Reviewed by Dr. Eric Westman, MD, MHS: (November 2025)
The ketogenic or “keto” diet has gained significant attention for its remarkable effects on metabolic health. While often associated with weight loss, its true power lies in its ability to address the underlying metabolic dysfunctions that drive common conditions, like polycystic ovary syndrome (PCOS), type 2 diabetes, and metabolic syndrome. The key to its success is a powerful metabolic shift that switches the body’s main fuel from glucose to fat and ketones. This helps to target insulin resistance—the common thread linking all three conditions.
On a standard high-carbohydrate diet, our bodies primarily run on glucose, which is converted from the carbohydrates we eat. The hormone insulin is responsible for moving glucose from the bloodstream into cells for energy or for storage. In conditions of insulin resistance, cells stop responding effectively to insulin, which means the pancreas has to produce more and more of it in order to send a stronger signal. This leads to a vicious cycle of high blood sugar, high insulin, increased fat storage, and hormonal chaos. The keto diet breaks this cycle by dramatically cutting carbohydrate intake, which is the key change that allows the body to shift into a metabolic state called ketosis.
In ketosis, the body uses fat as its main fuel and the liver begins producing ketones—molecules that can be used for energy by the brain and most other organs and tissues. This metabolic switch significantly lowers blood glucose and insulin levels, and this change has profound therapeutic benefits for metabolic diseases.
The Ketogenic Diet and Polycystic Ovary Syndrome (PCOS)
PCOS is a common endocrine disorder in women, strongly linked to insulin resistance. Women with PCOS often experience irregular menstrual cycles, weight gain, infertility, and elevated androgens (male sex hormones). The ketogenic diet’s impact on lowering insulin and helping to balance hormones makes it a highly effective tool for improving these symptoms.
By limiting carbohydrates, the keto diet directly lowers blood sugar and insulin levels. This improved insulin sensitivity helps to reverse the hormone imbalances at the root of PCOS. High insulin levels can stimulate the ovaries to produce excess testosterone, contributing to symptoms like excess hair growth and acne. By bringing insulin levels down, the diet can help normalize the production of androgens and improve the balance of other hormones critical for ovulation, such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
A well-formulated ketogenic diet also aids in significant and sustainable weight loss, a crucial factor in managing PCOS. Losing even a small percentage of body weight can dramatically improve symptoms and restore regular menstrual cycles. This diet’s base of protein and fat promotes a feeling of fullness, which can help control appetite and reduce calorie intake. Numerous studies have shown that women with PCOS who follow a keto diet experience a reduction in testosterone levels and a return of regular cycles—with some even conceiving easily and having healthy pregnancies after struggling with infertility for years.
The Ketogenic Diet and Type 2 Diabetes
Type 2 diabetes is defined by persistently high blood sugar levels due to insulin resistance. The keto diet is one of the most powerful dietary interventions for this condition because it directly addresses the cause of the high blood sugar: excess carbohydrates.
The most immediate benefit of a ketogenic diet for type 2 diabetes is the lowering of blood glucose. By removing the primary dietary source of glucose, this way of eating prevents the damaging blood sugar spikes and sustained high levels that are characteristic of the disease. This leads to a substantial improvement in HbA1c, a key marker of long-term blood sugar control.
For many people with type 2 diabetes, a ketogenic diet can lead to a significant reduction in medication needs, often allowing them to reduce or completely stop taking glucose-lowering drugs, including insulin. This is a direct result of the body’s improved insulin sensitivity. Weight loss, a common and rapid side effect of the diet, further enhances this effect. Studies have shown that ketogenic diets are more effective than low-fat or low-calorie diets for improving glycemic control. By allowing the body to run on fat instead of sugar, the diet can effectively put type 2 diabetes into remission, particularly for those who have been recently diagnosed.
The Ketogenic Diet and Metabolic Syndrome
Metabolic syndrome is not a single disease but a cluster of risk factors that dramatically increase the likelihood of developing heart disease, stroke, and type 2 diabetes. These risk factors include high blood pressure, high blood sugar, excess abdominal fat, and high triglycerides coupled with low HDL-cholesterol. The ketogenic diet provides a comprehensive approach to managing all of these components.
The diet’s effectiveness in tackling metabolic syndrome stems from its ability to resolve insulin resistance. By improving how cells respond to insulin, it naturally improves blood sugar control and reduces the amount of fat stored, particularly in the abdominal area. This visceral fat, which surrounds internal organs, is a major driver of chronic inflammation and insulin resistance. Reducing it is a critical step toward better health.
Beyond weight loss and blood sugar control, a well-formulated ketogenic diet can also significantly improve lipid profiles. While many people worry about the high-fat nature of the diet (in particular because it allows for animal fats, like butter, tallow, and lard), research often shows it leads to beneficial changes: a reduction in harmful triglycerides and an increase in HDL-cholesterol. These changes are crucial for lowering cardiovascular risk. Finally, the primary ketone body—beta-hydroxybutyrate (BHB)—has anti-inflammatory properties. Chronic, low-grade inflammation is a key feature of metabolic syndrome. By directly inhibiting inflammatory pathways, BHB adds another layer to the keto diet’s therapeutic benefits.
Final Thoughts and Considerations
While the evidence for the ketogenic diet’s benefits on these conditions is robust and growing, there are a few things you need to be aware of before starting this way of eating. It’s understandable that such a significant change in your diet might cause some issues at first and that your body might need some time to adjust. This adaptation period is often called the “keto flu“. All it really is, is your body getting accustomed to burning fat for fuel rather than carbs.
And if you take medication for high blood pressure or for diabetes—especially insulin—it’s essential that you have medical supervision before starting. Keto is so powerful for lowering blood sugar that insulin doses may need to be adjusted on the first day you start the diet. Keto works so quickly and begins to improve your health so rapidly that some of your medications may become too strong within a matter of days or weeks, and being overmedicated can cause dangerous issues. But don’t blame the diet for what the meds are doing! A qualified medical professional can help you monitor your progress, adjust your medications, and ensure you are following the diet safely.
Reviewer Bio
Eric Westman, MD, MHS, is an Associate Professor of Medicine at Duke University, the Medical Director of Adapt Your Life Academy and the founder of the Duke Keto Medicine Clinic in Durham, North Carolina. He is board-certified in Internal Medicine and Obesity Medicine and has a master’s degree in clinical research. As a past President of the Obesity Medicine Association and a Fellow of the Obesity Society, Dr. Westman was named “Bariatrician of the Year” for his work in advancing the field of obesity medicine. He is a best-selling author of several books relating to ketogenic diets as well as co-author on over 100 peer-reviewed publications related to ketogenic diets, type 2 diabetes, obesity, smoking cessation, and more. He is an internationally recognized expert on the therapeutic use of dietary carbohydrate restriction and has helped thousands of people in his clinic and far beyond, by way of his famous “Page 4” food list.
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