Insulin resistance is a common metabolic dysfunction that gives rise to many chronic illnesses, 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 fail to respond to insulin. This causes more insulin to be produced, leading to chronically high insulin levels. This article will discuss, based on recent evidence and expert opinions, how a ketogenic diet can be used to improve insulin sensitivity and potentially treat insulin resistance.
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What Is Insulin Resistance?
Insulin is a hormone with two main functions:
- Reduces blood glucose levels
- Serves as a signaling molecule for cells in many organs
Insulin resistance represents a metabolic disruption occurring when body cells fail to respond 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, lead to higher insulin secretion, which results in a proinflammatory state and increases the risk of insulin resistance.
- Physical inactivity increases the risk of developing insulin resistance.
- Weight gain resulting in obesity independently increases the risk of insulin resistance.
Genetic Factors:
Genetic predispositions 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 increase insulin resistance by affecting 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 cause elevated insulin levels and decreased insulin activity, further raising 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 induces weight loss by several possible mechanisms.
- Decreased insulin release leads 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 improve insulin sensitivity, especially in overweight or obese patients. A lower carbohydrate intake helps reduce blood sugar levels, thereby lowering insulin secretion.
As insulin levels are reduced, insulin sensitivity can improve. The added benefit of weight loss from low carbohydrate diets is that they provide additional insulin sensitivity improvement.
Research Evidence
Recent studies on the ketogenic diet's impact on insulin sensitivity and resistance show mixed results.
- Positive outcomes in patients 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 is effective in managing 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 recommend 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 lowers 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 patients may have paradoxical reactions to ketogenic diets, leading to insulin resistance and impaired glucose metabolism.
- Long-term adherence can be difficult, as it limits food options.
Using ketogenic diets to manage or prevent type 2 diabetes may be an effective strategy for some patients. 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:
- Have 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, further improving insulin resistance.
- 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 patient outcomes.
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