Is Carnivore Diet Truly a Zero-Carb Diet?
Posted by Mira on May 26, 2025 in learn
Introduction
The carnivore diet, which exclusively consists of animal products, is often marketed as a zero-carbohydrate diet. Proponents argue that it simplifies eating by eliminating all plant-based foods, focusing solely on meat, fish, and sometimes dairy. However, the reality of its carbohydrate content is more nuanced than it appears. Let's delve into whether the carnivore diet is truly carb-free and explore the implications for health.
Fresh Meat Isn’t Truly "Zero Carb", but Aged Meat Is Almost
At first glance, the carnivore diet appears to be devoid of carbohydrates, as it excludes all plant-based sources like fruits, vegetables, and grains. However, fresh meat contains trace amounts of carbohydrates in the form of glycogen—a stored form of glucose found in animal muscles and liver. This glycogen is rapidly depleted after the animal is slaughtered, but in the immediate aftermath, it can contribute a small amount of carbohydrates to the diet.
For example, studies on meat composition reveal that fresh liver and muscle tissue may contain residual glycogen, though typically less than 1% of total weight—making it a negligible source compared to plant foods.
As meat undergoes aging processes such as wet or dry aging (including brining, curing, or smoking), glycogen is further broken down by bacteria, reducing even these trace amounts. However, this process may also increase endotoxin levels, which can have other health implications.
Our ancestors hunted live animals, consuming them fresh—thus accessing glycogen-rich meat. This likely provided them with sufficient carbohydrates to meet their energy needs. In contrast, modern consumers typically eat aged meat, which contains far less glycogen.
Can we the modern humans rely on a zero-carb diet to provide us with sufficient carbohydrates?
Metabolic Adjustments to a Low-Carb Diet
Our body’s response to a lack of dietary carbohydrates is significant.
On a carnivore diet, the absence of exogenous carbohydrates forces the body to rely on gluconeogenesis, a process in which the liver converts non-carbohydrate substrates like amino acids and glycerol into glucose. This is essential for maintaining blood sugar levels, especially for the brain and red blood cells, which rely on glucose as a primary fuel source.
Health Impacts of a Low-Carb Diet
This metabolic shift can have downstream effects. The conversion of T4 to T3—the active thyroid hormone—is partly dependent on glucose availability. Research indicates that low-carbohydrate diets can lead to decreased T3 levels, potentially affecting metabolic rate and energy levels. You can eat all the meat you want, but without sufficient carbohydrates, you may develop signs of hypothyroidism, including energy crashes and metabolic slowdown.
Moreover, the high protein intake typical of the carnivore diet can upregulate gluconeogenesis, leading to increased ammonia production. The body must then process this ammonia, which can place strain on the liver and kidneys over time. Additionally, cortisol levels may rise as part of the body’s stress response, which can further impact hormonal balance and overall health.
Personal Experience
After being on a carnivore diet for a while, I initially felt energetic. However, over time, I began to struggle with low energy after meals. During my gym sessions, I felt sluggish and slow. To address this, I started adding fruits—such as apples and berries—to my first meal of the day, after working out. This simple change made a noticeable difference and helped me feel more energetic almost immediately.
My understanding is that my glycogen stores had become depleted, and I needed to replenish them. I’ve realized that I can't allow my glycogen levels to drop so low that I feel sluggish and underpowered.
I believe that if someone has no metabolic issues and is very active in the gym, they should pay close attention to their energy levels and carefully consider whether a strict carnivore diet is right for them.
Conclusion
While the carnivore diet is marketed as a zero-carb approach, it is not entirely free of carbohydrates due to the presence of glycogen in fresh meat—though only in small amounts.
The metabolic and hormonal adaptations required to maintain energy on such a diet can have important implications, particularly concerning thyroid function, ammonia processing, and hormonal balance.
