The Ornish Diet: Can It Improve Health and Aid Weight Loss?

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Healthline Diet Score: 4.08 out of 5

The Ornish Diet is a popular diet plan that promises to help reverse chronic disease and enhance health.

It involves making comprehensive lifestyle changes and following a low-fat, plant-based diet filled with fruits, veggies, whole grains, and legumes.

However, it also restricts several healthy food groups and may increase your risk of nutritional deficiencies without proper planning.

This article reviews the Ornish Diet, including whether it improves health and aids weight loss.

DIET REVIEW SCORECARD
  • Overall score: 4.08
  • Weight loss: 5
  • Healthy eating: 4
  • Sustainability: 4.5
  • Whole body health: 3.5
  • Nutrition quality: 4
  • Evidence based: 3.5

BOTTOM LINE: The Ornish diet is a low fat, lacto-ovo-vegetarian diet that focuses on switching up your eating pattern. Though it may help support weight loss, it’s very low in fat and limits intake of specific food groups, which may cause some nutrient deficiencies.

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What is the Ornish Diet?

The Ornish Diet is a plan developed by Dr. Dean Ornish, a physician, researcher, and founder of the Preventive Medicine Research Institute in Sausalito, California.

The plan is essentially a low-fat, lacto-ovo-vegetarian diet that focuses on plant-based ingredients like fruits, veggies, whole grains, and legumes.

Other foods are also permitted on the plan, including soy products, egg whites, and limited amounts of non-fat dairy.

According to the diet’s creator, simply switching up your eating pattern can promote weight loss and reverse the progression of chronic conditions like prostate cancer, heart disease, and diabetes.

It’s said to work by activating health-promoting genes while reversing aging at a cellular level.

Summary

The Ornish Diet is a low-fat, lacto-ovo-vegetarian diet that is said to increase weight loss and reverse disease progression.

How to follow the Ornish Diet

Unlike many other fad diets, the Ornish Diet is straightforward and easy to follow.

There is no need to count calories or track your nutrient intake, and no foods are completely off-limits as part of the diet, aside from most animal products.

However, meat, fish, and poultry are not included in the diet, and high-fat foods like nuts, seeds, and vegetable oils are permitted only in limited amounts.

Fruits, vegetables, whole grains, legumes, and soy foods are key components of the Ornish Diet and should comprise the majority of your meals.

Egg whites are also permitted, and up to two daily servings of non-fat dairy products like milk and yogurt can be enjoyed as well.

Healthy fats should make up about 10% of your total daily calorie intake and mostly come from naturally occurring fats in whole foods like whole grains and legumes.

Three or fewer servings of foods like nuts and seeds can also be eaten per day. However, it’s important to keep in mind that the serving sizes are very small, and one serving should contain fewer than 3 grams of fat.

Also, caffeinated beverages, refined carbs, sugar, alcohol, and low-fat packaged foods should be limited as part of the diet.

In addition to making changes to your diet, it’s also recommended to get at least 30 minutes of moderate exercise daily to optimize results.

Summary

The Ornish Diet involves eating mostly low-fat, plant-based foods and limiting animal products, refined carbs, high-fat foods, and processed ingredients.

Benefits

The Ornish Diet may be associated with several health benefits.

May aid weight loss

The Ornish Diet emphasizes nutrient-dense ingredients like fruits, veggies, and plant-based proteins, making it an excellent option if you’re looking to lose weight.

According to one study in 20 people, following the Ornish Diet for 1 year resulted in an average weight loss of 7.5 pounds (3.3 kg), which was greater than other popular diets like Atkins, Weight Watchers, and the Zone Diet (1).

Similarly, another 1-year study found that 76 participants who followed the Ornish Diet lost an average of 5 pounds (2.2 kg) (2).

Furthermore, other studies show that switching to a vegetarian diet could aid weight loss.

In one study in 74 people with type 2 diabetes, following a vegetarian diet for 6 months was significantly more effective than a low-calorie diet at promoting fat loss (3).

Aids disease prevention

Promising research suggests that the Ornish Diet could help prevent chronic disease.

In fact, studies show that vegetarian diets may be associated with a lower risk of heart disease, diabetes, and obesity (4, 5, 6).

Other studies have found that vegetarian and vegan diets may be linked to a lower risk of certain types of cancer, including stomach, colorectal, prostate, and breast cancer (7, 8, 9 10).

What’s more, one small study in 18 people compared the effects of three popular diets, including the Ornish Diet, over 4 weeks.

The Ornish Diet reduced levels of total cholesterol, triglycerides, LDL (bad) cholesterol, and inflammation, all of which are risk factors for heart disease (11).

Flexible and easy to follow

Unlike other diet plans that require you to carefully count calories or track your nutrient intake, the Ornish Diet requires minimal effort and is relatively easy to follow.

According to the diet’s creator, aside from certain animal products, no foods are completely off-limits on the plan — though some ingredients should be limited.

Even certain prepackaged convenience items like veggie burgers or whole-grain cereals are permitted in moderation, provided they contain fewer than 3 grams of fat per serving.

Given that the diet is not overloaded with complicated rules and regulations, it’s easy to stick to in the long run.

Summary

The Ornish Diet may increase weight loss and aid disease prevention. It’s also more flexible and easier to follow than other diet plans.

Potential downsides

Though the Ornish Diet is associated with several potential benefits, there are some downsides to consider.

For starters, it’s very low in healthy fats, with less than 10% of total daily calories coming from fat.

Most health experts and regulatory agencies recommend getting around 20–35% of your total daily calories from fat to help optimize health (12).

Healthy fats like mono- and polyunsaturated fatty acids can protect against heart disease, reduce inflammation, support brain function, and ensure healthy growth and development (12, 13, 14).

Additionally, it’s important to keep in mind that removing meat and certain animal products from your diet can increase your risk of nutritional deficiencies.

In fact, studies show that vegetarian diets tend to be lower in important nutrients like protein, calcium, vitamin B12, and zinc (15).

Monitoring your intake of these key vitamins and minerals and enjoying a variety of nutrient-dense fruits, veggies, whole grains, and legumes can ensure that you’re able to meet your needs while following the Ornish Diet.

You may also opt to take a multivitamin, which can help fill any gaps in your diet to prevent a nutritional deficiency.

Summary

The Ornish Diet is very low in healthy fats and requires careful planning to prevent nutritional deficiencies.

Foods to eat and avoid

The Ornish Diet is a lacto-ovo-vegetarian diet that encourages a variety of whole foods, including fruits, vegetables, and legumes.

Foods to eat

Here are some foods that you can enjoy as part of the Ornish Diet:

  • Fruits: apples, bananas, oranges, kiwi, grapefruit, berries, pomegranate, melons, pears, apricots
  • Vegetables: broccoli, cauliflower, kale, cabbage, peppers, garlic, onions, spinach, zucchini
  • Legumes: kidney beans, chickpeas, lentils, black beans, lima beans, pinto beans
  • Whole grains: quinoa, amaranth, buckwheat, barley, farro, brown rice, oats
  • Protein sources: tempeh, tofu, egg whites
  • Herbs and spices: garlic, cumin, turmeric, coriander, cilantro, parsley, cinnamon, nutmeg

Foods to limit

The following foods are also permitted in limited amounts on the diet:

  • Nuts and seeds (3 or fewer small servings per day): walnuts, almonds, cashews, pecans, pumpkin seeds, chia seeds, flax seeds
  • Low-fat packaged foods: whole-grain cereals, whole-grain crackers, veggie burgers
  • Caffeinated beverages: up to one cup of coffee or two cups of black tea/decaf coffee per day
  • Dairy products (2 or fewer servings per day): non-fat yogurt, skim milk
  • Fats: olive oil, avocados, coconut oil, butter, vegetable oil, canola oil, olives
  • Refined carbs (2 or fewer servings per day): white pasta, crackers, biscuits, white bread, pancakes, flour tortillas, white rice, honey, agave, brown sugar, white sugar
  • Alcohol (up to 1 serving per day): wine, beer, liquor
  • Processed foods: high-fat convenience meals, baked goods, fast food, potato chips, pretzels

Foods to avoid

Here are some of the foods to avoid on the diet plan:

  • Meat: beef, lamb, goat, veal
  • Seafood: salmon, mackerel, tuna, anchovies, sardines, shrimp, lobster
  • Poultry: chicken, turkey, goose, duck
  • Egg yolks
Summary

Fruits, veggies, legumes, whole grains, and plant-based protein sources are encouraged on the Ornish Diet. Meat, fish, and poultry are prohibited, while high-fat ingredients, refined carbs, and processed foods should be limited.

Sample menu

Here’s a sample 3-day menu for the Ornish Diet.

Day 1

  • Breakfast: tofu scramble with tomatoes, onions, garlic, and peppers
  • Lunch: brown rice with black beans and steamed broccoli
  • Dinner: lentil veggie stew with roasted Brussels sprouts

Day 2

  • Breakfast: egg white omelet with mixed veggies
  • Lunch: bell peppers stuffed with beans, bulgur, tomatoes, onions, kale, and spinach
  • Dinner: chickpea curry with couscous and a side salad

Day 3

  • Breakfast: oatmeal with strawberries, blueberries, and cinnamon
  • Lunch: zucchini noodles with pesto and cannellini bean meatballs
  • Dinner: teriyaki tempeh with quinoa and stir-fried veggies
Summary

The menu above provides some meal ideas that can be included on the Ornish Diet.

The bottom line

The Ornish Diet is a low-fat, lacto-ovo-vegetarian diet that claims to offer substantial health benefits.

In addition to being flexible and easy to follow, some studies suggest that the Ornish Diet may help increase weight loss and protect against chronic disease.

However, it’s also very low in healthy fats and may lack certain vitamins and minerals, which can increase your risk of nutritional deficiencies.

Thus, if you want to give the Ornish Diet a try, be sure to plan it carefully to avoid negative health effects.