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Study: A low-fat diet may decrease postmenopausal breast cancer deaths

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This study is about:

how a balanced, low-fat diet significantly lowers the risk of dying from breast cancer in postmenopausal women.

Why is this study important?

This trial is the first to show that a healthy diet can reduce the risk of death from breast cancer.

Study findings:

In 1993, the Women’s Health Initiative Diet Modification Trial looked at almost 50,000 postmenopausal women with no history of breast cancer. Participants were women of multiple races, ethnicities and varying ages. They were to one of two diets.

1. Women in the usual-diet group got about 30 percent (1/3) of their daily calories from fat.

  • This group had one follow-up visit per year.

2. Women in the low-fat diet group were asked to reduce their fat intake to 20 percent (1/5) of daily calories. 

  • They were also encouraged to eat more vegetables, fruits and whole grains.
    • 5 servings of vegetables and fruits every day.
    • 6 servings of whole grains every day.
  • This group also had 18 small-group support sessions and quarterly follow-up.

Women in the low-fat diet group stuck to the diet for about 8½ years. Most of them increased their intake of fruits, vegetables and whole grains and cut their daily fat intake to 25 percent or less, although most did not reach the 20 percent goal. Women in this trial were followed for 20 years. During that time, over 3,000 (15 percent) women developed breast cancer.

Compared to women in the usual-diet group, women in the low-fat diet group had:

  • a 21 percent lower risk of death from breast cancer.
  • a 15 percent lower risk of death from any cause.

Women with additional risk factors—a waist circumference greater than 35 inches (88 cm), high blood pressure or taking drugs to reduce blood pressure, elevated cholesterol, or a history of diabetes—had greater benefit from a low-fat diet.

Women with three or four risk factors who followed the low-fat diet decreased their risk for death from breast cancer by almost 70 percent.

What does this mean for me?

It is important to understand that a low-fat diet did not significantly reduce the risk of developing breast cancer.  However, for postmenopausal women, a low-fat diet significantly reduced the risk of dying from breast cancer or other causes. It also dramatically reduced the risk of breast cancer-related death for women who had other health risk factors.

This study did not look at how a low-fat diet affects the risk of dying from breast cancer among:

  • premenopausal women
  • women who are at high risk for breast cancer

Therefore, it is unclear if a low-fat diet would have the same protective effects in these women.

You may have different nutritional needs if you are pregnant, nursing or in treatment; it is important to discuss these requirements with your doctor.


Most women in the low-fat diet group were unable to achieve the recommended reduction of fat in their diets and fell short of the targeted number of whole-grain servings.  The degree to which women stuck to the diet relied primarily on self-reported eating habits.  Finally, given the 20-year follow-up period, differences other than diet may have existed between the two groups.


A reduction in dietary fat and an increase in fruits, vegetables and whole grains can result in important health outcomes.  It can lower the risk of death from breast cancer by 21 percent and reduce the risk of death from any cause by 15 percent. Importantly, for women with other risk factors it can decrease risk of death from breast cancer by almost 70 percent.

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(Posted 6/13/19)


Prentice RL, Aragaki AK, Howard BV, Chlebowski RT, Thomson CA, Van Horn L, Tinker LF, Manson JE, Anderson GL, Kuller LE, Neuhouser ML, Johnson KC, Snetselaar L, Rossouw JE. Low-Fat Dietary Pattern among Postmenopausal Women Influences Long-Term Cancer, Cardiovascular Disease, and Diabetes Outcomes. J Nutr. 2019.


FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

This article is relevant for:

Post-menopausal women with no breast cancer diagnosis

This article is also relevant for:

healthy people with average cancer risk

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Expert Guidelines
Expert Guidelines

The American Cancer Society (ACS) guidelines on exercise, nutrition and weight for cancer prevention recommend the following: 

Diet and nutrition

  • Follow a healthy eating pattern, including:
    • foods that are high in nutrients in amounts that help you acheive and maintain a healthy body weight.
    • a variety of vegetables, fiber-rich legumes (beans and peas) and whole fruits in a variety of colors. Consume at least 2½ to 3 cups of vegetables and 1½ to 2 cups of fruit each day, depending on your calorie requirements. 
    • whole grains rather than refined grains. At least half of the grains you eat should be whole grains. 
  • A healthy eating pattern that limits or does not include:
    • red and processed meats.
    • sugar-sweetened beverages. 
    • highly processed foods and refined grain products.
  • It is best not to drink alcohol. People who choose to drink alcohol should:
    • have no more than 1 drink per day (women) or 2 drinks per day (men).


  • Exercise regularly.
    • Adults should get at least 150 minutes of moderate-intensity activity (equal to a brisk walk) or 75 minutes of vigorous activity (heart rate is increased, breathing is faster and you are sweating) each week, preferably spread throughout the week.
    • Physical activity has been shown to lower the risk of several types of cancer, including breast, endometrial, and colon. It also reduces the risk of other serious diseases including diabetes and heart disease.


  • Achieve and keep a healthy weight.
    • Being overweight or obese is a risk factor for many cancers, including breast, colon, endometrial and pancreatic. You can control your weight through regular exercise and healthy eating.

Other experts, including the following, also provide guidelines for exercise, nutrition and health: 

Updated: 07/19/2022

Questions To Ask Your Doctor
Questions To Ask Your Doctor

  • What is a good, balanced diet for me?
  • What is a healthy body weight given my age, size and health?
  • Can you refer me to a nutritionist?
  • Are there any activities that I should begin or avoid?

Open Clinical Trials
Open Clinical Trials

The following are studies focused on nutrition and cancer prevention. 

Breast cancer

Colorectal cancer

Visit our Featured Research Page and Research Search and Enroll Tool to find additional studies enrolling people with or at high risk for cancer.

Updated: 05/29/2024

Find Experts
Find Experts

The following resources can help you locate a nutritionist near you or via telehealth

Finding nutritionists

  • You can find a registered dietician in your area through, the website for the Academy of Nutrition and Dietetics. Search for nutritionists by specialty, including "cancer," "weight management" and "heart health."

Related experts

  • The Livestrong at the YMCA program includes a free 12-week membership and fitness training with certified exercise experts. You can search by zip code for a program near you.  

Other ways to find experts

  • Register for the FORCE Message Boards and post on the Find a Specialist board to connect with other people who share your situation. 
  • The National Cancer Institute (NCI)-Designated Comprehensive Cancer Centers have specialists to manage the symptoms and side effects of cancer prevention or treatment. 
  • FORCE partners with Savor Health® to provide free, personalized, evidence-based nutrition support 24/7 and “on-demand" through their text-based Intelligent Nutrition Assistant (Ina®). You can subscribe here


Updated: 11/20/2023

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