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Your guide to the four most popular diets

Get the facts behind the headlines

Magazines, blogs, and news sites routinely report on new “it” diets. The stories feature ordinary people and superstars alike who have shed unwanted pounds—and fast—with this amazing trick! It seems too good to be true, but the pop culture reporting insists that the body you want is within reach if you make this small change or that one. So, do the most popular diets actually work? If so, what are the benefits and potential risks? We’re getting to the bottom of it.

What to know before trying a popular diet

It’s important to understand what you are getting yourself into when starting a new health regimen. Having all the facts before jumping in lets you evaluate whether you can be successful in keeping to it, leading to better results down the line. My recommendation is to think about whether a new diet is sustainable in the long term. Healthy eating plans that are heavily restricted can lead to slips and burnout fast!

Often, deciding on a diet based on the above criteria requires a shift in mindset. You should make the goal fueling your body, not restricting calories. When we focus on fueling our bodies with healthy and nutritious foods, weight loss often follows.

With that in mind, it’s time to stop thinking about diets as a restriction. Instead, consider them as sets of behaviors that help you fuel your body in a healthy way. Use “healthy eating patterns” instead of “diets.” These healthy eating patterns include things like plant-based diets or the Mediterranean diet. There are also ones that are more restrictive, like the ketogenic diet and intermittent fasting, but the goal of each is the same: to ensure that your body is fueled in a healthy way. If you are considering changing the way you eat, we’re here to help. Here’s what you need to know to decide if one of these popular diets is right for you.

Popular diets (a.k.a. healthy eating plans)

Plant based diet: Plant-based diets are growing in popularity because of the purported health benefits and potential for chronic disease reversal. A plant-based diet is a great example of a sustainable healthy eating pattern, as many people are able to stick with it for decades.  

  • Basics: A plant-based diet includes “nutrient-dense plant foods,” including vegetables, fruits, whole grains, nuts and seeds, beans, peas, lentils, and soybeans. It also focuses on consuming minimal processed foods, animal products, and oils.
  • Benefits: Studies have reported improved cardiovascular health, reduced risk of cancers, diabetes, obesity, and other chronic conditions.[2][4][8][11]
  • What to watch out for: It’s common for people to worry about protein deficiencies with plant-based diets. However, most individuals on plant-based diets get plenty of protein. There are tons of foods that are chockful of protein but contain no meat. As long as you’re making sure to include them in your meals, lack of protein should not be a concern.

Mediterranean diet: The Mediterranean diet is based on the traditional eating patterns of populations along the Mediterranean Sea. It’s commonly regarded as uniquely well-balanced and satisfying with its focus on lean fats, fruits and veggies, and fish. As with the plant-based diet, the Mediterranean diet is a great choice for long-term success.

  • Basics: The Mediterranean diet focuses on consumption of fruits, vegetables, whole grains, legumes, potatoes, nuts and seeds, limited animal products, wine (in moderation), and lots of healthy fats like the ones found in olive oil.
  • Benefits: This eating pattern has been known to reduce the risk of heart disease[5][9], stroke, cancer, and diabetes.It’s also been linked to longer life expectancy.[5]
  • What to watch out for: Since this eating pattern doesn’t follow portion recommendations, it is important to pay close attention to portion sizes to ensure moderation and avoid weight gain.

Ketogenic diet: The “keto” diet has become increasing popular over the past few years thanks to claims that it’s a fast, easy way to shed pounds. It’s more restrictive than those above, with a focus on high fat intake, and can be difficult for some to maintain long-term.

  • Basics: A ketogenic diet is a highly restrictive eating pattern focused on packing fats into your meals while strictly limiting carbohydrates and maintaining a moderate protein intake.
  • Benefits: The ketogenic diet has been used to help manage epilepsy and some studies[7] have shown it can be effective for treating obesity. Individuals have reported losing weight quickly when sticking with a strict keto diet, but evidence of long-term maintenance of weight loss is unproven at this time.[6][7]    
  • What to watch out for: There are some health risks to watch out for if you stick with keto for the long haul. These include vitamin and mineral deficiencies, kidney stones, and liver disease[6].This pattern of eating is not safe for everyone, and those with certain chronic conditions[6] should talk to their doctor before starting a keto regimen.

Intermittent fasting: Fasting has been around for much of human history, but intermittent fasting as a means for improving health has come into vogue in recent years thanks to the claims that it helps people shed pounds and improve their sleep[12]. While this pattern doesn’t restrict the types of food you eat, it is highly restrictive when it comes to the times at which you can eat those foods. For that reason, it may not be sustainable for an extended period.  

  • Basics: Intermittent fasting consists of “taking breaks from eating” for up to 24 hours once or twice a week. The type of fast and the time frame of the fast depends on the type of plan you are following.
  • Benefits: Some studies[1] have shown that intermittent fasting can improve biomarkers for various diseases, promote weight loss, and improve learning and memory function.
  • What to watch out for: Medical professionals have warned that intermittent fasting can encourage unhealthy or extreme eating behaviors, such as binge eating[1].

All four of these popular diets have pros and cons. They are not one size fits all, so you should consider your current habits, your goals, and the kind of changes you want to make before picking one to try. Allow yourself the freedom to experiment until you settle on the one that best fits your lifestyle—or a modified version of these that is unique to you! Of course, we’re here to help if you need it. UPMC Health Plan members are welcome to reach out to one of our health coaches to talk through the options that might work for you.


  1. Collier, R. (2013). Intermittent fasting: the science of going without. The Canadian Medical Association Journal (CMAJ).
  2. Craig, W. J., & Mangels, A. R. (2009). Position of the American Dietetic Association: vegetarian diets. Journal of the American Dietetic Association, 109(7), 1266-1282.
  3. Crous-Bou, M., Fung, T. T., Prescott, J., Julin, B., Du, M., Sun, Q., … & De Vivo, I. (2014). Mediterranean diet and telomere length in Nurses’ Health Study: population based cohort study. Bmj, 349, g6674.
  4. Esselstyn, C. B., & Favaloro, R. G. (1998). Introduction: more than coronary artery disease. American Journal of Cardiology, 82(10), 5-9.
  5. Harbard TH Chan School of Public Health (2018). Diet Review: Mediterranean Diet. Retrieved from:
  6. Gordon, B. (2019). What is the Ketogenic Diet? American Academy of Nutrition and Dietetics. Retrieved from: 
  7. Gupta, L., Khandelwal, D., Kalra, S., Gupta, P., Dutta, D., & Aggarwal, S. (2017). Ketogenic diet in endocrine disorders: Current perspectives. Journal of postgraduate medicine, 63(4), 242.
  8. Kim, H., Caulfield, L. E., Garcia‐Larsen, V., Steffen, L. M., Coresh, J., & Rebholz, C. M. (2019). Plant‐Based Diets Are Associated With a Lower Risk of Incident Cardiovascular Disease, Cardiovascular Disease Mortality, and All‐Cause Mortality in a General Population of Middle‐Aged Adults. Journal of the American Heart Association, 8(16), e012865.
  9. Lăcătușu, C. M., Grigorescu, E. D., Floria, M., Onofriescu, A., & Mihai, B. M. (2019). The Mediterranean Diet: from an environment-driven food culture to an emerging medical prescription. International journal of environmental research and public health, 16(6), 942.
  10. Salas-Salvadó, J., Becerra-Tomás, N., García-Gavilán, J. F., Bulló, M., & Barrubés, L. (2018). Mediterranean diet and cardiovascular disease prevention: what do we know?. Progress in cardiovascular diseases, 61(1), 62-67.
  11. Tuso, P. J., Ismail, M. H., Ha, B. P., & Bartolotto, C. (2013). Nutritional update for physicians: plant-based diets. The Permanente Journal, 17(2), 61.
  12. UPMC MyHealth Matters (nd). Is intermittent fasting healthy? Retrieved from: