Researchers studied nearly 4,600 women who had gestational diabetes during pregnancy to see if eating a special diet called the Planetary Health Diet could help them stay healthy. Over 30 years, women who followed this diet most closely had a 63% lower chance of having a heart attack compared to those who followed it least. The diet also helped women keep their weight stable and reduced their risk of developing type 2 diabetes. This matters because women who had gestational diabetes face higher risks of serious health problems later in life, and this research shows that what they eat can make a real difference.

The Quick Take

  • What they studied: Whether eating a plant-based diet that’s good for both human health and the environment could help women who had gestational diabetes (a type of diabetes during pregnancy) avoid heart disease and type 2 diabetes later in life.
  • Who participated: 4,633 women who had gestational diabetes during pregnancy, followed for 30 years starting in 1991. The women were nurses, averaging 39 years old when the study began.
  • Key finding: Women who ate the most according to the Planetary Health Diet had a 63% lower risk of heart attacks compared to those who ate it the least. They also gained less weight over time and had lower rates of type 2 diabetes.
  • What it means for you: If you had gestational diabetes, eating more plant-based foods and fewer animal products may significantly lower your chances of heart disease and type 2 diabetes. However, this research shows what happened in one group of nurses, so talk to your doctor about whether this diet is right for your situation.

The Research Details

This was a long-term follow-up study using data from the Nurses’ Health Study II, which has tracked the health of thousands of women since 1989. Researchers looked at women who had gestational diabetes and followed them from 1991 to 2021—a full 30 years. Every 4 years, the women filled out detailed questionnaires about what they ate, and researchers used this information to score how well each woman followed the Planetary Health Diet. The diet emphasizes plant-based foods like vegetables, fruits, whole grains, and nuts while limiting red meat, processed foods, and dairy.

Researchers tracked which women developed heart disease (including heart attacks and strokes) and type 2 diabetes during the study period. They used statistical methods to compare women who followed the diet most closely with those who followed it least closely, while accounting for other factors that affect health like age, smoking, exercise, and body weight.

The study also looked at how changes in diet related to weight changes over 4-year periods. This helped researchers understand whether the diet’s benefits came mainly from weight loss or from other aspects of eating healthier.

This research approach is important because it follows real people over many years in their actual lives, rather than just testing people in a lab. This gives us a better picture of how diet affects health over the long term. The study is particularly valuable because it focuses on women with gestational diabetes, a group known to be at high risk for serious health problems, and it measures actual disease outcomes rather than just blood test results.

This study has several strengths: it followed a large group of women for 30 years, it measured diet multiple times rather than just once, and it tracked actual disease cases rather than just risk factors. The participants were all nurses, which means they likely had good access to healthcare and accurate medical records. However, the study only included nurses, who may be healthier or more health-conscious than the general population, so results might not apply equally to all women. The study shows associations between diet and disease, but cannot prove that the diet directly caused the lower disease risk, since people who eat healthier may also exercise more or have other healthy habits.

What the Results Show

During the 30-year study, 1,053 women developed type 2 diabetes and 90 women had heart disease events (38 heart attacks and 52 strokes). Women who followed the Planetary Health Diet most closely had significantly better outcomes. Most strikingly, women in the highest group for diet adherence had a 63% lower risk of heart attacks compared to those in the lowest group. This means that instead of having a certain number of heart attacks in the lowest group, the highest group had only about one-third as many.

The diet was also associated with lower overall heart disease risk and lower type 2 diabetes risk. However, when researchers dug deeper, they found that much of the benefit came from weight management. About 80% of the diet’s protective effect against type 2 diabetes appeared to work through helping women maintain a healthier weight. For heart disease, weight management accounted for about 15% of the benefit, suggesting the diet helps the heart in other ways beyond just weight control.

When researchers looked at weight changes over 4-year periods, they found a clear pattern: women whose diet adherence decreased the most gained the most weight, averaging 2.3 kilograms (about 5 pounds) over 4 years. In contrast, women who maintained or improved their diet adherence had much smaller weight gains. This suggests the diet helps people naturally maintain a healthier weight without extreme dieting.

The study found that the relationship between diet quality and disease risk was consistent across different groups of women, suggesting the benefits apply broadly. The protective effect against heart disease remained strong even after accounting for other factors like exercise, smoking, and family history. The weight management benefits were particularly notable because they occurred naturally through dietary changes rather than requiring intensive weight loss programs.

Previous research has shown that plant-based diets are good for heart health in general populations, but this is one of the first studies to specifically examine the Planetary Health Diet in women with a history of gestational diabetes. The findings align with other research showing that plant-based eating patterns reduce heart disease and diabetes risk, but this study adds important evidence that these benefits extend to this high-risk group. The study also confirms what other research has suggested: that weight management is a key mechanism through which diet improvements protect heart health.

The study participants were all nurses, who tend to be more health-conscious and have better healthcare access than the general population, so results may not apply equally to all women. The study measured diet through questionnaires every 4 years, which may not capture all dietary changes. Because this is an observational study, we cannot be certain the diet directly caused the health improvements—women who eat healthier may also exercise more or have other healthy habits. The study did not include detailed information about how strictly women followed the diet or whether they received counseling about nutrition. Additionally, the relatively small number of heart disease cases (90 total) means some of the findings have wider ranges of uncertainty.

The Bottom Line

If you had gestational diabetes, consider eating more plant-based foods including vegetables, fruits, whole grains, legumes, and nuts, while reducing red meat, processed foods, and dairy products. This dietary pattern appears to significantly reduce your risk of heart disease and type 2 diabetes. Focus particularly on maintaining a healthy weight, as this is a major way the diet protects your health. Discuss this dietary approach with your doctor or a registered dietitian to make sure it’s appropriate for your individual health situation. Confidence level: Moderate to High for heart disease prevention, Moderate for type 2 diabetes prevention.

This research is most relevant for women who had gestational diabetes during pregnancy, as they are at elevated risk for heart disease and type 2 diabetes. The findings may also apply to women at high risk for type 2 diabetes or heart disease more generally. Women who are pregnant or planning pregnancy should consult their healthcare provider before making major dietary changes. The study was conducted in women, so while the diet may benefit men as well, this specific research doesn’t address that question.

Weight management benefits may appear within 4 years based on this study’s findings. However, protection against heart disease and type 2 diabetes likely develops over many years of consistent healthy eating. You should not expect immediate results, but rather view this as a long-term investment in your health. Some people may notice improved energy, better blood sugar control, or easier weight management within weeks to months of dietary changes.

Want to Apply This Research?

  • Track your adherence to the Planetary Health Diet by logging meals weekly and scoring them based on plant-based food content (vegetables, fruits, whole grains, legumes, nuts) versus animal products and processed foods. Set a goal to increase plant-based foods by 10-20% each month.
  • Use the app to set a specific, achievable goal like ’eat plant-based meals 4 days per week’ or ‘add one serving of vegetables to each meal.’ Start with one meal per day and gradually expand. Use the app’s reminder feature to prompt you to plan meals with plant-based options.
  • Track weight monthly rather than weekly to see the natural weight management benefits of dietary changes. Also monitor energy levels, blood sugar readings (if applicable), and how you feel. Review your diet adherence score every 4 weeks and celebrate improvements. If you have access to blood work, track cholesterol and blood sugar levels annually with your doctor.

This research shows an association between following the Planetary Health Diet and lower disease risk in women with a history of gestational diabetes, but does not prove the diet directly causes these benefits. Individual results may vary based on genetics, overall lifestyle, and other health factors. Before making significant dietary changes, especially if you have gestational diabetes, type 2 diabetes, heart disease, or are pregnant or breastfeeding, consult with your healthcare provider or a registered dietitian. This information is for educational purposes and should not replace professional medical advice. If you experience chest pain, shortness of breath, or other warning signs of heart disease, seek immediate medical attention.