Researchers studied 260 breast cancer survivors who were overweight to see if changing their diet and exercise habits could help them lose weight. Over two years, some participants received help with diet changes, some with exercise, some with both, and some with minimal support. The study found that people who got diet help or diet plus exercise help made bigger improvements in their eating patterns compared to those with minimal support. Everyone in the study improved their Mediterranean diet habits (eating more vegetables and olive oil, less processed foods), but the biggest changes happened in the first six months.

The Quick Take

  • What they studied: Whether helping breast cancer survivors change their diet and/or exercise habits could improve their eating patterns and help them lose weight over two years
  • Who participated: 260 breast cancer survivors who were overweight or obese (BMI of 25 or higher), divided into four groups receiving different levels of diet and exercise support
  • Key finding: People who received diet help or diet plus exercise help made bigger improvements in their eating patterns than those with minimal support. Everyone improved their Mediterranean diet habits, eating more vegetables and olive oil while cutting back on processed foods and sweets.
  • What it means for you: If you’re a breast cancer survivor struggling with weight, getting personalized help with diet changes—especially combined with exercise—may help you eat healthier and lose weight. The biggest improvements happened in the first six months, suggesting that’s when focused effort pays off most.

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of research. Researchers randomly assigned 260 breast cancer survivors into four different groups. One group got help with diet changes, one got help with exercise, one got help with both diet and exercise, and one got minimal support (the comparison group). All participants were followed for two years, and researchers tracked what they ate using detailed food questionnaires at the start, and then at regular check-ins throughout the study.

The researchers used special statistical methods to identify three main eating patterns at the beginning of the study: a Mediterranean pattern (lots of vegetables and olive oil), a sweet pattern (cakes and candy), and a Western pattern (red meat and processed foods). They then tracked how these patterns changed over time in each group.

This approach is important because it looks at real eating patterns rather than just counting calories. It helps researchers understand how people actually change their food choices, not just whether they eat less overall.

This study design is strong because randomly assigning people to different groups helps researchers figure out what actually causes the changes, not just what happens by chance. Following people for two years shows whether changes stick around long-term, which is more useful than short-term studies. By looking at eating patterns rather than just individual foods, researchers can understand the bigger picture of how people’s diets change.

This is a well-designed study published in a peer-reviewed medical journal. The researchers used validated questionnaires (tools that have been tested and proven accurate) to measure what people ate. The study included a comparison group with minimal intervention, which helps show that the improvements came from the program, not just from being in a study. The large sample size of 260 participants makes the results more reliable. However, this is a secondary analysis, meaning researchers looked at diet data from a larger study focused on weight loss, so some details about how the original study was conducted would be important to know.

What the Results Show

The study found that breast cancer survivors who received diet help or diet plus exercise help made bigger improvements in their eating patterns compared to those with minimal support. Specifically, people in these intervention groups reduced their consumption of foods that made up their baseline eating patterns—meaning they ate less of the unhealthy foods they typically ate before the program.

Everyone in the study improved their adherence to the Mediterranean diet, which emphasizes vegetables, olive oil, and whole grains while limiting processed foods. This improvement happened across all four groups, but was most pronounced in those who received active intervention. The biggest changes in what people ate happened during the first six months of the program, suggesting that’s when people are most motivated and making the most significant shifts in their eating habits.

The study also found that people who were 60 years or older made bigger improvements than younger participants. This is interesting because it suggests that older breast cancer survivors may be particularly responsive to diet intervention programs. Overall, participants significantly reduced their energy intake (calories) and nutrient intake, particularly in the first six months, indicating they were eating less overall while also making healthier food choices.

The research showed that the Mediterranean diet improvements happened in all groups, even those with minimal intervention. This suggests that simply being part of a study about healthy eating may help people make better food choices. However, the groups that received active diet help made more substantial changes. The study also identified that reducing specific food groups—like sweets, processed meats, and red meat—was a key way that participants improved their diets. These secondary findings suggest that targeted education about specific foods to reduce may be particularly effective.

This study builds on previous research showing that lifestyle interventions can help people lose weight and eat healthier. However, it provides new insights by showing exactly how eating patterns change over time and which groups benefit most. The finding that Mediterranean diet improvements happened across all groups aligns with other research showing this diet pattern is beneficial for cancer survivors. The study adds to growing evidence that personalized interventions combining diet and exercise may be more effective than either approach alone.

This study has some important limitations to consider. First, it’s a secondary analysis, meaning researchers looked at diet data from a study primarily designed to measure weight loss, so some details about the original study design matter. Second, the study relied on people self-reporting what they ate using questionnaires, which can be less accurate than other methods. Third, we don’t know if the improvements in eating patterns actually led to weight loss or other health benefits—the study focused on diet changes, not health outcomes. Fourth, the study included breast cancer survivors who volunteered for a lifestyle program, so results may not apply to all breast cancer survivors. Finally, the study doesn’t tell us how long these dietary improvements lasted after the program ended.

The Bottom Line

If you’re a breast cancer survivor who is overweight or obese, consider seeking personalized help with diet changes, ideally combined with increased physical activity. The evidence suggests this approach can help you make meaningful improvements in your eating patterns. Focus your efforts in the first six months, as that’s when the biggest changes tend to happen. Aim to adopt a Mediterranean-style diet with more vegetables, olive oil, and whole grains while reducing processed foods, sweets, and red meat. These recommendations are supported by moderate evidence from this well-designed study, though individual results will vary.

These findings are most relevant to breast cancer survivors who are overweight or obese and want to improve their diet. They may be particularly helpful for survivors age 60 and older, who showed the most improvement in this study. The findings also matter for healthcare providers, nutritionists, and cancer support programs designing interventions for survivors. However, if you’re a breast cancer survivor at a healthy weight or with different health conditions, you should talk with your doctor about whether these recommendations apply to you. The study focused on survivors in a structured program, so results may differ for those trying to make changes on their own.

Based on this study, expect to see the biggest changes in your eating patterns within the first six months of making dietary changes. This is when most participants in the study made their most significant improvements. However, maintaining these changes over the long term requires ongoing effort. The study followed people for two years, and improvements were sustained throughout that period, suggesting that with continued commitment, you can maintain better eating habits for years.

Want to Apply This Research?

  • Track your daily intake of three key food groups: (1) vegetables and olive oil, (2) processed meats and red meat, and (3) sweets and cakes. Use a simple 1-10 scale to rate how well you followed Mediterranean diet principles each day. This mirrors the three eating patterns identified in the study and gives you specific, measurable targets.
  • Set a specific goal to add one Mediterranean diet element each week (like cooking with olive oil, adding an extra vegetable serving, or replacing one processed food with a whole food alternative) while removing one unhealthy element. Track these changes in the app and celebrate weekly wins. The study showed the first six months are critical, so focus your app notifications and reminders during this period.
  • Use the app to track your eating pattern changes monthly rather than daily, since the study measured changes over months and years, not days. Create a simple Mediterranean diet adherence score based on your weekly tracking. Set monthly check-ins to review progress and adjust your goals. Since the study showed sustained improvements over two years, plan for long-term tracking with quarterly reviews to maintain motivation and identify any backsliding.

This study provides evidence that dietary interventions can help breast cancer survivors improve their eating patterns, but it is not a substitute for personalized medical advice. If you are a breast cancer survivor considering dietary changes, especially if you have other health conditions or take medications, please consult with your oncologist, primary care doctor, or a registered dietitian before making significant changes to your diet or exercise routine. Individual results vary, and what works for one person may not work for another. This research focused on changes in eating patterns, not on specific health outcomes like weight loss or disease recurrence, so you should discuss your specific health goals with your healthcare team.