How Does The Ketogenic Diet Affect Insulin Resistance?

Insulin resistance is a common metabolic dysfunction that may contribute to various chronic conditions, such as type 2 diabetes, cardiovascular disease, and obesity. Recent studies show that at least 25% of adults in the United States who do not have diabetes are insulin-resistant. 

Insulin resistance occurs when cells do not respond effectively to insulin. This can lead to increased insulin production, resulting in chronically high insulin levels. This article will discuss, based on recent evidence and expert opinions, how a ketogenic diet may help improve insulin sensitivity and support the management of insulin resistance.

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What Is Insulin Resistance?

Insulin is a hormone with two main functions:

• Helps manage blood glucose levels 
• Acts as a signaling molecule for cells in many organs

Insulin resistance represents a metabolic disruption occurring when body cells do not respond well to insulin stimulation. Understanding insulin resistance requires understanding the physiology of insulin. 

Insulin is released by pancreatic beta cells in response to a rise in blood glucose. When a person eats carbohydrates, and the body metabolizes them, blood glucose rises, which signals the pancreas to release insulin. Insulin then helps restore blood glucose to appropriate levels by directing cells on how to use it: either to shuttle it to various organs as energy or store the glucose as fat (adipose tissue).

Insulin resistance occurs when at least one of these happens:

• When blood glucose remains consistently elevated,
• When the pancreas is constantly stimulated to release insulin or
• When cellular receptors are less responsive to insulin stimulation.

Causes and Consequences of Insulin Resistance

Lifestyle Factors: 

• Diets high in processed foods, including added sugars, refined carbohydrates, and processed meats, may lead to higher insulin secretion, which can contribute to a proinflammatory state and increase the risk of insulin resistance. 
• Physical inactivity may increase the risk of developing insulin resistance. 
• Weight gain resulting in obesity may independently increase the risk of insulin resistance.

Genetic Factors: 

Genetic predispositions may also increase the risk of insulin resistance, including altered genes for these functions: 

• Insulin signaling or lipid metabolism 
• Mitochondrial activity
• Inflammatory mediators

Hormonal Imbalances: 

Imbalances of neuroendocrine hormones can significantly affect insulin resistance by influencing insulin release from the pancreas: 

• Glucagon-like peptide-1
• Glucose-dependent insulinotropic peptide (GIP)
• Ghrelin
• Peptide YY 

Hormone imbalances in conditions like polycystic ovarian syndrome (PCOS) can lead to elevated insulin levels and decreased insulin activity, potentially increasing the risk of weight gain and type 2 diabetes mellitus.

What Is the Ketogenic Diet?

Low carbohydrate diets generally include < 40% of calories from carbohydrates, 25-30% of calories from protein, and 30-40% of calories from fat. Ketogenic diets are even lower in carbohydrates, with 5-10% of calories from carbohydrates, 20-30% of calories from protein, and 60-75% of calories from fat.

Ketogenic Diet and Metabolic Health

The goal of a ketogenic diet is to induce nutritional ketosis, whereby insulin secretion is significantly reduced, and the body relies on stored fat for energy rather than glucose from carbohydrates. Stored fat is broken down into fatty acids, which are converted into ketones in the liver to be used as the body’s primary source of energy.

A ketogenic diet may support weight loss through several possible mechanisms.

• Decreased insulin release may lead to increased fat breakdown (lipolysis)
• Increased gluconeogenesis to provide glucose to the brain (gluconeogenesis burns a lot of energy)
• Direct appetite suppression
• Volume (water) loss
• Higher protein intake may increase diet-induced thermogenesis

Potential Benefits for Insulin Sensitivity

Low carbohydrate diets have been shown to support improved insulin sensitivity, especially in overweight or obese individuals. A lower carbohydrate intake may help reduce blood sugar levels, thereby lowering insulin secretion. 

As insulin levels are reduced, insulin sensitivity may improve. The added benefit of weight loss from low carbohydrate diets is that they may provide additional support for insulin sensitivity improvement. 

Research Evidence

Recent studies on the ketogenic diet's impact on insulin sensitivity and resistance show mixed results. 

• Positive outcomes in individuals with type 2 diabetes mellitus and/or obesity include these:

• Lower A1c levels
• Improved insulin sensitivity
• Reduced fasting insulin levels

• Potential negative outcomes include these:

• Increased LDL cholesterol levels
• Adverse cardiovascular effects
• Nutrient deficiencies
• Challenges with long-term adherence

Clinical Perspectives and Real-World Applications

Ketogenic Diet in Managing Diabetes

Research suggests the ketogenic diet may be effective in supporting the management of type 2 diabetes mellitus in the following ways:

• Significant improvements in blood glucose
• Lower HbA1c levels
• There is less need for antidiabetic medications
• Weight loss
• Reduced insulin resistance

Expert Opinions and Recommendations

Many health professionals suggest the ketogenic diet for individuals who have or are at risk for developing insulin resistance. However, it is crucial to follow a ketogenic diet under medical supervision to monitor for potential side effects, like elevated LDL cholesterol and nutrient deficiencies. Close monitoring allows for individualized dietary adjustments and may help lower the risk of adverse cardiovascular events and hypoglycemia.

Considerations and Precautions

While ketogenic diets may be beneficial, they have associated risks and potential negative side effects. 

• Nutrient deficiencies are possible, including fiber, vitamins, and minerals. 
• Elevated cholesterol levels can occur with higher consumption of saturated fats.
• Healthy individuals may have paradoxical reactions to ketogenic diets, potentially leading to insulin resistance and impaired glucose metabolism. 
• Long-term adherence can be difficult, as it limits food options.

Using ketogenic diets to support the management of type 2 diabetes may be an effective strategy for some individuals. Nutritional ketosis involves lower levels of ketones in the blood than are seen in ketoacidosis with severe diabetes, but blood acid levels may still need to be monitored. In addition, diabetic medications must be carefully managed when following a ketogenic diet to prevent hypoglycemia.

When considering a ketogenic diet, implementing personalized dietary approaches that consider other health conditions, personal preferences, and unique goals will facilitate optimal adherence and best outcomes.

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Key Takeaways

Ketogenic diets:

• May support improved insulin sensitivity, reduced insulin resistance, and improved blood sugar in people with type 2 diabetes mellitus and/or obesity.
• Have been shown to promote weight loss, which may further support insulin resistance management.
• May have possible adverse effects, such as an increased risk of high LDL cholesterol, cardiovascular disease, and nutrient deficiencies.
• Present sustainability concerns long-term, so finding the proper balance of macronutrients through a personalized nutrition plan is necessary to optimize individual outcomes.