Scientists are looking at whether the ketogenic diet—a way of eating that’s very low in carbs and high in fat—might help treat diseases beyond epilepsy. This review examined recent research on how keto affects obesity, diabetes, brain diseases like Alzheimer’s, mental health conditions, and cancer. The diet appears to help people control blood sugar and lose weight, and it might help the brain work better in some cases. However, researchers say we need more long-term studies before doctors should recommend keto as a standard treatment for these conditions. Most current studies are too short and don’t follow consistent rules about how people should eat.

The Quick Take

  • What they studied: Whether eating a ketogenic diet (very low carbs, high fat) could help treat various diseases like diabetes, Alzheimer’s disease, depression, and cancer
  • Who participated: This was a review article that looked at many different studies involving thousands of people, but didn’t conduct a new study itself
  • Key finding: The keto diet shows promise for helping people with diabetes and obesity control their blood sugar and lose weight, and may help brain function in some cases, but we don’t have enough solid evidence yet to say it works for treating serious diseases like cancer or mental illness
  • What it means for you: If you have diabetes or obesity, keto might be worth discussing with your doctor, but it shouldn’t replace standard medical treatments. For other conditions, it’s too early to rely on keto as a treatment without more research

The Research Details

This is a review article, which means researchers looked at and summarized findings from many other studies instead of doing their own experiment. They focused on recent clinical evidence about how the ketogenic diet affects different diseases. The ketogenic diet is a way of eating where you eat very few carbohydrates (like bread, pasta, and sugar) and instead eat mostly fats and proteins. This forces your body to burn fat for energy instead of carbs, creating substances called ketones. The researchers examined studies about how this diet affects weight, blood sugar control, brain health, mood, and cancer.

By reviewing many studies together, researchers can see patterns and understand what we actually know versus what we still need to learn. This helps doctors decide whether to recommend new treatments and tells scientists where to focus future research.

This review is published in a respected medical journal, which is good. However, the researchers point out that the individual studies they reviewed had problems: they were often too short, didn’t all follow the same rules about what people should eat, people didn’t always stick to the diet, and people’s bodies responded differently. These issues make it harder to know if the results are reliable.

What the Results Show

For weight and blood sugar control, the keto diet appears to work better than many people expected. It helps people lose weight and improves how well their bodies handle insulin and blood sugar. This happens partly because people eat fewer calories and lose weight, but also because the diet itself changes how the body processes food. People’s blood sugar doesn’t spike as high after meals, and their insulin levels stay lower.

For brain diseases like Alzheimer’s and Parkinson’s, early research suggests keto might help. The theory is that when your brain uses ketones for energy instead of glucose (regular sugar), it might work better and get better blood flow. Some studies show improvements in thinking and memory, but these findings are still preliminary.

For mental health conditions like depression and bipolar disorder, there are some promising early results, but these come from small, uncontrolled studies. This means we can’t be confident yet that the diet actually causes the improvement.

For cancer, the idea is interesting: since cancer cells love glucose (sugar), maybe starving them of carbs could slow them down. However, there’s no solid proof yet that keto actually helps treat cancer in people.

The research shows that different people respond very differently to the keto diet. Some people’s bodies adapt quickly and show big improvements, while others see smaller changes. This variability makes it hard to predict who will benefit most. Additionally, most studies only lasted a few weeks or months, so we don’t know if the benefits continue over years.

The keto diet isn’t new—it’s been used for nearly 100 years to treat epilepsy, and it works very well for that. This review shows that scientists are now testing whether it might help with other diseases. Some findings match what we’d expect based on how the diet works, but many results are still preliminary compared to what we know about other treatments.

The biggest limitation is that most studies were too short to see long-term effects. Many studies also didn’t have a control group (people eating normally) to compare against. People often don’t stick to the keto diet perfectly, which makes results messy. Different studies used different versions of the diet, making it hard to compare them. Finally, most studies involved small numbers of people, so results might not apply to everyone.

The Bottom Line

For type 2 diabetes and obesity: The keto diet may help, and it’s worth discussing with your doctor as a possible option alongside standard treatments (moderate confidence). For Alzheimer’s and Parkinson’s: Early results are interesting, but don’t switch to keto instead of proven treatments—talk to your neurologist first (low confidence). For mental health conditions: Don’t use keto as a replacement for psychiatric medications or therapy; it might be a helpful addition, but more research is needed (very low confidence). For cancer: Don’t use keto as a cancer treatment; it might be studied as an addition to standard cancer care in the future, but it’s not proven (very low confidence).

People with type 2 diabetes or obesity should talk to their doctor about whether keto might help them. People with Alzheimer’s, Parkinson’s, depression, or cancer should not use keto as their main treatment, but could ask their doctors if it might help alongside standard care. People taking medications should be especially careful, as keto can affect how some medicines work.

For weight loss and blood sugar: You might see changes within 2-4 weeks, but the biggest benefits usually appear after 2-3 months. For brain health: Any benefits would likely take months to appear. For mental health or cancer: We don’t have enough information to predict timelines.

Want to Apply This Research?

  • If trying keto with your doctor’s approval, track daily carbohydrate intake (aim for under 50 grams), weight weekly, and blood sugar levels if diabetic. Record energy levels and mood daily to notice patterns.
  • Start by identifying and replacing high-carb foods (bread, pasta, rice, sweets) with keto-friendly alternatives (vegetables, eggs, fish, nuts). Use the app to log meals and get real-time feedback on whether you’re staying in ketosis range.
  • Check in monthly with trends in weight, energy, and any symptoms. If you have diabetes, monitor blood sugar closely and share results with your doctor. Track adherence to the diet and note any side effects like fatigue or digestive changes.

This review summarizes research on the ketogenic diet for various diseases, but it is not medical advice. The ketogenic diet is a significant dietary change that can affect medications, blood sugar levels, and overall health. Before starting a ketogenic diet, especially if you have diabetes, heart disease, kidney disease, or take medications, you must consult with your doctor or registered dietitian. The research reviewed here shows promise in some areas but lacks sufficient evidence for routine clinical use in most conditions beyond epilepsy. Do not use the ketogenic diet as a replacement for proven medical treatments for serious conditions like cancer, Alzheimer’s disease, or mental illness without explicit guidance from your healthcare team.