In Spain, we are bombarded with messages about diets, weight-loss tricks, and miracle methods that, far from clarifying things, often generate more questions. Among so many options, three approaches are repeatedly mentioned in consultations, the media, and social networks: the Mediterranean diet, the Atlantic diet, and intermittent fasting.
To bring some order to this debate and bring things down to earth, the Spanish Society for the Study of Obesity (SEEDO) has reviewed the available scientific evidence on these three models. The goal is not to promote a fad diet, but to determine which nutritional strategy works best for preventing and treating overweight and obesity in the population, especially within the Spanish and European context.
Mediterranean diet: the pattern best supported by science
The Mediterranean diet, as studied in depth, has little to do with simplified versions that reduce everything to olive oil or eating pasta. It is a pattern based on a high consumption of fruits, vegetables, legumes, and whole grains , accompanied by regular fish and olive oil as the main source of fat.
This dietary pattern is characterized by its richness in unsaturated fats, high-quality carbohydrates, fiber, and phytochemicals , elements that work together to reduce inflammation and oxidative stress, and improve insulin sensitivity. As Professor Jordi Salas-Salvadó explained, adherence to the traditional Mediterranean diet is associated with a lower risk of obesity, weight gain, and type 2 diabetes , as well as a positive impact on cardiovascular disease, some types of cancer—such as breast cancer—and cognitive decline.
When adapted to a weight-loss context, a slightly hypocaloric version is usually used , meaning an energy intake somewhat lower than the person's needs, while maintaining the structure and quality of the diet. This combination, along with regular physical activity, is considered the best strategy for weight loss in overweight or obese individuals , while also improving risk factors such as blood pressure, triglycerides, HDL cholesterol, inflammation, and insulin resistance.
Available research indicates that the Mediterranean diet offers superior results compared to very low-fat or very low-carbohydrate diets . Furthermore, clinical trials show that this dietary pattern can reverse metabolic syndrome, a cluster of conditions (abdominal obesity, hypertension, dyslipidemia, and insulin resistance) that increase the risk of heart attack, stroke, and diabetes.
Despite all this, this dietary model is being abandoned in Spain , especially among children, teenagers, and young adults. Older people, particularly women over 65, are the ones who maintain the best adherence. Behind this change lie factors such as a fast-paced lifestyle, the loss of culinary traditions, and the spread of Western eating patterns rich in processed and ultra-processed products , at the expense of fresh foods.
The weight of evidence: PREDIMED, PREDIMED-Plus and international assessments
Beyond theory, the strength of the Mediterranean diet is supported by large studies carried out in Spain and independent international assessments.
PREDIMED-Plus, coordinated by the Rovira i Virgili University and involving more than 6.000 participants followed for approximately eight years , compared various lifestyle interventions. The results confirmed that the combination of a low-calorie diet, physical activity , and behavioral support achieves greater weight loss and a more significant reduction in cardiovascular risk factors (such as obesity, elevated glucose, and high triglycerides) than the Mediterranean diet alone, without calorie restriction or intensive support.
Furthermore, this approach showed benefits in preserving lean mass and lumbar bone density , parameters that typically decline with age and can worsen when weight loss is achieved through highly restrictive or poorly planned strategies. In this regard, a well-designed hypocaloric Mediterranean diet is considered one of the options that best balances long-term efficacy and safety.
Recognition of this pattern is not limited to the national level. In a comprehensive evaluation conducted in the United States, a panel of dozens of nutrition and dietetics experts analyzed more than thirty diets based on their nutritional quality, safety, ease of maintenance, health effects, and scientific support . The Mediterranean diet emerged as the best overall option when all criteria were assessed together.
These conclusions are consistent with what was presented at the last SEEDO National Meeting, held in Toledo, where specialists from different Spanish universities agreed that the Mediterranean diet is the most solid strategy to prevent and treat overweight and obesity, provided that it is accompanied by regular physical activity and sustained changes in lifestyle.
Atlantic diet: a proximity model with comparable benefits
Alongside the Mediterranean diet, the Atlantic diet of southern Europe has been gaining prominence in scientific literature and expert forums. This diet is primarily associated with Galicia and northern Portugal and, like the Mediterranean diet, is based on a high consumption of fresh and minimally processed foods, but with its own distinct characteristics.
The Atlantic diet prioritizes seasonal and locally sourced products : fish and shellfish from both the sea and rivers, whole grains, dairy products—especially cheese—fruits, brassica vegetables (such as cabbage, broccoli, and turnip greens), chestnuts, olive oil, and spring water. It is a varied diet, rich in nutrients and containing numerous functional compounds that promote a more diverse and less dysbiotic gut microbiota.
It's not just about what you eat, but how that food is cooked and how it's shared . Traditional Atlantic cuisine favors methods like steaming, boiling, grilling, and stewing over frying, which helps reduce the energy density of the dishes. Furthermore, there's a strong tradition of meals with family and friends, where socializing around the table is an integral part of daily life.
Dr. Rosaura Leis, from the University Clinical Hospital of Santiago, emphasizes that the Atlantic diet cannot be separated from the "Atlantic lifestyle ," which also includes regular physical activity—often incorporated into the daily routine—and ensuring adequate sleep. According to her, this combination of factors has been linked to greater longevity and a better quality of life in the region.
Although studies on the Atlantic diet are less numerous than those on the Mediterranean diet, the available data point to comparable benefits in terms of cardiovascular health, weight management, and the prevention of chronic diseases . However, experts warn that this pattern is also declining, with a decrease in the consumption of fish, dairy products, fruits, and vegetables and an increase in ultra-processed foods from a very young age.
Intermittent fasting with a time window: a nuanced tool
As traditional diets lose ground, intermittent fasting has become one of the most talked-about strategies in recent years. Within this framework, there are various protocols, but the scientific community is particularly interested in what is known as Time Window Restriction (TRE).
This approach involves concentrating the intake of high-calorie foods and beverages within an 8-10 hour window each day , while fasting the rest of the time. In other words, the focus is not so much on what to eat, but rather when to eat. In practice, many people choose, for example, to start eating mid-morning and finish mid-afternoon or late afternoon, although the timings can vary.
According to Professor Idoia Labayen of the Public University of Navarre, the popularity of intermittent fasting has grown faster than the strength of the scientific evidence . Even so, available studies show that this strategy often leads to weight loss, largely because people almost automatically reduce their calorie intake when they have fewer hours to eat.
Weight loss with TRE is accompanied by improvements in some cardiometabolic health markers, such as blood pressure and certain lipid parameters . Furthermore, a specific type of fasting with an early window—that is, concentrating meals in the first hours of the day—appears to offer additional benefits in glucose regulation and insulin sensitivity, although these results are still considered preliminary.
Experts emphasize that intermittent fasting, like any other intensive nutritional intervention, should be supervised by healthcare professionals . If the quality of the diet within the fasting window is not carefully managed, it can worsen the overall nutritional profile; and if it is not combined with exercise, there is a risk of muscle loss. Furthermore, adherence in the medium term is often low , which makes it easier for some of the lost weight to be regained over time.
Obesity in Spain: beyond choosing a diet
This entire debate is taking place within a worrying context: obesity has become one of the main public health problems in Spain . It is estimated to affect around 18-19% of the adult population, and more than half are already overweight or obese, placing the country at levels that are alarming to scientific societies.
Strategies for addressing this reality always involve a healthy diet, regular physical activity, and sustained lifestyle changes . Experts remind us that there is no single diet that is universally perfect for everyone; genetic, cultural, environmental, and personal factors influence which pattern is most manageable and effective in each case.
Even so, clinical experience and large studies agree that the Mediterranean diet plays a central role as a reference point for the general population. Its combination of nutritional quality, scientific evidence, social acceptability, and long-term sustainability gives it an advantage over other more restrictive or complex approaches.
The Atlantic diet is emerging as an alternative model with local roots and very similar benefits, especially suitable in regions where its culinary tradition is more deeply ingrained. Meanwhile, intermittent fasting can be a useful tool for certain individuals, particularly when adherence to a conventional low-calorie diet is low, provided it is used with professional guidance and tailored to each person's circumstances.
SEEDO and other organizations emphasize the need to recover and protect traditional dietary patterns , strengthening nutritional education from childhood and facilitating environments that make fresh food more accessible. At the same time, they warn of the impact of advertising and easy access to cheap, ultra-processed foods, which are displacing home cooking and market produce.
Overall, current evidence suggests that both the Mediterranean and Atlantic diets offer a solid and sustainable framework for managing weight and cardiometabolic health in Spain and other southern European countries, while intermittent fasting can complement these strategies in specific situations, always under medical supervision. The key lies not only in choosing a dietary label, but in building a lifestyle that combines good nutrition, daily exercise, adequate rest, and professional support when needed.
