Dr. Rob Cyus, also known as the “carb addiction doc,” discusses the complexities of the carnivore diet, particularly when it “goes wrong” over time. While the carnivore diet is praised for its rapid benefits in improving insulin resistance, weight loss, reducing inflammation, and mitigating chronic diseases, prolonged adherence can result in metabolic issues in certain populations, primarily those genetically predisposed to insulin suppression. He differentiates between a strict pure carnivore diet (consisting only of animal products) and a carnivore-based diet (which may include small amounts of plant-derived foods like avocado and coffee). Dr. Cyus emphasizes that human nutritional biology is dynamic, and insulin plays a critical role in maintaining metabolic health. Long-term carnivore dieters can experience insulin suppression due to downregulation of GLP-1 hormone, leading to impaired glucose disposal, elevated blood sugar, triglycerides, testosterone reduction, muscle loss, and increased cardiovascular risk, particularly in a subgroup known as lean mass hyperresponders (LMHRs). He presents ethnogenetic differences in metabolic responses—Eskimo (obesogenic), equatorial (diabetogenic), and subtropical (healthiest) phenotypes—to explain varied risk profiles. Importantly, Dr. Cyus stresses regular monitoring of blood work and advanced cardiovascular testing (like CTA scans to detect soft plaque) for those on long-term carnivore diets. He suggests cautious reintroduction of pure carbohydrates (not plants) and the potential use of micro-dosed GLP-1 medication to restore insulin function in insulin-suppressed individuals. Overall, he advocates for a responsible carnivore approach with individualized monitoring to prevent long-term harm while enjoying the benefits of the diet.

Highlights

• 🥩 Carnivore diet offers rapid benefits for insulin resistance, weight loss, and inflammation reduction.
• ⚠️ Long-term pure carnivore diet may cause insulin suppression and metabolic disturbances in some people.
• 🧬 Genetic body types (Eskimo, equatorial, subtropical) influence individual response and cardiovascular risk.
• 🔬 Advanced cardiovascular imaging like CTA is crucial for detecting soft plaque in long-term carnivore dieters.
• 🍚 Reintroducing low-dose pure carbohydrates can help restore insulin function in insulin-suppressed individuals.
• 🩸 Monitoring blood work and hormone levels is essential for safely following a carnivore or carnivore-based diet.
• 💡 Insulin suppression leads to muscle loss, increased blood sugar, and higher cardiovascular risk despite high LDL. Key Insights
• 🔥 Insulin suppression as a metabolic inflection point: The carnivore diet initially improves insulin sensitivity but over time may push certain individuals into a state of insulin suppression due to downregulated GLP-1 signaling. This leads to impaired glucose disposal, increased blood sugar, and risk factors for cardiovascular disease despite continued dietary adherence. This dynamic illustrates that metabolic health is a moving target requiring ongoing assessment.
• 🧬 Ethnogenetic variation shapes diet outcomes: Dr. Cyus explains three major body types shaped by evolution—Eskimos with high insulin production and fat storage capacity, equatorial populations with low insulin capacity prone to blood sugar spikes and cardiovascular disease, and subtropical populations with more balanced metabolic and hormonal profiles. These differences profoundly affect how individuals tolerate a carnivore diet and their risk of complications, underscoring the need for personalized nutrition.
• 💔 High LDL is not the sole cardiovascular risk factor: The Feldman lean mass hyperresponder studies highlighted that LDL levels alone do not predict cardiovascular risk in carnivore dieters. Instead, rising soft (non-calcified) plaque detected by CTA scans and insulin/glucagon imbalance are key indicators. LDL must be interpreted contextually, especially when accompanied by signs of insulin suppression.
• 🥚 Distinguishing pure carnivore from carnivore-based diets aids flexibility: While pure carnivore excludes all plant foods, the carnivore-based approach allows limited plant foods (coffee, avocado) without losing benefits. This distinction provides more tailored options to prevent or correct metabolic side effects without abandoning the core benefits.
• 🍚 Controlled carb reintroduction is a therapeutic strategy: Slowly adding pure carbohydrate sources like milk, honey, or small amounts of starch can reactivate GLP-1 release and insulin signaling, restoring metabolic balance. This is supported by studies like Isabella Cooper’s work showing better insulin/glucagon dynamics and endurance performance in low-carb athletes who consume modest carbs.
• 📊 Comprehensive monitoring is critical: Beyond standard blood work, methods like extended oral glucose tolerance tests and CTA scans for soft plaque are vital for early detection of metabolic shifts and cardiovascular risk, especially in long-term carnivore followers. Personalized, expert interpretation of these tests enables timely interventions to prevent irreversible damage.
• ⚖️ Hormonal interplay affects muscle mass and overall health: Insulin regulates testosterone production through aromatase activity; suppression of insulin during extended carnivore diets can lower testosterone, causing muscle loss and fatigue despite high protein intake. This paradox leads to a vicious cycle of increased lean protein consumption worsening insulin suppression, highlighting the complexity of hormonal regulation under extreme diets.

Dr. Cyus urges carnivore dieters to balance enthusiasm with responsibility, monitoring their metabolic health closely and being open to dietary adjustments or medical interventions to maintain long-term wellness. His pragmatic approach blends scientific evidence with evolutionary biology and clinical experience to guide those seeking the benefits of carnivory while avoiding its pitfalls.