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Ornish diet


Also listed as: Diet, Ornish
Related terms
Author information
Diet outline

Related Terms
  • Cholesterol, Dean Ornish, diet, heart disease, high cholesterol, high fiber, low fat diet, prevention diet, reversal diet, vegetarian, whole grains.

  • The Ornish diet is a low fat vegetarian way of eating with less than 10% of daily calories from fat (an average of 15 to 25g of fat per day), 70-75% from carbohydrates and 15-20% from protein. This diet encourages consumption of beans, fruits, vegetables, and whole grains and limits intake of processed foods, high-fat dairy products, simple sugars and alcohol.
  • Dr. Dean Ornish, a physician who has directed clinical research for the past 25 years, created this diet as a lifestyle modification to reverse existing heart disease by emphasizing foods that are very low in fat yet filling, such as high-fiber grains and legumes (i.e. beans and peas). In addition to the proposed heart healthy effects of the Ornish diet, patients may also lose weight. Based on Ornish's research, patients lost an average of 25 pounds over the course of a year.
  • Ornish has promoted two varieties of his popular way of eating to address health concerns of different people. The reversal diet is recommended for people with existing heart disease desiring to reduce their risk of suffering a heart attack or other coronary heart disease event. The prevention diet is advocated for otherwise healthy individuals with levels of LDL cholesterol greater than 150mg/dL or those with a ratio of total cholesterol to high-density lipoprotein (HDL or "good" cholesterol) that is less than 3.0.
  • The Ornish diets are completely vegetarian. Cholesterol and saturated fat are excluded; no animal products (except egg whites and nonfat dairy products) are allowed. All nuts, seeds, avocados, chocolate, olives, coconuts and oils are eliminated except a small amount of canola oil for cooking and oil that supplies omega-3 essential fatty acids. The Ornish diet also prohibits caffeine but allows a moderate intake of alcohol and salt. There is no restriction on calorie intake. Several small meals a day rather than three large meals is also recommended.
  • Several studies have compared various diets and their effects on cholesterol levels, heart disease and weight loss. Based on available research, the Ornish diet appears to be more successful in lowering the risk of heart disease than other diets, but has also been noted as one of the most difficult diets to follow because of the required lifestyle changes.

Theory / Evidence
  • The Ornish diet is based on the belief that metabolism was altered when early humans could not depend on regular meals due to the scarcity of regularly available food. The body, to preserve energy, would store any extra energy as fat. People in modern societies generally have unlimited access to food but their bodies have not adapted to this new way of living.
  • Because the rate at which a person burns calories may decrease when a person consumes fewer calories, is it easy to hit a weight loss plateau soon after beginning a new, lower-calorie diet.
  • It is theorized that if individuals eat only when hungry on the Ornish diet, without portion control, that their metabolism will stay the same, or perhaps increase. The high-fiber content also slows down the absorption of food into the digestive system, so a person feels full longer with small portions than if eating calorie-restricted small portions. The complex carbohydrates may help blood sugar remain more stable.
  • The Ornish diet also encourages long, slow exercise that uses body fat as fuel. Moderate exercise done on a regular basis revs up the resting metabolism, while some have suggested that short periods of intense exercise decrease metabolism.
  • Meditation is used as a way of quieting the mind, increasing self-awareness and coping with stress. Various forms of meditation, including mindfulness, transcendental meditation, and "meditation-based stress reduction programs" have been studied for their effects on anxiety and stress. Although benefits have been reported, the available research has not been well designed or reported, and cannot be considered conclusive. Better studies are needed before a recommendation can be made.
  • A study conducted by Ornish for the American Cancer Society claimed that diet and exercise may play an important role in keeping prostate cancer at bay. The same lifestyle changes that help prevent heart disease also appear to keep prostate specific antigen (PSA) levels low, and may even have an impact on how quickly a tumor grows. Ornish and his colleagues studied 93 men with early stage prostate cancer who had decided to pursue watchful waiting rather than active treatment with surgery, radiation or chemotherapy. Men in one group were told to follow their normal lifestyle habits, while those in the other made some big changes. These men went on a strict vegan diet that contained only 10% of calories from fat, (most Americans get 30% or more calories from fat), supplemented with soy, fish oil, selenium and vitamins E and C. They also began regular exercise (30 minutes of walking 6 days a week), doing yoga or some other type of meditation and participating in support groups. After a year, the researchers measured the men's PSA levels. Men who had followed the diet and exercise plan saw their PSA levels decrease by 0.3 ng/mL (about 4%), while those who followed their usual routine saw their PSA levels increase by 0.4 ng/mL (about 6%). The study only measured PSA and other lab results; it did not look at survival or whether the disease had spread. Also, the follow up period was only a year, which may not be long enough to see all potential effects of the different approaches. Because there were so many aspects to the regimen, it is not possible to tell how much of an effect (if any) each individual component (vegan diet, supplements, exercise, stress reduction, support group participation) may have had on the PSA level. The study also could not determine whether making these lifestyle changes would actually prevent prostate cancer in the first place. Ornish, the developer of the diet, also conducted the study, which may be a source of potential bias. In the study, 3 men quit the plan because it they found it to be too difficult.
  • Another study compared the Atkins, Ornish, Weight Watchers and Zone diets for weight loss and heart disease risk reduction. The study set out to assess adherence rates and the effectiveness of the four popular diets for weight loss and cardiac risk factor reduction. A total of 160 participants were randomly assigned to either Atkins (carbohydrate restriction), Zone (macronutrient balance), Weight Watchers (calorie restriction) or Ornish (fat restriction) diet groups. The mean weight loss at one year was: 2.1 (4.8) kg for Atkins (53% participants completed), 3.2 (6.0) kg for Zone (65% completed), 3.0 (4.9) kg for Weight Watchers (65% completed) and 3.3 (7.3) kg for Ornish (50% completed). Greater effects were observed in study completers. Each diet significantly reduced the low-density lipoprotein/high-density lipoprotein (HDL) cholesterol ratio by approximately 10% with no significant effects on blood pressure or glucose at one year. Amount of weight loss was associated with self-reported dietary adherence level but not with diet type. For each diet, decreasing levels of total/HDL cholesterol, C-reactive protein and insulin were significantly associated with weight loss with no significant difference between diets. Each popular diet modestly reduced body weight and several cardiac risk factors at one year. Overall dietary adherence rates were low, although increased adherence was associated with greater weight loss and cardiac risk factor reductions for each diet group.
  • The Lifestyle Heart Trial studied the effects of the Ornish diet. On average, Ornish's patients lost 24 lbs in a year and had a 37% reduction in LDL cholesterol levels (HDL cholesterol levels were unchanged). Additionally, there was a 91% reduction in angina frequency (chest pain) and a significant degree of angiographically measured coronary stenosis regression. It was unclear to what degree other lifestyle modifications such as exercise and stress reduction, which are integral parts of the Ornish program, played in these results. Based upon these favorable findings, the National Institutes of Health is embarking upon a multimillion-dollar study of the Ornish diet vs. bypass surgery in patients with coronary disease.
  • Overall, there are mixed findings about the Ornish diet's efficacy compared with other diets (low carbohydrate, calorie restriction, etc). However, most results seem promising and the Ornish diet and lifestyle modification may be effective in reducing cardiac disease risks and aiding in weight loss.


Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Intensive lifestyle changes may have positive effect on prostate cancer. 11 August 2005. American Cancer Society. 21 June 2006.
  2. Dansinger ML, Gleason JA, Griffith JL et al. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA. 2005 Jan 5;293(1):43-53.
  3. Moyad MA. Fad diets and obesity--Part IV: Low-carbohydrate vs. low-fat diets. Urol Nurs. 2005 Feb;25(1):67-70.
  4. Ornish D. Low fat diets. N Engl J Med. 1998 Jan 8;338(2):127; author reply 128-9.
  5. Rosenthal, Robert L. Effectiveness of altering serum cholesterol levels without drugs. Proc (Bayl Univ Med Cent). 2000 October; 13(4): 351-355.

Diet outline
  • People wishing to follow a version of the Ornish diet should become familiar with reading nutritional labels. Some of the nonfat or very low-fat commercially available products may be high in sugar and should be avoided. Additionally, Ornish suggests eating many smaller, healthy meals to curb hunger that may occur. Using this method, a person may feel full faster and eat more food without increasing the number of calories.
  • Exercise is recommended in the form of at least 30 minutes of moderate activity a day, or an hour three times a week. Using some kind of stress-management technique, such as meditation, massage, psychotherapy, or yoga, is also recommended.
  • Smoking cessation is strongly encouraged as a way to improve cardiovascular health. The program uses a variety of techniques to help participants stop smoking including education about the adverse health effects of smoking and the benefits of quitting and referral to a variety of books and professional resources specializing in smoking cessation.
  • The following are examples of foods that may be eaten as part of the Ornish diet. For a complete listing, consult a qualified healthcare professional or nutritionist.
  • Beans and legumes: Lentils, kidney beans, peas, black beans, red beans, split peas, soybeans, black-eyed peas, garbanzos, navy beans, etc.
  • Fruits: Apples, apricots, bananas, strawberries, cherries, blueberries, oranges, peaches, raspberries, cantaloupes, watermelons, pears, honeydew melons, pineapples, tomatoes, etc.
  • Grains: Corn, rice, oats, wheat, millet, barley, buckwheat, etc.
  • Vegetables: Potatoes, zucchini, broccoli, carrots, lettuce, mushrooms, eggplant, celery, asparagus, onions, sweet potatoes, spinach, etc.
  • The following foods are examples that may be eaten in moderation:
  • Nonfat dairy products: Including skim milk, nonfat yogurt, nonfat cheeses, nonfat sour cream, and egg whites.
  • Nonfat or very low-fat commercially available products: Including whole grain breakfast cereals, Health Valley chili (and many other Health Valley products), Kraft Free nonfat mayonnaise and salad dressings, Guiltless Gourmet tortilla chips, Quaker Oats oatmeal, Nabisco fat-free crackers, Fleishmann's Egg Beaters, Pritikin soups.
  • The Ornish diet recommends that less than 10% of a person's calories be from fat. The following foods are examples that should be avoided:
  • Foods to avoid: Meats (all kinds, including chicken and fish); oils (all kinds) and oil-containing products (including margarines and most salad dressings); avocados, olives, nuts and seeds, high-fat or "low-fat" dairy (including whole milk, yogurt, butter, cheese, egg yolks, cream, etc.); sugar and simple sugar derivatives (honey, molasses, corn syrup, high fructose syrup, etc.); alcohol; and any commercially available products with more than two grams of fat per serving.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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