COMMENTARY

Does the Mediterranean Diet Prevent Obesity?

Caroline Apovian, MD

Disclosures

October 12, 2022

An introduction in a recently published review by Muscogiuri and co-authors states unequivocally that "it [obesity] is a chronic disease." Needless to say, a chronic disease like obesity, type 2 diabetes, or cardiovascular disease, can't be treated by diet alone. No reputable healthcare provider would tell a patient that, at least not for type 2 diabetes or cardiovascular disease.

Caroline Apovian, MD

On the other hand, recent evidence suggests that the Mediterranean diet can help prevent obesity, type 2 diabetes, and cardiovascular disease. The authors review studies that show that adherence to a Mediterranean diet even without energy restriction is associated with weight maintenance and not weight gain.

This comprehensive review discusses the Mediterranean diet's effect on weight, body composition, type 2 diabetes, nonalcoholic fatty liver disease, cardiometabolic risk factors, dyslipidemia, and cancer. The authors conclude that it is the healthiest diet available to prevent cardiovascular disease and type 2 diabetes.

In relaying the takeaway points of this review article to our patients, communication about exactly what was concluded here is very important.

There are two potential misinterpretations of the data presented:

  1. What is the Mediterranean diet? The authors admit that there is "no single definition but it generally consists of little amounts of red meat, low to moderate amounts of fish, poultry, and large quantities of fruit, vegetables, whole grains, and…unrestricted olive oil as a source of monounsaturated fatty acids."

    For most healthcare providers, this is very clear, however, it may be misinterpreted in by our patients in the United States and other areas where the Western diet is pervasive. The Western diet often includes highly processed and ultraprocessed foods.

    As our colleague David Heber, MD, PhD, once famously said, "now is not the time to introduce olive oil to the American diet." He meant that if you simply add olive oil to a diet that is already heavily supplemented with sugars and saturated fat, you may end up adding more calories to an already high-calorie diet.

    In our conversations with patients, we should relate what the Mediterranean diet is and what it isn't. The Mediterranean diet typically consists of lean proteins, fruits, vegetables, whole grains, nuts and olive oils, and little or no sugars or processed foods.

  2. We also need to consider the lack of evidence demonstrating that the Mediterranean diet is superior to other diets for weight loss. Without calorie restriction, the Mediterranean diet shouldn't be assumed to treat obesity because, as the authors make clear in the introduction, obesity is a chronic disease. We have already established that to treat obesity successfully, it must be treated with behavioral strategies plus medications or surgical interventions.

These points are crucial to the understanding that patients should have in seeking obesity treatment. It's certainly beneficial to make sure bread or cereal come from whole grains and that you use olive oil but that doesn't automatically generate into weight loss or weight maintenance.

Americans, much more than Europeans, are used to eating large portion sizes both at home and in restaurants. If the only item highlighted in reports and social media about the Mediterranean diet is that you can eat lots of olive oil and whole grains, it may send the wrong message to the American public.

How can we use evidence-based medicine to educate our patients about the role of behavioral interventions like diet in helping them lose weight and keep it off? I propose several educational parameters that might be helpful in counseling patients on the diet:

  1. Discuss the macronutrient content of the Mediterranean diet as defined by the authors but also stress eliminating added sugars and highly processed foods as much as possible.

  2. Portion size should be discussed in relationship to weight loss expected because the Mediterranean diet can prevent weight gain but not necessarily induce weight loss without a decrease in calories ingested.

  3. Include other evidence-based strategies such as what is known about another controversial topic: intermittent fasting. We know that if you limit your meal times to an 8- to 10-hour window (eg, 8 AM to 4-6 PM), this can reduce the number of calories you take in because the length of time you eat during the day is much shorter than the usual.

In an ideal world, we would be able to eliminate all processed foods from the planet and return to a time when farms produce health grains, fruits, and vegetables enough to feed all the humans on the planet, and lean protein is available through livestock and fish, etc. We're not going to be able to do this in the near future.

Therefore, what does prevention of obesity and related diseases look like for 2022 and beyond? How will we ensure that most people on the planet have available healthy foods, such as what is in the Mediterranean diet that these authors have reviewed?

Currently, we feed the billions of people on this planet (in addition to healthy diets like the Mediterranean diet) a potpourri of processed and ultraprocessed foods containing sugar, saturated fat, and refined flours. We have to find a way out of this conundrum or develop an antidote to processed foods.

Time will tell if this antidote will be the gut hormone analogs that have been developed and are being developed and studied for the treatment of obesity and cardiovascular disease that has emerged owing to the environment we live in.

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