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Your Guide to Dieting: 4 Popular Diets, Research, Benefits and Considerations

A complete overview of the most popular contemporary diets; from keto to intermittent fasting and plant-based diets - how they work, their unique benefits, and how you could implement them in your nutrition.

There are countless ways to feed your body, which means some diets will bring quicker and better results than others depending on your goals. When choosing a diet, not only are your goals important but also your relationship with food and the amount of time you have to commit to your nutrition.

Before you dive into a diet remember that food is incredibly personal and emotional. If you’re after lasting change, choose an individualised diet you can sustainably stick to long term, as consistency over time will bring the biggest results.

No matter which diet you follow, generally you should try to stick to healthy eating habits if you want to improve your general health.

Disclaimer: All content within this article is provided for general information only and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. Always consult a dietitian before making big changes to your diet.

In this article:

What is a dietVegan and Vegetarian
Intermittent FastingKetogenic Diet
Mediterranean Diet

What is a diet?

In nutrition, a diet is the food and drink regularly consumed by a person. Diets are most often associated with regiments of eating to achieve weight loss or for medical treatment, but in reality our diet encompasses our habitual nourishment.

A key aspect about diets and nutrition is the concept of calorie balance. Calorie balance is the ratio between calories taken in and calories expended in by one individual at any given time. This is the most important factor when it comes to changing your weight. What you actually need on a daily basis will be individual to you based on your age, lifestyle and fitness habits.

There are three states of calorie balance and you can only be in one at any one time. A negative calorie balance will always result in weight loss, but because you’re not providing your body with the energy it needs, being in a (big) negative calorie balance for a long time might lead to fatigue and slow recovery.

This is part of the reason why sustainable approaches are recommended, where you might not see or feel huge change within the first month, but if you’re successful your weight, habits and relationship with food won’t fluctuate throughout the years.

healthy dietsSource: Jamie Street on Unsplash

Know it is not the end of the world if you digress from your diet every now and then, just make sure you allow yourself enough freedom so you don’t feel like overcompensating when you get back on track.

Many diets are so restrictive that they can’t be sustained long-term. We recommend having a deep think about what your goals really are before committing to one. Always consult a medical professional before making any radical changes to your diet, especially if you suffer from underlying health conditions.

It can take a very long time to fully adopt a new diet and learn how to shop, cook and enjoy what you eat, but we hope our complete guide to modern diets makes the process easier.

Vegan and Vegetarian

  • Overview: plant-based eating
  • Good for: ethical consuming, sports performance, general health
vegan and vegetarian summer rollsSource: Ella Olsson on Unsplash

Vegan and vegetarian diets are eating forms where only plant-based foods are consumed. The main difference between vegans and vegetarians is that the former don’t consume any animal products, while the latter includes by-products of animals like dairy and eggs.

A vegan diet is one in which no animal foods or animal by-products are consumed, this includes collagen and gelatine. Many vegans also follow this approach in daily life, steering away from products such as leather or anything animal tested. 

Many people choose to follow either of these diets for ethical reasons, because of environmental concerns or to improve their health.

Following a vegan or vegetarian diet is generally considered a healthy way of eating and has proven to improve heart health and reduce the risk of type 2 diabetes. However, this is only true if the diet doesn’t heavily consist of vegan or vegetarian processed foods.

How it works

A vegan diet includes fruits, vegetables, nuts, roots, seeds and grains, but steers away from products such as meat, seafood and dairy.

A vegetarian diet is similar, but includes dairy products such as milk, yogurt and cheeses, as well as animal products such as eggs and honey.

There are no timing or portion concerns when it comes to vegan and vegetarian diets, the only restriction comes from what you can eat. You’re likely to consume more fruits and vegetables when you transition into a plant-based diet, and you might reduce your intake of process foods.

Vegan and vegetarian diets are rich in whole foods, such as fruits, vegetables, seeds, legumes, beans and whole grains. This means they contain plenty of valuable micronutrients and there are numerus benefits to adopting these diets.

The key benefits to vegan athletes compared to non-vegan foods and products are the higher intakes of complex carbohydrates, dietary fibre (only present in plants), antioxidant vitamins C and E, folic acid, magnesium, potassium and sodium.

Considerations and what to expect

One of the main concerns with vegan and vegetarian diets is consuming enough protein. Protein deficiency isn’t very common among vegans and vegetarians in the US, and you should be able to meet your protein needs simply by eating a wide array of foods.

“Protein is in everything,” Marco Springmann, senior researcher of environmental sustainability and public health at the University of Oxford, told the BBC. “[…] the vegan diet is higher in fruit, vegetables and legumes and the health benefits from this compensate anything else.”

Generally, vegan diets are balanced in the nutrients they include, so nutrient deficiencies aren’t a big concern. Some studies suggest people following a vegan diet should supplement with vitamin B12. B12 helps prevent nerve damage and is naturally present in foods of animal origin.

However, in many parts of the world, foods such as breakfast cereals or yeast in plant milks are fortified with vitamin B12 with high bioavailability.  

Numerous studies have found that, in most cases, nutritional deficiencies emerge though misapplied dietary behaviour – poor application of a diet – and not through the nutritional adequacy of the diet itself.

Some people might have trouble adopting the diet if they have followed an omnivore eating style all their lives. Strategies such as “add first, subtract later” approach are great ways to get started. This approach simply mean you add more vegan or vegetarian meals to your daily nutrition before getting rid of the foods that are not compliant with the diet.

Food alternatives

There are many vegan and vegetarian friendly protein-rich foods. They include:

  • Seitan
  • Tofu
  • Quinoa
  • Beans
  • Lentils

Read more: Healthy Vegetarian Protein Sources for Athletes

There are also many plant-based meat alternatives you could try. From burgers to sausages, you can find tasty vegan and vegetarian alternatives to your favourite dishes in most big supermarkets.

Dairy alternatives include soy-based yogurt, dairy-free milks such as almond, oat or soy milk, and soy-based cheeses.

Recipe ideas

Removing animal products from your diet can be hard, as you’ll most likely need to reinvent your cooking habits. Investing in a vegan or vegetarian cookbook is always a great first step, or you could try to find recipes online to gain a better understanding of what you could eat.

Personal favourite vegan and vegetarian recipes include:

Intermittent Fasting

  • Overview: eat only at specific times of the day, with prolonged periods of fasting
  • Good for: weight loss, calorie intake management
breakfast toast interrupts fasting period
Most people interrupt their night fast with breakfast.

Intermittent fasting (IF) is a type of diet that doesn’t restrict what you eat, but when you eat.

It involves constraining the times you eat, with regular periods of no food consumption known as fasting.

While the length of these fasting periods varies, the most popular approaches see people on this diet fast for a large part of the day, fast a few days per week, or fast several days each month.

The diet has been studied for its effects on weight loss, however, not much is yet known about the long-term health effects of following IF. A big advantage to this diet is that it doesn’t require you to eliminate entire food groups from your diet, so you can continue to shop, cook and eat what you’re used to, and simply vary when you eat.

How it works

There are many ways to follow intermittent fasting, the most popular include:

  • Time-restricted feeding, where food intake is limited to a specific time period during the day, usually between six and eight hours long.
  • The 16:8 method, in which you fast for 16 hours and have an eight-hour eating window.
  • The 5:2 diet, where you eat normally for five days a week, then reduce your calorie intake to one-quarter of your daily needs for the other two days of the week.
  • The Eat Stop Eat diet, which involves identifying one or two non-consecutive days per week during which you abstain from eating, or fast, for a 24-hour period.

These methods can also include calorie restrictions in addition to time restrictions.

Non-caloric beverages such as water, black coffee or tea are the allowed during the fasting periods.

In most cases, by limiting when you eat, you naturally consume less calories than you otherwise would, thus entering a caloric deficit and losing weight. Whether is through cutting out on snacking or the discomfort of eating two whole meals in one sitting, narrowing down the window of time you allow yourself to eat ultimately tends to lead people to consume fewer calories overall.

Read more: How to Lose Weight with Fasting

The idea behind IF is that people will lose weight by lowering their insulin levels. Excess sugar from the food we consume is stored in our fat cells, to be used as energy in the future. Sugar can only enter these cells with insulin; the hormone is in charge of bringing sugar into the fat cells and keeps it there.

During fasting periods, our insulin levels go down and fat cells release their stored sugar for energy. In theory, if our insulin levels go down far enough and for long enough, we burn off our fat. In reality, the evidence supporting this theory is currently not conclusive.


Benefits of intermittent fasting include:

While IF might be restrictive, it might be easier for some to follow this diet long-term as it doesn’t require you to eliminate whole food groups from your diet or change your food choices entirely.

Other benefits include a relative easy to follow the diet, no calorie counting, no limitations on food types (although a varied and balanced diet is recommended) or calories.

Considerations and what to expect

Many cultures around the world practice fasting for religious or spiritual reasons. The diet became popular in Western cultures around 2013, after a handful of small studies suggested it promoted a wide range of metabolic benefits such as reduction in insulin resistance and improved cholesterol profiles.

General considerations include the possibility of side effects during fasting days and the fact that the diet doesn’t directly encourage nutritious eating.

A thorough study in 2020 found that overweight adults who followed the 16:8 diet over three months gained almost no benefit from it. Additionally, most of the weight they did lose consisted of not body fat but lean mass, which includes muscle.

The researchers speculated that one of the reasons for this might be that fasting lead to people to consume less protein. This could be avoided, as pointed by this study, if people include resistance training in their lifestyle and consume more protein during their eating windows.

snacks and small portions of foodSource: Rachael Gorjestani on Unsplash

Many believe intermittent fasting is a great diet for weight loss as it helps reduce insulin resistance. While this might be the case, research on the topic is still emerging.

Intermittent fasting might be an effective tool to weight loss simply because people subconsciously tend to reduce their caloric intake, while paying more attention to what they eat, when following the diet.

Additionally, the majority of research completed on IF includes only men, and there is evidence that the diet might have different effects based on gender.

Important: while there is evidence that intermittent fasting can be an effective and sustainable way to lose weight and improve your health markers, especially when combined with a healthy diet and lifestyle, people with diabetes, a history of eating disorders, or pregnant women should only attempt the diet under close supervision of a qualified professional.

Intermittent fasting in a nutshell

“Studies in humans, almost across the board, have shown that IF is safe and incredibly effective, but really no more effective than any other diet,” writes Monique Tello, MD, MPH, in Harvard Health.

This is supported by a 2021 review study published in the Annual Review of Nutrition which analysed the cardiometabolic benefits of intermittent fasting.

Recipe ideas

No healthy eating guidelines, cooking methods, or shopping guidelines are provided on most IF plans.

Therefore, it is recommended you stick to varied, primarily unprocessed, and balanced foods.

Keto Diet

  • Overview: extremely low carb diet
  • Good for: weight loss, therapeutic uses
plate of food compliant with the keto dietSource: David B Townsend on Unsplash

The ketogenic diet, also known as the keto diet, is a very low carb diet designed to bring your body into a state called ketosis. In this state, your body uses fats instead of glucose for energy.

The keto diet gained popularity around 2017 and is one of the fastest growing mainstream diets, praised for its effects on rapid weight loss. However, the diet has as many followers as it has opponents, with some nutrition experts worrying that it is too strict to be sustainable and having doubts about its safety.

The diet has been used in the past for medical purposes to treat epilepsy and there’s a fair bit of research backing up its therapeutic purposes.

There are no time restrictions, however, there’s little flexibility in what you eat because carbohydrates are so severely restricted. Non-compliant foods include most fruit, high-fibre vegetables, bread and pasts, wholegrains and rice, and sweet desserts.

How it works

Most ketogenic diet plans recommend having 70% of your calories as fat, 25% as protein, and 5% as carbs. The aim of the diet is to get your body to use fats as its main source of energy, in a state called ketosis.

It can take several days or several weeks to get your body into ketosis.

Keto meals are cantered around fat-rich foods such as fatty fish, meat, nuts, cheeses, low-carb vegetables, and oils.

They can also be vegetarian or vegan, with plant-based fats (such as avocado, nuts, seeds, coconut, flax and olive oil) and proteins (such as tofu, tempeh, seitan, lupini beans, and pea protein). Note that there are fewer plant sources of fat than there are dairy and meat sources of fat, so food variety will be limited.

While there is strong evidence to support the ketogenic diet is effective for weight loss, researchers have contrasting theories regarding the mechanisms through which this diet works. Many believe the result simply comes from reduced caloric intake, probably due to the increased satiety effect of protein and loss in water weight.

Others suggest that it’s the change of energy source which, through a complicated process, can result in increased weight loss. However, there’s no direct evidence to support changes in resting energy expenditure after following the ketogenic diet.

Ultimately, it’s most likely that weight loss seen through following the keto diet is a result of several factors.


There is strong evidence to suggest the ketogenic diet can be beneficial for:

  • Epilepsy: influencing neurotransmitter activity, reducing neural excitability bodies, and through the direct anticonvulsant effect of ketone bodies.
  • Weight reduction: reducing in appetite, increasing lipolysis, and increasing the metabolic cost of energy production.
  • Diabetes: reducing blood insulin level and reversing hepatic insulin resistance.
  • Cardiovascular risk parameters

Additionally, there’s emerging evidence that the diet might be beneficial for people suffering from acne, neurological disease, or cancer.

Considerations and what to expect

The keto diet is often labelled as an “extreme diet” because it is very low in carbohydrates and radically different to what mainstream dietitians recommend (a balanced, healthy, and nutritious diet).

As with any other diet, the main consideration with keto is adequate attention to food quality. Without it, any macronutrient-focused eating pattern can have adverse effects.

You’ll have to be mindful to consume healthy produce throughout to minimise the risks and maximise the benefits of the diet.  

The “keto flu” is a common occurrence with people following the diet, with many reporting fatigue, weakness, headaches, and irritability as their bodies adjust to ketosis. Beyond these initial symptoms, a 2020 study found that a “a well-formulated ketogenic diet does not appear to have major safety concerns for the general population.”

However, it noted that there’s still a lack of high-quality clinical trials that hinders scientific understanding and public health translation.

pan with high fat ingredientsSource: Dana DeVolk on Unsplash

It is common for people to be initially thrilled by the initial weight reduction they experience with the diet, but either get bored or frustrated when they plateau and increase their carbohydrate intake, reversing its effects. In many instances, the weight that is lost is regained within a short period of time when people go off the diet.

Ultimately, there’s questions about the sustainability of the diet. It can be hard for many people to completely eliminate foods they love from their diet if they don’t have a medical condition.

There are also reports of micronutrient deficiency and cardiovascular safety, and the long-term (greater than one year) effects of following this diet are still generally unexplored. The general consensus is that more research is needed before the ketogenic diet is widely recommended.

Keto recipes

Severely reducing your intake of carbs can be hard and most people following keto are likely to have to reinvent their shopping and cooking habits. Here are a few ideas of what you could eat on a keto diet.


  • Overview: variety of nutrient-dense food choices and flavourful meals
  • Good for: longevity, healthy eating
Mediterranean food plateSource: Jez Timms on Unsplash

Based on traditional foods eaten by people living around the Mediterranean Sea, the Mediterranean diet is classed as one of the healthiest in the world. The food in this eating regime is full of nutrient-rich options such as fruits, vegetables, whole grains, fish and olive oil.

It was popularised because Mediterranean people are known for their longevity, relative low rates of heart disease, and staying healthy even in the later stages of life.

It is a great option for people looking for a sustainable approach to their nutrition, something they can follow long-term, as it is not a diet plan in the conventional sense, rather an eating (and lifestyle) habit. The Mediterranean diet pyramid includes being physically active and enjoying time with others at its base.

It’s not necessarily the diet that works, but the fact that it’s full of varied, healthy, unprocessed foods, physical activity, and social interaction.

How it works

The Mediterranean diet is characterised by a high intake of olive oil, fruits, nuts, vegetables, and cereals, a moderate intake of fish and poultry, and a low consumption of red meats, diary products, and sweets.

Red wine can also be consumed with meals in moderation.

The diet provides vitamins, minerals, fibre, and a healthy combination of carbohydrates, fats and protein. It’s also been praised for being mostly non-restrictive, which makes adherence a lot easier for many, and including lifestyle factors in its recommendations.

In a nutshell, this diet is abundant in minimally processed plant-based foods, rich in monounsaturated fat from olive oil, but lower in saturated fat, meats, and dairy products. It is one of the top diets recommended for long-term health.


Research suggests that the Mediterranean diet may help:

A 2009 systematic review found this diet as the most likely one to provide protection against coronary heart disease. Additionally, a 2018 study found that following a Mediterranean diet was associated with reduced risk of depressive symptoms or clinical depression.

Compared to other diets, it’s very easy to get started with the Mediterranean way of eating. You might need to come up with new recipes, but all recommended foods should be readily available in your local supermarket.

No major food groups are cut out with this diet and variety in meals is encouraged, so it is one that can be followed safely by most of the population.

Considerations and what to expect

While the Mediterranean diet is generally praised, it does not offer specific guidelines such as calorie counts or food portion sizes for those who like them, and so additional guidance might be needed.

It is not the best diet for people looking to achieve weight loss, however, research has found that people do not gain weight when following a Mediterranean diet.

People in Western countries might also benefit from checking they are meeting they Vitamin D needs. While this might not be of great concern for people in the Mediterranean area, requirements for Vitamin D might not easily be met by adopting this diet outside of the sunny region.

Another concern is that, because many recommended foods in this diet are not local to Western countries and the healthy options are usually expensive, following the diet can be a little costly.

mediterranean diet dishesSource: Mor Shani on Unsplash

It might be hard to cut out on red meat and added sugar consumption, but if you start in small steps – eliminating them from your meals once a week for example – this process can be easier.

To fully reap the health benefits of the Mediterranean diet, you’ll have to include physical activity (this doesn’t necessarily have to be sport, it could simply mean moving around throughout the day) and positive social interaction in your lifestyle too.

Mediterranean diet recipes

Because the Mediterranean diet is more of an eating pattern, here are a handful of recipes you could try out:

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