The Mediterranean Diet first came to prominence around 50 years ago. It was first observed that people in Mediterranean countries such as Greece and Italy had lower mortality rates from cardiovascular diseases compared with people in other European countries. Given the importance of diet as a risk factor for cardiovascular disease it was suggested that this reduced mortality may be due to different dietary habits. Large population studies have also found that as well as a reduced risk of death from heart disease, this diet may also protect against cancer, Parkinson's disease and Alzheimer's disease.(http://www.aimedjournal.com/article/S2212-9626(13)00015-1/pdf)
There is a debate as to what the Mediterranean diet actually is, because we know the Greeks eat quite differently to the Italians, and both eat differently to the French and Spanish.
However the Harvard School of public Health developed a Mediterranean Food Diet pyramid.
The agreed version is that the diet emphasises eating fruits and veggies, whole grains, beans, nuts, legumes, olive oil and flavourful herbs and spices. Seafood is encouraged at least a couple of times a week, but also cheese, poultry, eggs and yoghurt are common in moderation, with sweets and red meats often saved for special occasions.
DON’T FORGET the wine however, a splash of wine with food is very common in the Mediterranean diet.
The Mediterranean diet has never emphasised calorie intake but there is some promising research on weight loss.
A 2016 study in The Lancet - Diabetes & Endocrinology journal that analysed data from Predimed – a five-year trial including 7,447 adults with Type 2 diabetes or at risk for cardiovascular disease. Those taking part were assigned either a Mediterranean diet supplemented with olive oil, the same diet supplemented with nuts or a control diet. They found that people on the Mediterranean versions added the fewest inches to their waistlines. The olive oil folks lost the most weight. http://www.thelancet.com/journals/landia/article/PIIS2213-8587%2816%2930085-7/abstract
Advantages – The diet plan is relatively easy to follow, the diet does not ban entire food groups so long term compliance is perhaps more achievable. The Mediterranean diet, although difficult to easily define is one of the most researched diets of all time, and purported health benefits, especially in relation to cardiovascular health have been suggested throughout multiple studies.
The richness and variation of ingredients, and consumption of palatable foods mean very few people complain about blandness or taste fatigue problems with a Mediterranean style of eating. There is also decent research to suggest this style of eating can be adhered long term.
Disadvantages - Perhaps certain common ingredients in certain parts of the world (olive oil, nuts, fish and fresh produce) are a little on the expensive side.
A 2010 study in Diabetes, Obesity and Metabolism assigned 259 overweight diabetics to one of three diets: a low-carb Mediterranean diet, a traditional Mediterranean diet or a diet based on recommendations from the American Diabetes Association. All groups were told to exercise 30 to 45 minutes at least three times per week. After a year, all groups lost weight; the traditional group lost an average of about 16 pounds while the ADA group dropped 17 pounds and the low-carb group lost 22 pounds. https://www.ncbi.nlm.nih.gov/pubmed/20151996
Another study, published in the New England Journal of Medicine in 2008, assigned 322 moderately obese adults to one of three diets: calorie-restricted low-fat; calorie-restricted Mediterranean; and non-calorie-restricted low-carb. After two years, the Mediterranean group had lost an average of 9 7/10 pounds; the low-fat group, 6 4/10 pounds; and the low-carb group, 10 3/10 pounds. Although weight loss didn't differ greatly between the low-carb and Mediterranean groups, both lost appreciably more than the low-fat group did. http://www.nejm.org/doi/full/10.1056/NEJMoa0708681#t=article
A 2008 analysis of 21 studies in the journal Obesity Reviews concluded the jury is still out on whether following the Mediterranean diet will lead to weight loss or a lower likelihood of being overweight or obese. https://www.ncbi.nlm.nih.gov/pubmed/18547378
In fact from the paper itself
“We identified 21 epidemiological studies that explored the relationship between the Mediterranean diet and weight. These included seven cross-sectional, three cohort and 11 intervention studies. Of these, 13 studies reported that Mediterranean diet adherence was significantly related to less overweight/obesity or more weight loss”
So it seems as with every diet, adherence is the biggest factor in achieving results. And finally, arguably the gold standard of science reviews, the Cochrane collaboration conclude
“The limited evidence to date suggests some favourable effects on cardiovascular risk factors. More comprehensive interventions describing themselves as the Mediterranean diet may produce more beneficial effects on lipid levels than those interventions with fewer dietary components.”
To Sum It Up
So, it’s hard to argue against this diet as a “healthier” diet compared to most, but for weight loss should be followed with a caloric deficit in mind. There are certain elements to the Mediterranean lifestyle (social activites, community, physical activity etc) which may also play a part in their impressive lifespan but there is no doubt the Mediterranean diet is a viable option to try with potential health benefits more so than most diets.