, establishing a calorie deficit is a "great place to start". Constantinos Yiallouros, the head of fitness at Anytime Fitness UK, says, "Without expending more calories than you take in, you’re unlikely to lose weight and achieve the results that you want.

"There are simple tools online for you to calculate the number of calories that your body needs to maintain your weight. From then, you need to set yourself an achievable deficit which you can attain from your food consumption and your physical activity. There’s no one size fits all approach but in general, the rule of thumb is that by having a daily deficit of 500 calories, it should result in one pound of weight loss per week."

Diets that work fast

1. High protein diet plan

High protein diets work fast - and more easily than others. Studies from The American Journal of Clinical Nutrition show that a higher intake of protein increases the level of fullness you feel. This is because protein works to increase the hormones GLP-1, peptide YY and cholecystokinin and decrease the ghrelin hormone, which causes hunger. It also works to increase your metabolic rate while sleeping.

A collage of pulses and legumes that are high in protein

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Foods that are high in protein are also easily-accessible, with plenty of high protein breakfast ideas out there. This diet doesn't require a special plan either, other than the standard calorie deficit if you're looking for optimum weight loss. Foods with a particularly high protein count include:

  • Eggs (6g of protein per egg)
  • Nuts, especially almonds (6g of protein per 28g)
  • Chicken (53g of protein per chicken breast)
  • Oats (11g of protein per 128g)
  • Lean beef (25g of protein per 85g)
  • Tuna (27g of protein per 142g)
  • Lentils (18g of protein per 198g)
  • Greek yogurt (17g of protein per 170g)

There are many diets that revolve around this idea with The Dukan Diet being one of the most popular high-protein plans out there.

Find out more about the high protein diet

2. Detox diet plan

'Detoxing' is a buzz word in the diet and wellness industry. While many people immediately associate detoxing with green juices, kale smoothies and a lack of 'real' food, it doesn't have to be that way. The body naturally takes itself through a detox with processes in the liver and kidneys, but the addition of more macronutrients, vitamins and minerals in your diet will help the journey along. More fruits and vegetables have also been linked to better skin, an improvement in hair growth and more energy day-to-day - as well as weight loss.

Some of the best foods to eat on a detox include those that include high amounts of protein, B vitamins, vitamin E and C, magnesium, selenium and zinc. These include affordable, accessible and versatile foods such as potatoes, wholemeal toast, yogurt, eggs, green and fibrous vegetables, lentils and chickpeas.

As all these foods are also low in calories, you're more likely to be able to get into your calorie deficit as well and stay full in the meantime. As the foods are lower in calories, you can have more of them without exceeding your target for the day.

Find out more about the detox diet plan 

3. The 5:2 diet

Just one of the ways to get into intermittent fasting, the 5:2 diet plan is one of the most popular diets that work fast out there. It involves fasting, which is eating a restricted number of calories for two days of the week and your maintenance calorie level for the other five. While some people have said that your calorie target on fasting days should be around the 600 mark, founder of the diet Dr Michael Mosely has also said that 800 calories on fast days is a good number to aim for to achieve results.

An alarm clock on a plate

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This comes largely from research on similar types of short-term, low-calorie diets of around 450 to 800 calories per day. One study from 2017 found that both rapid weight loss and long-term weight loss plans "caused reduction in waist circumference, hip circumference, total body water, body fat mass, lean body mass, and resting metabolic rate (RMR)". They did find, however, that those who lost weight slowly over time retained more muscle mass than those who did it quicker.

Intermittent fasting may be difficult when you get going and the 5:2 diet should only be attempted for a limited amount of time before going into your maintenance phase. But, it's a successful way to drop pounds quickly.

Find out more about the 5:2 diet plan

4. The 16:8 diet plan

A similar plan to the 5:2 but with a different time scale is the 16:8 diet plan, which uses similar theories of calorie restriction to create a diet that works to help weight loss quickly.

The 16:8 diet plan stems from the 8 Hour Diet book by author David Zinczenko and editor-in-chief of Men's Health, Peter Moore. They suggest that a longer fasting time between eating gives the body the time it needs to process the food and burn away any extra fat. Also called the 8 Hour Diet, this type of intermittent fasting breaks the day up into two parts - a 16 hour period and an 8 hour period. For the larger portion of the day, you eat and drink nothing but water, coffee and other unsweetened drinks. Then for eight hours, you eat all your meals and snacks.

While the 16 hour period may seem like ages, this is stretched over your regular sleeping time so you're only fasting for about eight hours in actuality.

A 2014 review into 16:8 fasting shows that it's a good alternative to traditional methods of getting into a calorie deficit. It also helps to reduce the risk of type 2 diabetes and aids weight loss in people who are overweight or obese.

Another study from 2018 found that this 8-hour eating window could also help to reduce blood pressure in adults who are obese.

Find out more about the 16:8 diet plan

5. Palaeolithic diet plan

The Paleo diet plan is all about going back to the basics and has long been cited as one of the diets that work fast. This plan involves eating mainly whole foods, vegetables, fruit, lean meats, nuts and seeds, similar to how hunter-gatherers would have eaten all those millennia ago. Much like the detox, the Paleo diet also restricts particular foods, including processed items, grains, sugar, and dairy in some circumstances.

One study published in the American Journal of Clinical Nutrition found that a Palaeolithic diet "resulted in greater short-term improvements in metabolic syndrome components than did guideline-based control diets." This means that the diet was found to be better than standard portion and calorie-controlled diets at improving our metabolic rate, which helps us to burn calories outside of exercise.

Sliced steak on a bed of salad

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Another set of research from 2016 on people with type two diabetes found that the diet improved fat mass and metabolic balance, improving insulin sensitivity, glycemic control, and leptin.

There's also multiple studies that suggest the Paleo diet could be more effective for weight loss than similar ones, such as the Mediterranean diet or low-fat diets. One study from 2013 which looked at the difference between the Paleo diet and the diabetes diet suggests this might be because the Paleo diet is orientated around high-protein foods. These are more filling and help you feel satiated for longer.

Find out more about the Palaeolithic diet plan

6. Low-carb diets

It's not recommended to cut carbohydrates completely from your diet. As Constantinos says, "you still need to be consuming the right foods to achieve your [calorie] deficit. Having a healthy balance of fats, proteins and carbohydrates is the essential backbone of your diet." 

However, there are plenty of low-carb diets that have hit the headlines over the years for being effective diets that work fast to help people lose weight. Our bodies break down carbohydrates and fat into sugar, which then gives us lots of energy. These diets are based around the idea that if we don't eat carbohydrates then our bodies will used fat which has been stored for energy instead, allowing us to lose weight quickly.

The most popular ones include the Atkins diet and the ketogenic diet. However, these are two of the more drastic diets as they cut down carbohydrate levels to less than 10% of total calories. According to the Dietary Guidelines for Americans, this should normally be a minimum of 45%. So while these diets may have their benefits, be sure to consult a health professional beforehand if you're thinking of taking one on.

For a less restrictive version of the ketogenic diet, many prefer the Lazy Keto Diet which is significantly less restrictive and you don't have to track all your macronutrients.

Find out more about low carbohydrate diets 

7. The Mediterranean diet

People living in Mediterranean countries, such as Italy and Greece, have traditionally followed a diet that's mainly composed of:

  • Fruits
  • Vegetables
  • Whole grains
  • Bread
  • Legumes
  • Nuts and seeds
  • Potatoes
  • Red wine
  • Fish and poultry
  • Dairy and eggs

While all these components are high in macronutrients, including carbohydrates and protein, the main fat in the Mediterranean diet is extra virgin olive oil. Red meat also only plays a very minor role in the diet.

A skillet of shakshuka

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There are several studies which show that the rates of heart disease in these countries seems to be significantly lower than those living in the United States. Meanwhile, the Fast 800 Diet - which follows a Mediterranean-style diet has been praised for reducing blood sugar levels and reversing type 2 diabetes.

Further research published in The Journal of the American Medical Association in 2004 also shows, however, that the Mediterranean diet is an effective method of weight loss as well. In this particular study, almost 200 people with metabolic syndrome followed either a low fat or a Mediterranean diet for two and a half years. At the end of the study, 44% of patients who had followed the Mediterranean diet still had the condition - compared to a significantly higher 86% of the patients on the other diet.

The same group on the Mediterranean diet experienced an overall decrease in body weight as well, suggesting that over even just a short period of time, this is an effective weight loss method. This was by 4kg in the Mediterranean group and just 1.2kg in the low fat diet group.

In a similar study from 2008 involved 322 people with obesity. Participants followed either a calorie-restricted low fat diet, a calorie-restricted Mediterranean diet or a unrestricted low carbohydrate diet. The group who followed the Mediterranean diet showed similar results to the earlier study with an average weight loss of 4.4kg over one year. This is compared to the low fat group who lost 2.9kg and the unrestricted, low carbohydrate group who lost 4.7kg over the same time period.

Find out more about the Mediterranean diet

How important is exercise for weight loss?

Exercise and diet are equally important as each other for weight loss, says Constantinos at Anytime Fitness, as they "work together in tandem". 

He says, "I would say that initially, your diet is the most important thing to focus on and it isn’t unheard of that a personal trainer would give a client two weeks or so to focus on getting their nutrition right before starting their physical activity programme.

"By dieting alone, consistent weight loss can be more difficult due to your body quickly adapting to your lower calorie intake and becoming more efficient in processing food. While you may see an initial drop on the scales, this will likely tail off as to keep up the same rate of weight loss, you will need to keep cutting even more calories which is unlikely to be sustainable.

"There are several scientific studies that show people lose more body weight by combining diet and exercise. Furthermore, not only do you lose more weight, almost all of it will go hand in hand with a reduction in body fat. If you’re losing weight by dieting alone, you are likely to be losing muscle mass too which can further reduce your metabolic rate." 

And Constantinos reminds us that the quicker you lose weight, the less sustainable it will be. So while diets that work fast might offer results quickly, for long-term results you have to go for long-term weight loss plans. He says, "Rapid weight changes are usually a result of something extreme taking place, such as not eating enough or overtraining.

"By consistently sticking with your new healthy diet and exercise regime, the results will come and your health will improve over time."

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Grace Walsh
Features Writer

Grace Walsh is a health and wellbeing writer, working across the subjects of family, relationships, and LGBT topics, as well as sleep and mental health. A digital journalist with over six years  experience as a writer and editor for UK publications, Grace is currently Health Editor for and has also worked with Cosmopolitan, Red, The i Paper, GoodtoKnow, and more. After graduating from the University of Warwick, she started her career writing about the complexities of sex and relationships, before combining personal hobbies with professional and writing about fitness.