Low-carbohydrate and Mediterranean diets are two popular approaches to healthy eating, but they differ considerably in their emphasis.
A Mediterranean diet generally emphasizes vegetables, fruits, legumes, whole grains, nuts, olive oil, and fish, while limiting highly processed foods and red meat. It has extensive research supporting benefits for cardiovascular health and is widely recommended by medical organizations.
A low-carbohydrate diet limits sugars and starches and generally emphasizes protein, fats, and non-starchy vegetables. Very-low-carbohydrate ketogenic diets reduce carbohydrates enough to produce ketones. Research has shown that low-carb diets can improve blood glucose, triglycerides, weight, and insulin resistance, particularly in people with metabolic problems.
Both approaches can be healthy. An important question is whether one works better than the other for particular people—and whether the best diet may depend on an individual's metabolic health, preferences, and ability to sustain it.
The Mediterranean diet has become one of the most widely recommended eating patterns in medicine. Its strongest evidence comes from studies of cardiovascular disease, longevity, and overall health. It emphasizes food quality rather than strict limits on calories or carbohydrates.
Low-carbohydrate diets take a different approach. They focus particularly on reducing foods that raise blood glucose and insulin, including sugar, refined carbohydrates, and, at lower carbohydrate levels, many grains and starchy foods. They generally allow more meat, eggs, dairy, and fat than traditional Mediterranean diets.
The two approaches also have considerable overlap. Both can emphasize vegetables, fish, nuts, olive oil, minimally processed foods, and avoiding added sugars and ultra-processed foods.
The major difference is usually the amount of carbohydrate. That makes head-to-head studies particularly useful in asking whether carbohydrate restriction provides benefits beyond simply eating better-quality food.
The Mediterranean diet is widely recommended by major medical and public-health organizations.
The American Heart Association recommends a Mediterranean-style eating pattern for cardiovascular health. The American Diabetes Association includes Mediterranean-style eating among the dietary patterns that can help people with diabetes or prediabetes. Harvard's T.H. Chan School of Public Health describes the Mediterranean diet as a healthy eating pattern supported by research on cardiovascular disease and overall health.
The diet also consistently receives high rankings from nutrition experts and has become, for many physicians, a model of what a healthy diet should look like.
That makes comparisons with low-carbohydrate and ketogenic diets especially important. The question is not whether the Mediterranean diet is healthy—it clearly can be—but whether greater carbohydrate restriction may provide additional benefits for people with Insulin Resistance or other metabolic problems.
Low-carbohydrate diets have increasingly moved into mainstream medicine, particularly for type 2 diabetes, obesity, and metabolic disease, although they are not recommended as universally as the Mediterranean diet.
The American Diabetes Association recognizes low-carbohydrate and very-low-carbohydrate eating patterns as options for some people with diabetes. A growing group of physicians and researchers—including Eric Westman, Gary Taubes, Ben Bikman, and Nick Norwitz—argue that carbohydrate restriction can be particularly effective for people with Insulin Resistance and elevated blood glucose.
Low-carb advocates emphasize reducing sugar, refined carbohydrates, and starches that can raise blood glucose and insulin. Some recommend moderate carbohydrate restriction, while others favor a very-low-carbohydrate ketogenic diet.
The continuing debate is not simply about whether low-carb diets can work. It is about how they compare with other healthy diets, who benefits most, and what happens over the long term.
A recent randomized clinical trial directly compared three calorie-restricted diets in people with metabolically unhealthy obesity, prediabetes, and excess liver fat: a very-low-carbohydrate ketogenic diet, a Mediterranean diet, and a very-low-fat diet.
Unlike many nutrition studies that depend heavily on participants reporting what they ate, this was a controlled feeding study, giving researchers much greater control over the foods consumed.
After six months, participants in all three groups lost substantial weight—about 10% of their starting body weight. Because weight loss was similar among the groups, researchers could better examine whether the composition of the diets produced different metabolic effects.
The ketogenic group showed greater improvements in several important measures, including hepatic Insulin Resistance, liver fat, HbA1c, and 24-hour blood glucose and insulin levels.
The results are particularly noteworthy because the comparison was not between a ketogenic diet and a poor-quality standard diet. The ketogenic diet was being compared with a Mediterranean diet—one of the most respected and widely recommended dietary patterns in medicine.
Effect of Diet Macronutrient Content on the Cardiometabolic Response to Weight Loss
A randomized clinical trial comparing very-low-carbohydrate ketogenic, Mediterranean, and very-low-fat diets in people with obesity, prediabetes, and excess liver fat. All groups achieved similar weight loss, allowing researchers to examine whether the composition of the diet produced different metabolic effects.
Dr. Norwitz summarized the trial with the provocative headline “Keto Won.” On several important metabolic measures, that is a reasonable interpretation of the results.
Despite similar weight loss, the ketogenic group had greater improvements in liver fat, blood glucose, hepatic Insulin Resistance, HbA1c, and 24-hour glucose and insulin levels.
There was also an interesting finding concerning cholesterol. Despite consuming considerably more saturated fat and dietary cholesterol, the ketogenic group did not have a significantly worse change in ApoB than the other groups.
I find Dr. Norwitz particularly good at providing a nuanced analysis of research, and his “Keto Won” headline comes with important context. The participants had obesity, prediabetes, and excess liver fat. The study does not establish that a ketogenic diet is superior for people who are already metabolically healthy, nor does a six-month trial answer questions about long-term health.
Perhaps the most important conclusion is that the best diet may depend partly on the metabolic health of the person eating it.
Nick Norwitz, M.D., Ph.D. — A Major Trial Put Keto Against the Mediterranean Diet. Keto Won.
Dr. Norwitz explains the trial’s results and argues that the ketogenic diet’s metabolic advantages illustrate why the healthiest diet may depend on an individual’s metabolic condition.
This was an unusually informative nutrition trial because the researchers controlled the food participants received and achieved similar weight loss across the three diets. That makes it easier to separate the effects of diet composition from the effects of weight loss itself.
For people with obesity, prediabetes, and excess liver fat, the results provide strong evidence that very-low-carbohydrate ketogenic eating can produce substantial metabolic improvements, and on several measures greater improvements than a Mediterranean diet.
But the study lasted only six months and involved a specific group of people with significant metabolic problems. It does not tell us whether keto is better for people who are already metabolically healthy, whether the advantages persist for years, or which diet is easier to maintain over the long term.
Nor does one trial overturn the large body of evidence supporting Mediterranean-style eating, particularly for cardiovascular health.
The study therefore strengthens the case for considering metabolic health when choosing a diet, rather than assuming that one dietary pattern is best for everyone.
• Both Mediterranean and low-carbohydrate diets can be healthy, and they share an emphasis on whole, minimally processed foods.
• The Mediterranean diet has extensive research supporting cardiovascular health and is widely recommended by major medical organizations.
• Low-carbohydrate diets are increasingly recognized as an option for type 2 diabetes, obesity, and metabolic disease, particularly for people with Insulin Resistance.
• In a six-month controlled feeding trial, ketogenic, Mediterranean, and very-low-fat diets produced similar weight loss, but the ketogenic diet produced greater improvements in several measures of metabolic health.
• The participants had obesity, prediabetes, and excess liver fat, so the results should not automatically be generalized to metabolically healthy people.
• The trial suggests that diet quality matters, but so may diet composition and an individual’s metabolic condition.
• Rather than asking which diet is universally “best,” a better question may be: Which diet works best for which person?
An overview of the Mediterranean eating pattern and why the American Heart Association recommends it for cardiovascular health.
The American Diabetes Association describes low-carbohydrate and very-low-carbohydrate eating patterns as evidence-based options that may improve blood glucose, weight, triglycerides, blood pressure, and HDL cholesterol.
A 2026 scientific review examining how differences in Insulin Resistance, glucose metabolism, genetics, and the gut microbiome may help explain why people respond differently to the same diet.
A discussion of research comparing ketogenic and Mediterranean diets and how differences in blood glucose, metabolic health, and cholesterol can affect the interpretation of the results.
Dr. David Katz discusses Mediterranean and ketogenic diets from a preventive-medicine perspective and considers whether overall diet quality may matter more than choosing one dietary label over another.
Gary Taubes makes the case for carbohydrate restriction and ketogenic diets, focusing on insulin, fat storage, metabolic health, and why reducing carbohydrates may benefit people with Insulin Resistance.