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Nutrition today: What diets are trending and what does science say about them?

Nutrition today: What diets are trending and what does science say about them?

Published: 15 June, 2023 - Updated: 26 October, 2023 | 14'

World Nutrition Day, celebrated every May 28th, reminds us of the importance of following healthy habits in our diet. Although more and more people are aware of maintaining a healthy and balanced diet, today's society is filled with information, myths, and fad diets that can make it difficult to choose the most suitable option for our health.

Therefore, in this article, we have the collaboration of Doctor Yaiza Acosta, a nutritionist and sports doctor, and María Mercedes Sánchez, responsible for the Scientific Information area of MARNYS, to delve into the most popular diets today and analyze what science says about them.

What is nutrition and why is it important for your health and well-being?

We can define nutrition as the set of involuntary processes that our body carries out to transform the food we eat into the nutrients it needs to function properly.

These nutrients obtained from food are what provide us with the energy and essential elements for the growth, repair, and maintenance of our tissues and organs. Therefore, a balanced diet is essential to maintain good health.

What are the benefits of good nutrition for physical and mental well-being?

As explained by Dr. Yaiza Acosta, a nutritionist and sports doctor: "Good nutrition is essential to maintain good overall health. Over the years, it has been discovered that our gut microbiota influences our physical and mental health, so a balanced diet will provide us with the necessary nutrients for the proper functioning of our body. Nutrition also affects mood, cognitive performance, and sleep".

What factors affect people's nutrition?

Nutrition is directly influenced by the set of food and drinks we consume, that is, the diet. As analyzed by the person in charge of the Scientific Information area of MARNYS, María Mercedes Sánchez, various factors influence, "from access to food, to culture, religion and dietary traditions, the socio-economic and educational level of the individual, to lifestyles and physical activity".

How has nutrition evolved and what challenges does it present for public health?

The World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) define a healthy diet as one that promotes individuals' growth and development and prevents malnutrition.

Based on this definition, all nutrition policies in the world rely on this foundation. Therefore, the Commission called EAT Lancet, made up of experts in different fields of human health, agriculture, policy, science, and environmental sustainability, has highlighted the need to develop global scientific objectives based on the best available scientific evidence for the adoption of healthy and sustainable diets.

Evolution of nutrition in the world in recent decades

Global nutrition policies follow a similar design and implementation, but the application and adaptation to the resources and dietary traditions of each country vary. Therefore, there are differences between different geographical areas:

  • In developed countries, nutritional deficiencies have been largely eliminated in recent decades, and the main concerns have focused on the prevention of diet-related diseases, such as cardiovascular diseases, with obesity being the biggest problem to tackle.
    Food policies have made efforts to promote more varied and balanced diets, with increased consumption of fruits and vegetables, avoiding diets high in fat, very high in energy and mainly consisting of foods of animal origin.
    "In Spain, for example, there has been a significant leap since the 1960s, where stronger commitments have been established with world organizations regarding policies, as well as studies, surveys, guidelines, and training on nutrition and its direct association with health," explains the specialist in scientific information.
  • In countries with high poverty rates, the food consumption pattern is characterized by a monotonous diet with a small amount of animal products, high carbohydrate and fiber intake with low protein content, leading to protein, mineral, or vitamin deficiencies. In these countries, nutrition policies and programs focus on ensuring access to foods that provide variety and specific nutrients to prevent malnutrition. They also address the prevention of infectious diseases through hygiene and sanitation.

Factors that affect nutritional status

Although progress has been made in reducing nutritional problems and success has been achieved in managing hunger and malnutrition in many countries, there are still factors that significantly impact nutrition trends worldwide.


Globalization has allowed for the availability of a wide variety of foods in all parts of the world. This has had both positive and negative consequences. For example, it has allowed for the export and access to a greater variety of fresh and nutritious foods in areas where they were previously unavailable. But it has also contributed to the loss of diversity in local foods in certain communities in favor of increased consumption of processed foods.

Climate change

Climate change has negatively affected food production, limiting the availability and accessibility of certain nutrient-rich foods. Additionally, extreme weather events such as droughts and floods have affected crop production, resulting in a decrease in the amount of food available worldwide.

Western consumption habits

The consumption habits of Western countries have shifted towards an increase in high-fat, high-sugar, and high-salt foods, contributing to the prevalence of non-communicable diseases such as obesity and diabetes.


Conflicts and humanitarian crises can also have a significant impact on global nutrition. For example, armed conflicts can disrupt food production and distribution in certain regions, exacerbating malnutrition in those areas.

What challenges and solutions exist to improve global and local nutrition?

Both specialists agree that important changes have occurred in dietary patterns. "Society has experienced an increase in the consumption of processed and low nutritional quality foods. This has contributed to the growth of obesity rates and chronic diseases such as diabetes and cardiovascular diseases," says María Mercedes Sánchez, responsible for Scientific Information.

Fortunately, as Dr. Acosta adds, "in recent years we have seen a positive trend in society towards being more critical and selective with their diet and lifestyle, focusing on the quality of food and analyzing what we eat.

For example, the “real-food” movement and similar ones have emphasized the importance of consuming fresh and unprocessed foods. These movements also promote nutritional education and learning how to read food labels and choose healthier options."

As a result, more and more people are paying attention to the quality of the food they consume and taking steps to improve their diet and overall health.

However, challenges for public health are significant on a global level.

"There are still serious nutritional deficiencies in countless countries and geographic areas, requiring coordinated and strategic action to promote nutritional education at all levels, as well as improve the availability and access to healthy foods.

Regulating food advertising is also essential. Additionally, it is crucial to continue advancing research and education on nutrition and health to develop effective policies and strategies that promote healthy eating and lifestyle habits," says Dr. Acosta.

Trending diets: characteristics, advantages, and disadvantages

Trendy foods

Diets aim to achieve a good energy balance, maintain weight, and establish healthy eating habits. The diet, in its most accurate definition, is one that meets nutritional needs, is harmless, and promotes health and well-being.

In general, to have a balanced, healthy, and weight-maintaining diet, three fundamental aspects must be considered:

  • Monitoring the amount of food ingested through hypocaloric, very hypocaloric, or replacement diets.
  • Observing the type of foods consumed (composition in macronutrients), such as low-carbohydrate, low-fat, or protein-based diets.
  • Paying attention to meal timing.

Due to campaigns on weight, lifestyle, and health, there has been an explosion of dietary recommendations that often have little scientific evidence, coupled with society's great ignorance about guidelines and nutritional recommendations by experts.

Fad diets

An example of this is the so-called "fad diets" that, with little or no scientific basis, claim to have unproven qualities that are not in line with current nutritional knowledge or exaggerate properties and effects that are not evident or proven. Examples of these diets are the Dukan diet, dissociated diet, or the known as the baby food diet.

Scientifically-based diets

Among the diets recognized and endorsed by nutrition professionals are the Mediterranean diet, DASH (to prevent hypertension), "veggie" diets, those focused on gut microbiota (FODMAP), the ketogenic or keto diet, intermittent fasting, and the paleolithic or paleo diet, among others.

Let's review some of them and then take a closer look at the last three.

Mediterranean diet

It has proven effective for weight loss and the prevention of cardiovascular diseases and is backed by sufficient evidence. It is characterized by a high consumption of plant-based foods such as fruits, vegetables, whole grains, legumes, nuts, and olive oil, and moderate consumption of fish, poultry, and dairy products, with occasional consumption of red meat. Spanish nutrition guidelines recommend it along with an active and social lifestyle, with regular physical activity and the importance of sharing meals with friends and family.

Veggie diets

"Veggie" diets focus on reducing the intake of animal products and minimizing the environmental impact.

They are classified as flexitarian, vegetarian, and vegan. It is a flexible diet in which mainly plant-based foods and beverages are consumed, incorporating dairy and eggs and consuming meat less frequently or in smaller portions.

In Spain, over 10% of the population declares themselves flexitarian according to recent surveys.

Anti-inflammatory diet

Chronic inflammatory processes increase the risk of insulin resistance, diabetes, or cardiovascular diseases, among others. Therefore, modulating inflammation is important for prevention and treatment.

There is sufficient scientific evidence on the important role certain nutrients or foods play in acting as anti-inflammatory agents (for example, omega 3) or proinflammatory agents (such as simple sugars and refined grains).

Therefore, the anti-inflammatory diet focuses on excluding these refined sugars, processed foods, and saturated fats, and prioritizes fruits, vegetables, healthy fats, and lean proteins. This diet requires an initial evaluation and follow-up by a qualified professional.


It is a therapeutic diet, as it is used to control gastrointestinal symptoms that are accompanied by inflammation (abdominal pain and bloating, diarrhea), dyspepsia (heartburn, slow gastric emptying), and reflux (burping).

The FODMAP diet focuses on identifying if fermentable carbohydrates cause symptoms, and then defining the appropriate ingredients for the regular diet.

This diet should be supervised by a qualified professional.

Keto Diet: What is it and can it help you lose weight?

It is important to remember that before starting any diet, it is important to consult with a healthcare professional to evaluate if it is suitable for our specific needs and goals.

What is the keto diet?

The ketogenic diet, also known as the Keto diet, is characterized by an extreme reduction in carbohydrate intake (less than 50 grams per day) and a relative increase in proportions of proteins and fats. "This induces a state of ketosis in the body, in which the body burns fat as the main source of energy instead of carbohydrates, and can reduce appetite and increase satiety due to proteins," explains Dr. Acosta, nutritionist and sports doctor.

What are the benefits of the keto diet for health and weight?

The keto diet has been used as a special type of therapeutic nutrition for epilepsy, metabolic and neurological disorders, with good results. In fact, there are four different versions of personalized keto diets for therapeutic effect: the "classic" (KD), medium-chain triglycerides (MCT), modified Atkins (MAD), and low glycemic index (LGIT).

Recently, it has been found that it can provide value in weight loss, especially due to its action in appetite reduction and triglyceride reduction.

"A meta-analysis by the Journal of Lipids and Nutrition concluded that there are indeed weight reductions comparable to other diets, although there are mixed results regarding its usefulness in reducing cholesterol or other cardiovascular risk factors," explains specialist in scientific information, Maria Mercedes Sánchez.

And she adds that, "the data from long-term clinical studies is not sufficient, which is why more research is needed."

What are the risks or drawbacks of the keto diet?

"The keto diet is difficult to maintain over time, especially if it is 100% restrictive, as it can result in deficiencies in vitamins and minerals (found in fruits and vegetables), especially when the diet has not been established with specialized advice," says Dr. Acosta.

"It is important to note that research on the keto diet is still ongoing, so it is essential to be advised by a nutritionist," adds Maria Mercedes Sánchez.

Paleo Diet: What is it and how is it based on ancestral nutrition?

The Paleo diet is based on the idea that we should eat like our prehistoric ancestors, hunters and gatherers. This diet obtains 35% of calories from fats, another 35% from carbohydrates (mainly fruits and vegetables), and 30% from proteins. Thus, this diet recommends the consumption of lean meat, fish, vegetables, fruits, and nuts, avoiding grains, dairy products, processed and refined foods, as well as added sugar and salt.

What are the benefits of the Paleo diet for health and weight?

Evidence from studies indicates that this diet favors weight loss, especially in terms of waist and hip circumferences, induces satiety, and improves insulin sensitivity, which helps control blood sugar.

"By proportionally focusing on carbohydrates, fats, and proteins, it can help increase the feeling of satiety and reduce calorie intake. However, it is important to note that although it is the diet of our ancestors, we must remember that hunting techniques (physical exercise) are no longer carried out, raising and cooking techniques have changed, as well as our microbiota, so long-term scientific evidence will confirm the health benefits,"

says Dr. Acosta.

As with other trendy diets, "the scientific evidence is recent and has been compared to other diets, such as the Mediterranean diet, finding that weight reductions are comparable, although adherence to the Paleo diet is lower," says Maria Mercedes Sánchez.

What are the risks or drawbacks of the Paleo diet?

Regarding the risks or deficiencies of this diet, we find that "some experts question whether this diet is a sustainable and healthy form of long-term nutrition because it limits the consumption of calcium-containing products and includes the consumption of saturated fats," explains Maria Mercedes Sánchez.

Intermittent Fasting: What is it and how does it affect cholesterol and blood pressure?

Intermittent fasting (Intermittent Fasting (IF)) involves alternating periods of fasting with periods of eating.

Instead of focusing on calorie counting or macronutrient composition, it focuses on the time interval in which we eat. During non-fasting days, "food consumption can be at will, restricted to a certain diet composition, or aimed at achieving a specific caloric intake.

Types of Intermittent Fasting

There are several types of intermittent fasting:

    • 16/8 Method, which involves fasting for 16-18 hours a day.
    • 5:2 Method, fasting or consuming 900-1000 calories for two non-consecutive days a week.
    • Complete fasting for 24 hours, once or twice a week.

What are the benefits of intermittent fasting for health and weight?

Advocates of intermittent fasting suggest that it could benefit patients with weight problems and has effects comparable to daily calorie restriction; it can also improve physical and cognitive functions and have positive effects on metabolism and the immune system.

Its positive effects on weight loss are attributed to the fact that "with intermittent fasting, calorie intake is reduced by limiting the available time for eating, which can lead to a decrease in total food consumption and therefore weight loss. In addition, intermittent fasting can promote the burning of fats as a source of energy during the fasting period," explains the doctor and nutritionist.

Regarding its effects on brain function, "this is because it improves neurological processes and has a positive impact on verbal, executive, working memory, and cognitive functions in general," explains Maria Mercedes Sánchez.

However, "more evidence is needed on the long-term sustainability and health effects of this type of fasting," adds the specialist in scientific information.

What are the risks or drawbacks of intermittent fasting?

Just as the benefits need to be evaluated, "special attention should be paid to patients undergoing hypoglycemic treatment, as fasting can cause dizziness, general weakness, bad breath, headache, chills, and lack of concentration, although no serious adverse effects have been described; a nutritionist is key to ensuring that the nutritional needs of the individual are met, as well as providing advice and ongoing education," says Maria Mercedes Sánchez.

Recommendations from Dr. Yaiza Acosta, nutritionist and doctor

After analyzing nutrition today and trendy diets, Dr. Yaiza Acosta provides us with a series of recommendations for maintaining a healthy diet.

1. Do you recommend trendy diets to your patients?

Trendy diets are, for me, a technique to educate patients on how to eat and choose the products their body needs. We can adapt them to their schedule, routines, sports activities, etc. But, as their name implies, they are "fad diets," difficult to maintain over time. That's why I only use them as a tool.

2. What advice would you give someone who wants to improve their nutrition?

First, I would congratulate them for taking that step, and then I would advise them to seek the advice of a nutritionist to determine which regimen is best suited to their needs and is compatible with their medical conditions, energy requirements, physical activities, and lifestyle.

3. What foods are essential in a balanced diet?

I would say that there is no ideal or essential food, but to maintain a balanced and healthy diet, it is important to base it on the consumption of fish, quality red meat, different types of vegetables, and nuts.

4. What eating habits should we avoid?

The one that requires the most consideration, in my opinion, is the consumption of ultra-processed and fast food products, such as industrial pastries. Due to the pace of life we lead, these types of products occasionally come in handy, but if we consume them daily, we are filling ourselves with empty and unsatisfying calories.

Also, soft drinks and "light" foods contain some sweeteners that can alter our gut microbiota.

And, of course, alcoholic beverages, which, in addition to the health problems they can cause, contain a large number of calories that can lead to weight gain.


Finally, it is important to educate the population more and better to dispel false food myths, such as believing that whole wheat bread is less fattening than white bread. The reality is that both have the same number of calories, the only difference is that whole wheat bread has much more fiber.


Content created with the collaboration of the responsible person in the area of Scientific Information at MARNYS and the collaboration of Dr. Yaiza Acosta. This article is for informational purposes only and does not replace the consultation with a specialist.

Dra. Yaiza AcostaAbout the specialist

Dra. Yaiza Acosta @dra_saludable

Dra. Yaiza Acosta is a medical doctor specialized in physical medicine and sports, as well as nutrition and applied dietetics. She promotes a healthy lifestyle through her social media channels as @dra_saludable.

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