The Paleolithic diet and the Mediterranean diet are propagated without real scientific evedence. They beared on absolutely different ideas as temporary fashions and are not well accompanied with biological or medicinal performance tests.

In contrast the ketogenic diet is a medicinal therapy as a treatment for special diseases. This diest is allowed only with medical examinations and supervision.

The Paleolithic diet and the Mediterranean diet are propagated without real scientific evedence. They beared on absolutely different ideas as temporary fashions and are not well accompanied with biological or medicinal performance tests.

In contrast the ketogenic diet is a medicinal therapy as a treatment for special diseases. This diest is allowed only with medical examinations and supervision.

I would tend to disagree with the comment that the "Mediterranean Diet" is either temporary or without scientific evidence--a pubmed search of Mediterranean Diet Health brings up over 1200 articles. The ketogenic diet has been use to control epilepsy with fairly good success. The Mediterranean Diet is associated with health benefits for a number of diseases/disorders including but not limited to (cardiovascular disease, obesity, metabolic syndrome, diabetes, cancer, aging, Alzheimer and other neurodegenerative disorders. depression, bipolar, schizophrenia, an ultimately--it reduces mortality risk.

Here is just a sampling Meta Analyses on clinical/epidemiological evidence for benefits of the Mediterranean diet--(a number of studies have also been done in animal models).

The effect of Mediterranean diet on metabolic syndrome and its components: a meta-analysis of 50 studies and 534,906 individuals.

C. M. Kastorini et al. J Am Coll Cardiol. (2011)

Primary Prevention of Cardiovascular Disease with a Mediterranean Diet

E. Ramón et al. N Engl J Med (2013)

Mediterranean diet and stroke, cognitive impairment, depression: A meta-analysis

T. Psaltopoulou et al. Ann Neurol (2013).

Mediterranean Diet, Cognitive Function, and Dementia

I. Lourida et al. Epidemiology (2013)

Mediterranean dietary pattern and prediction of all-cause mortality in a US population: results from the NIH-AARP Diet and Health Study.

P. N. Mitrou et al. Arch Intern Med. (2007)

Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial

M. Guasch-Ferré et al. BMC Medicine (2013)

Regarding your question about carbohydrates/grains, there isn't a lot of data out there (med diets are better than high carb, low fat diets in general). Although there is less evidence, low carb/ketogenic/atkins style diets have similar health benefits as a Med diet--despite a large discrepancy in the macro and micronutrient profile, particularly carbohydrate content. The rationale behind the Paleo diet, from my understanding, suggests the difference between Unhealthy and healthy diets lies in whether carbs/grains (and dietary constituents in general) are highly processed/refined--as a side note I do agree that this (Paleo) diet is a bit of a fad with little empirical evidence-- there is a previous discussion on the topic in the forums.

This article suggests an additive benefit from low carb + Med style diet for diabetes.

http://www.sciencedaily.com/releases/2013/08/130815203715.htm

http://www.ncbi.nlm.nih.gov/pubmed/?term=Mediterranean+diet+and+glycaemic+load+in+relation+to+incidence+of+type+2+diabetes%3A+results+from+the+Greek+cohort+of+the+population-based+European+Prospective+Investigation+into+Cancer+and+Nutrition+%28EPIC%29

To move beyond all the "correlations" to real evidence, its going to be important to critically define these diets at a biochemical level: total calories,macronutrient and micronutrient content, and the levels of intake of each of these classes....beyond that, we need to figure out the best biomarkers quantify changes that track with and predict the ultimate effects on end point clinical parameters associated with a given disease.

Ultimately, I think this is the right sort of question to be asking--as it highlight a major issue in interpreting and gaining meaningful insight about the mechanisms involved in dietary effects from human "epidemiological" evidence.

With the term "Diet" we mean "what we eat", but its real mean is "way of life".

The so called Mediterranean Diet was born by scientific observations of prpf Ancel Keys, a physiologist and epidemiologist that has devoted the greatest part of his studies on the field of nutrition (he has also invented the world famous military K-ration, K as Keys). A convergence of evidence (see above) has shown its benefical effects. However the way of life of mediterranean people has changed in last 70 years, and a lot of foods with an high glicemic index was introduced in their daily meals, reducing the benefits that keys observed in his permanence in south of Italy.

Paleo diet is born by a theoretical assumption, valid but theoretical. Paleolitic way of life was very different by ours, as their life expectancy. Are we sure it is necessary a good diet? I don't know.

Ketogenic diet, as we currently knows, is an high fat, low carb diet, adopted to treat epilepsy (and other neurological conditions). However, a lot of peoples adopt for a good part of the year this kind of diet, but they do not know. It is the case of Alaska and Siberia People, or in several pacific islands. Ketogenesis is not induced by high fat assumption that is not mandatory (see ketogenic VLCD), Maybe a genetic adaptation occurred in that lands in which the diet is substantially low carb!

Also Vegan diet could be worth of a deepen discussion, since it is very safe and helth is poor simple rooles are observed!

Maybe it does not exist the best diet, but exists some useful rooles as the avoidance of high glicemig index foods, the caloric restriction the good balance of micro and macro nutrients, etc.

The Mediterranean diet is not effective. The ketogenic diet is more effective, but some reasons that lead to disease can not be restored. The ketogenic Paleolithic diet can restore the abnormal intestinal permeability as well. Therefore suitable for curing autoimmune diseases.

https://www.researchgate.net/profile/Csaba_Toth9/contributions

Dear Heidi Kocalis, there is evidence supporting the paleo diet. Please see recent meta-analysis on paleo diets and metabolic syndrome:

http://ajcn.nutrition.org/content/early/2015/08/12/ajcn.115.113613

And just "some" more references, (not updated in almost one year, with more evidence showing up).

http://oscarpicazo.es/2015/04/08/paleodiet-101/

We need more well designed RCTs in order to keep advancing. Mediterranean is better than western diet, but, could it be improved? We do not know yet, there is still much to know.