Ornish Diet Guide: Benefits, Drawbacks + What You Can Eat

I first learned about the Ornish Diet plan when I was getting my Masters degree in Exercise Science and Nutrition back in 2010.

At that time, I was doing a thesis on cardiovascular disease interventions, and the Ornish Diet plan was consistently coming up as a recommended diet for heart health. 

But what is the Ornish Diet plan, and is it good for weight loss? Is the Ornish Diet actually the best diet for preventing cardiovascular disease?

In this diet guide, we will discuss what the Ornish Diet plan involves, the principles of its meal plan, foods to eat and foods to avoid, and potential Ornish Diet health benefits and drawbacks.

Lets jump in!

What Is the Ornish Diet Plan?

The Ornish Diet was developed by Dr. Dean Ornish, MD, with the purpose of being a healthy diet to promote heart health.

The defining characteristic of Dr. Dean Ornish’s program is that it is a very low-fat diet, restricting daily fat intake to less than 10% of your total calories per day. 

Moreover, all fat must come from plant-based foods rather than animal products.

Therefore, the Ornish Diet plan is a plant-based or vegetarian diet because Dr. Ornish thought that animal-based foods increase the risk of cardiovascular disease and plaque formation in the arteries.

Rather than necessarily being a weight loss diet, the primary purpose of the Ornish Diet plan is to help prevent the progression of coronary artery disease (CAD) and reverse the formation of atherosclerotic plaques in the coronary arteries.

You do not have to count calories or servings on the Ornish Diet. 

Instead, the primary emphasis is on minimizing fat intake, so you do need to keep track of how much fat you consume and make deliberate food choices to eat fat-free options (skim milk vs reduced fat milk, egg whites vs whole eggs, etc.).

The Ornish Diet diet foods are primarily low in cholesterol, fat, and refined carbs, all of which may help prevent heart disease.

It falls under the category of plant-based diets, which center around eating plant foods rather than animal-based foods (meat, poultry, eggs, dairy, fish, seafood, etc.). It is basically a subtype of the ovo-lacto vegetarian diet.

When comparing the Ornish Diet vs. a vegetarian diet, it can be said that the Engine 2 diet food list is even stricter since it also puts stipulations on all plant-based foods, and eggs and milk are low-fat.

What You Can Eat On the Ornish Diet Meal Plan?

There is no specific Ornish Diet plan. Rather, there is a spectrum in terms of how to follow it based on your relative risk for coronary artery disease versus your current affliction with the condition.

On one end of the spectrum is the Ornish Diet reversal food plan. 

This is used for people who have already been diagnosed with atherosclerosis and are trying to reverse heart disease and restore health to the arteries. Ornish’s Program For Reversing Heart Disease is a very low-fat vegetarian meal plan.

On the other end of the spectrum, there is a less restrictive Ornish Diet prevention meal plan.

Here, the goal is to prevent coronary artery disease by following a low-fat eating plan, but the restrictions are not as intense as the Ornish Diet CAD reversal program.

For example, you can have some lean animal proteins, such as fish and chicken breast, along with a few more healthy fats, such as nuts, seeds, and avocados.

On any version of the Ornish Diet plan for heart disease, you cannot have processed foods that are high-fat, such as breaded products, fried foods, chips, or even refined grains.

No animal products with fat are permitted on the Ornish Diet heart disease reversal food list. This includes any meat, poultry, seafood, butter, egg yolks, and full-fat dairy.

Because fats are limited, any food high in fat, even if healthy, will naturally need to be restricted because fats are high in calories, and you can only consume up to 10% of your total caloric intake from fats on the Ornish Diet.

Is the Ornish Diet Good for Weight Loss and Health?

The Ornish Diet was initially designed to reduce the risk of coronary artery disease, not necessarily to promote weight loss.

This isnt to say that you cant follow the Ornish Diet for weight loss or that the Ornish Diet plan isnt good for weight loss, but that is not the goal or purpose of the diet, rather it is to improve heart health and reduce the risk of coronary artery disease.¹Dansinger, M. L., Gleason, J. A., Griffith, J. L., Selker, H. P., & Schaefer, E. J. (2005). Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction. JAMA, 293(1), 43. https://doi.org/10.1001/jama.293.1.43

Any diet can support weight loss if you are in a caloric deficit.²Weight Loss Depends on Less Calories, Not Nutrient Mix. (2015, May 22). National Institutes of Health (NIH). https://www.nih.gov/news-events/nih-research-matters/weight-loss-depends-less-calories-not-nutrient-mix

To this end, even if you are trying to maintain your weight or perhaps you want to gain weight, you can still follow the Ornish Diet by adjusting your caloric intake accordingly.

That said, you may lose weight on the Ornish Diet if that is your goal or perhaps even without necessarily trying. 

The foods that are emphasized have a low caloric density, especially veggies, fruits, lean proteins like egg whites, and other whole, natural, unprocessed foods rather than packaged foods, foods with added sugars, or ultra-refined foods.

This can help you feel full on fewer calories,³Buckland, N. J., Camidge, D., Croden, F., Lavin, J. H., Stubbs, R. J., Hetherington, M. M., Blundell, J. E., & Finlayson, G. (2018). A Low EnergyDense Diet in the Context of a Weight-Management Program Affects Appetite Control in Overweight and Obese Women. The Journal of Nutrition, 148(5), 798806. https://doi.org/10.1093/jn/nxy041 and indeed numerous studies have found that plant-based diets⁴Huang, R.-Y., Huang, C.-C., Hu, F. B., & Chavarro, J. E. (2016). Vegetarian Diets and Weight Reduction: a Meta-Analysis of Randomized Controlled Trials. Journal of General Internal Medicine, 31(1), 109116. https://doi.org/10.1007/s11606-015-3390-7 as well as those that prioritize low energy density foods⁵Vadiveloo, M., Parker, H., & Raynor, H. (2017). Increasing low-energy-dense foods and decreasing high-energy-dense foods differently influence weight loss trial outcomes. International Journal of Obesity, 42(3), 479486. https://doi.org/10.1038/ijo.2017.303 tend to be supportive of weight loss.⁶Rouhani, M. H., Haghighatdoost, F., Surkan, P. J., & Azadbakht, L. (2016). Associations between dietary energy density and obesity: A systematic review and meta-analysis of observational studies. Nutrition, 32(10), 10371047. https://doi.org/10.1016/j.nut.2016.03.017

The Ornish Diet plan can be helpful for some people and has been shown to improve cardiovascular disease risk factors in older studies in which the diet was implemented as an intervention.⁷Ludwig, D. S., Willett, W. C., Volek, J. S., & Neuhouser, M. L. (2018). Dietary fat: From foe to friend? Science, 362(6416), 764770. https://doi.org/10.1126/science.aau2096

However, numerous studies since that time have found that there is not necessarily a cardiovascular benefit from restricting dietary fat intake to less than 25% of your total daily calories.⁸Ebbeling, C. B., Young, I. S., Lichtenstein, A. H., Ludwig, D. S., McKinley, M., Perez-Escamilla, R., & Rimm, E. (2017). Dietary Fat: Friend or Foe? Clinical Chemistry, 64(1), 3441. https://doi.org/10.1373/clinchem.2017.274084

This is particularly true when the fats are coming from healthy food sources rather than saturated fat or trans fats.⁹American Heart Association. (2021, November 1). Saturated Fat. American Heart Association. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/saturated-fats

To this end, although the American Heart Association used to recommend following a low-fat diet for heart health, these guidelines have since changed.¹⁰American Heart Association. (2021, November 1). The American Heart Associations Diet and Lifestyle Recommendations. Www.heart.org. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/nutrition-basics/aha-diet-and-lifestyle-recommendations

Again, this isnt to say that the Ornish Diet cant be a good way to reduce your risk of heart disease, but the extremely low fat intake may be unnecessarily restrictive.¹¹Karam, G., Agarwal, A., Sadeghirad, B., Jalink, M., Hitchcock, C. L., Ge, L., Kiflen, R., Ahmed, W., Zea, A. M., Milenkovic, J., Chedrawe, M. A., Rabassa, M., Dib, R. E., Goldenberg, J. Z., Guyatt, G. H., Boyce, E., & Johnston, B. C. (2023). Comparison of seven popular structured dietary programmes and risk of mortality and major cardiovascular events in patients at increased cardiovascular risk: systematic review and network meta-analysis. BMJ, 380, e072003. https://doi.org/10.1136/bmj-2022-072003

Not only does it make adhering to the diet in the long-term difficult because the daily fat allowance is so low, but it can also be potentially problematic.

Healthy fats such as olive oil are important for numerous functions in the body, one of which is helping absorb fat soluble vitamins such as vitamins A, D, E, and K.¹²Liu, A. G., Ford, N. A., Hu, F. B., Zelman, K. M., Mozaffarian, D., & Kris-Etherton, P. M. (2017). A healthy approach to dietary fats: understanding the science and taking action to reduce consumer confusion. Nutrition Journal, 16(1). https://doi.org/10.1186/s12937-017-0271-4

Fats are also necessary for forming healthy cell membranes, producing hormones, among other benefits.

Therefore, long-term adherence to the very low-fat Ornish Diet plan may result in some nutritional deficiencies and other physiological sequelae of insufficient fat consumption where just adding supplements may not be the best solution.

Overall, the Ornish Diet plan is not as popular as it used to be, given our greater understanding of the dietary risk factors that affect coronary artery disease and those that dont.

This diet plan is much lower in fat than seems necessary, which may end up being more deleterious to your health than any possible potential risk reduction related to coronary heart disease.

If you want to try the Ornish Diet plan for weight loss and core heart health, you should speak with your healthcare provider or work with a nutritionist or registered dietitian to ensure it’s safe to keep your dietary fat intake so low.