The ultimate diet to lose weight fast

Weight loss isn’t the cure-all to every health problem, but there are ways to lose weight safely if your doctor recommends it.

Long-term weight management requires gradual weight loss of a pound or two a week. However, many diet plans intended to help you shed pounds leave you hungry or unsatisfied, or they eliminate major food groups and are not sustainable. 

How to start losing weight?

A healthier diet might be difficult for you for these reasons mentioned earlier. Different eating styles and tips may work better for you than for someone else, as everyone has unique needs.

There are some general principles to follow when trying to lose weight, regardless of whether you follow a low-carb diet or a diet focused on whole foods. Depending on your health status, lifestyle and weight management requirements, here are some diets to try:

Intermittent fasting

There are several different intermittent fasting methods. The most popular ones include [1]:

  • 16:8 method
  • 5:2 diet
  • Warrior diet
  • Eat Stop Eat
  • Alternate-day fasting (ADF)

The best method depends on the individual, but all methods can be effective. Here’s a list of the benefits and drawbacks of each method to let you decide which one’s best for you.

Photograph: Marcin Malicki/Shutterstock

The 16/8 method: a popular fasting plan to lose weight. A set 8-hour window per day is set for food and calorie-containing beverages consumption. 

Here, you must abstain from food for 16 hours. With its time-restricted feeding model (TRF), the 16/8 diet is more flexible than other diets.

Calorie consumption can take place during any 8-hour period. Others refrain from eating late and stick to a schedule of 9 am to 5 pm, skipping breakfast and eating from noon to 8 pm.

Keeping your eating hours limited may help you lose weight and lower your blood pressure. To maximise the health benefits of this diet, make sure you eat a balanced diet that includes fruits, healthy fats, protein, vegetables and whole grains.

The 5:2 method: 

A simple intermittent fasting plan. Five days per week, you usually eat and aren’t supposed to follow any calorie restriction. On the other two days, you consume only one-fourth of your daily calorie needs.

Someone who consumes 2,000 calories per day would have to reduce their calorie intake to 500 calories per day, two days per week, for example. In a 2018 study, the 5:2 diet was equally as effective for weight loss as daily calorie restriction [2].

On the other hand, eating “normally” on full-calorie days does not entitle you to eat anything you like. Even if you limit yourself to just 500 calories a day, it’s still not easy. 

In addition, eating too few calories may make you feel sick or faint. Although the 5:2 diet can be effective, it is not suitable for everyone. Find out if the 5:2 diet is right for you by talking to your doctor.

Eat Stop Eat:

a method of intermittent fasting popularised by Brad Pilon, author of “Eat Stop Eat.” In this method, you identify one or two non-consecutive days per week in which you do not eat, fasting for 24 hours.

You can eat freely the rest of the week, but it is recommended that you consume a well-rounded diet and avoid overindulging. Losing weight can be achieved by consuming fewer calories during a weekly 24-hour fast.

If you fast for 24 hours, your body will utilise fat as an energy source instead of glucose [3]. While avoiding food for 24 hours requires a lot of willpower, it can also lead to overeating and bingeing. Additionally, it may lead to disordered eating habits.

Several studies are needed to determine the potential health benefits and weight loss properties of the Eat Stop Eat diet. Consult your doctor before attempting Eat Stop Eat to see if it can help you lose weight.

Alternate-day fasting: 

An intermittent fasting plan that’s easy to remember. Every other day, you fast, but on the days you are not fasting, you can eat anything you want.

There are versions of this diet that incorporate a “modified” fasting strategy that involves consuming around 500 calories on fasting days. However, other variants eliminate calories on fasting days.

There are proven weight loss benefits associated with alternate-day fasting. A randomised trial examining alternate-day fasting versus daily caloric restriction in obese adults found both methods to be equally effective [3].

Another study found that over the course of four weeks, participants consumed 35 per cent fewer calories and lost a total of 7.7 pounds (3.5 kg) after rotating between 36 hours of fasting and 12 hours of unlimited eating. If you want to maximise weight loss, adding an exercise regime can be helpful.

Combining alternate-day fasting with endurance exercise may double weight loss compared with simply fasting [4]. Fasting every other day can be extreme, especially if you have never done it before. It is also possible to overeat on non-fasting days.

Start with a modified fasting plan if you’re new to intermittent fasting. No matter which fasting plan you choose, it’s important to maintain a nutritious diet that includes low-calorie vegetables and high-protein foods.

The Warrior diet:

Modelled on the eating habits of ancient warriors, created by Ori Hofmekler in 2001. Although the Warrior Diet is more extreme than the 16:8 method, it is less strict compared with Eat Fast Eat.

At night, you eat as much as you want during a 4-hour window after eating very little during the day. During the 20-hour fasting period, Warrior Dieters consume small amounts of dairy products, hard-boiled eggs, vegetables and raw fruits, as well as non-calorie fluids.

For four hours after this 20-hour fast, people can eat whatever they want, although healthy, organic and unprocessed foods are highly recommended. Despite the lack of research on the Warrior Diet specifically, time-restricted feeding cycles can lead to weight loss [5].

Paleo fasting

When you fast, your cells switch from burning glucose to fat as their main energy source. Some evidence indicates that it takes 18 hours for the full effect to occur after food consumption has stopped [6]. 

In order to function efficiently, our bodies switch between using fat or glucose as their primary fuel source. Before even attempting IF, your diet should be something similar to Paleo-ish or shouldn’t be the same as a typical American diet. The body won’t be able to adapt to using fat as the primary fuel source if it is used to running on processed carbohydrates and sugar all day long. 

The ketogenic diet consists of a low-carb and high-fat diet that drastically reduces carbohydrate intake and replaces it with fat [1].

Implementing paleo and IF together: 

If you’re ready to try the 16:8 IF – As stated earlier, you’re already mainly eating Paleo, sleeping well and not currently in a high-stress situation.

For a week or two, gradually ease into IF instead of going from zero to 60 in one day:

  • Firstly, lower your carb intake to prevent hunger-causing insulin spikes and dips.
  • Stop snacking between meals and especially after dinner.
  • Afterwards, move dinner and/or breakfast earlier. Stretch the time in 30-minute intervals until you’re fasting for 16 hours between dinner and breakfast.

Expect some hunger during the transition. A new eating pattern takes time for your body to adjust to since it gets used to eating at regular times. 

Feel free to drink non-caloric beverages like tea and water in between meals. If you’re struggling a bit more, you can try a little bit of bone broth for a few days to help tide you over during a fast. 

Be careful with black coffee. Although calorie-free, it can spike cortisol levels and cause more hunger [6].

Once your feeding window fits within eight hours, two larger meals work better than three regular-sized meals. It’s not a one-size-fits-all approach; you’ll have to tweak your meals to see what works best for you personally.

Keto Diet

Ketogenic diets come in several forms, including:

  • Standard ketogenic diet (SKD): low carb, moderate protein, high fat. It usually contains 70 per cent fat, 20 per cent protein and only 10 per cent carbs [7].
  • Cyclical ketogenic diet (CKD): involves periods of higher carb refeeds, like 5 ketogenic days then by 2 high carb days.
  • Targeted ketogenic diet (TKD): allows you to include carbs around workouts.
  • High protein ketogenic diet: similar to a standard ketogenic diet, but contains more protein. The ratio is often 60 per cent fat, 35 per cent protein and 5 per cent carbs.

The standard and high-protein ketogenic diets, however, have been extensively studied. A cyclical or targeted ketogenic diet is more advanced and is primarily used by atheles or bodybuilders.

What is ketosis: 

It is a metabolic state in which fat is utilised as fuel in place of carbs. It happens when you drastically reduce your consumption of carbs, decreasing your body’s glucose (sugar) supply, which is the principal energy source for cells.

Ketosis is most effectively achieved through a ketogenic diet. In general, this involves consuming fewer than 20 grams of carbohydrates a day and consuming fats like eggs, fish, healthy oils, meat and nuts [8].

You should also moderate your protein intake. The reason for this is that protein can be converted into glucose if ingested in high amounts, may slow the ketosis process [9].

You may also be able to enter ketosis more quickly by practising intermittent fasting. Losing weight and reducing risk factors for disease can be achieved with the ketogenic diet [101112]

There is evidence that the ketogenic diet is just as effective as a low-fat diet in reducing body weight [13]. It is so filling that you can shed pounds without even counting calories or tracking your food intake [14]. 

A review of 13 studies found that a low-fat diet was slightly more effective than a very low-carb diet for long-term weight loss. Keto diet followers lost an average of 2 pounds (0.9 kg) compared with low-fat diet followers.

Longevity diet

Dotted around the world, Blue Zones house the highest amount of centenarians than anywhere else in the world.

Here are some guidelines for adults who want to follow the longevity diet [15]:

  • Fish should be limited to two or three meals per week, and most meals should be vegan. Pay attention to the freshness of the fish, choosing those with low mercury levels (salmon, anchovies, sardines, cod, sea bream, trout, clams, shrimp).
  • Keep your protein intake low (0.31 to 0.36 grams per pound of body weight if you are under 65). For someone weighing 130 pounds, that would be 40 to 47 grams of protein a day, and for someone weighing 200 to 220 pounds, it would be 60 to 70 grams per day. If you are over 65, you should consume more protein and consume fish, eggs, white meat and goat and sheep products to preserve your muscle mass. Your primary source of protein should be beans, chickpeas, green peas and other legumes.
  • Make sure you minimise saturated fats from animal and vegetable sources (meat, cheese) and sugar and maximise good fats and complex carbohydrates. Eat whole grains and vegetables (tomatoes, broccoli, carrots, legumes and so on.) with generous amounts of olive oil (3 tablespoons a day) and nuts (1 ounce a day).
  • Take a multivitamin buffer every three days along with a diet high in vitamins and minerals.
  • You should choose ingredients from this book that your ancestors would have eaten.
  • Consider your age, weight and abdominal circumference when deciding how many meals to eat each day. Consume two meals daily if you are overweight or tend to gain weight rapidly: breakfast, lunch, or dinner, plus two low-calorie snacks (less than 100 calories each). Eating three meals a day and a low-sugar snack (less than 3 to 5 grams) with fewer than 100 calories is advisable for people who are already at average weight, tend to lose weight quickly, or are over 65 and of average weight.
  • Confine all eating to within twelve hours. For instance, start after 8 am and end before 8 pm. You shouldn’t eat anything within three to four hours of going to bed.

Low-carb diet

The number of carbs permitted each day varies between the different low-carb diets. Sugar, starches and refined grains are usually limited in low-carb diets. Low-carb diets include Keto, Atkins, South Beach, Paleo and Dukan.

A low-carb diet should include a variety of minimally processed, low-carb foods, including protein sources, non-starchy vegetables and high-fat dairy products [16]. Low-carb diet foods include:

  • Meat: beef, chicken, lamb and pork, 
  • Fish: haddock, salmon, trout and tuna
  • Eggs: whole eggs, egg yolks and egg whites
  • Non-starchy vegetables: asparagus, broccoli, cauliflower, carrots, tomatoes and spinach
  • Lower carb fruits: blackberries, blueberries, oranges, raspberries and strawberries
  • Nuts and seeds: almonds, chia seeds, pistachios, sunflower seeds and walnuts
  • High-fat dairy: butter, cheese, Greek yoghurt and heavy cream, 
  • Fats and oils: avocados, avocado oil, coconut oil, lard and olive oil

Limit your consumption of high-calorie foods like cheese and nuts if you’re trying to achieve or maintain a moderate weight. If you’re not following a very low-carb or keto diet, you may want to include small amounts of the following foods:

  • Starchy vegetables: corn, potatoes, sweet potatoes, yams and peas
  • Higher-carb fruits: bananas, mango, pineapples and many others
  • Whole grains: brown rice, quinoa and oats
  • Legumes: black beans, chickpeas, lentils and pinto beans
  • Higher-carb dairy: milk and full-fat yoghurt

In adition, moderate consumption of the following is okay:

  • dark chocolate with at least 70 per cent of cocoa
  • dry wines with no extra carbs or sugar

In moderation, dark chocolate may provide health benefits due to its high antioxidant content. You should be aware, however, that eating or drinking too much dark chocolate and alcohol may hinder weight management [17].

A note on calorie counting

Calorie counting may be helpful for some people, but it may not be suitable for everybody. Consider seeking support if you are preoccupied with food or weight, feel guilt about your food choices, or engage in restrictive diets often. 

Eating disorders and disordered relationships with food can cause these behaviors. A registered dietitian can help you if you’re struggling.

There are organisations like the National Eating Disorders Association where you can chat, call, text anonymously or explore their free and low-cost resources.

[1] https://www.healthline.com/nutrition/6-ways-to-do-intermittent-fasting/
[2] https://pubmed.ncbi.nlm.nih.gov/30646030/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042570/
[4] https://pubmed.ncbi.nlm.nih.gov/23408502/
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836017/
[6] https://www.ncbi.nlm.nih.gov/pubmed/21346100
[7] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6251269/
[8] https://www.ncbi.nlm.nih.gov/books/NBK499830/
[9] https://www.ncbi.nlm.nih.gov/books/NBK541119/
[10] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3945587/
[11] https://pubmed.ncbi.nlm.nih.gov/30289048/
[12] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836058/
[13] https://pubmed.ncbi.nlm.nih.gov/23651522/
[14] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4313585/
[15] https://www.valterlongo.com/daily-longevity-diet-for-adults/
[16] https://www.healthline.com/nutrition/44-healthy-low-carb-foods
[17] https://www.frontiersin.org/articles/10.3389/fimmu.2017.00677/full

Photograph: New Africa/Shutterstock
The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.