Often when people follow some form of a low-carb diet, they focus on monitoring certain things through blood testing to get some insight into the effects of diet. Blood testing provides some data and often can help to troubleshoot problematic health issues. Before I get into some of the common observations that I’ve made about carnivore dieters, let me put some things into perspective.
When you have your blood drawn, its contents are representative of what is being transported via your blood during that exact moment in time. Many, if not most, of the things that can be measured in the blood can change on a weekly, daily, hourly, and even momentary basis. For instance, blood cholesterol can change dramatically over a few days, hormones can change by the hour, and liver enzymes or inflammatory markers can go up or down based on recent activity or exercise levels. Lab values can be significantly affected by many things, including stress, sleep, illness, activity, exercise, weather, temperature, time of day, and time of year. So, trying to attribute any one particular laboratory reading exclusively to diet can be problematic.
Just as the nutrition science–based food recommended daily allowances were based on a population that was arguably sick from eating a high-carbohydrate, grain-based diet, many of the common laboratory reference ranges were based on that same population. We truly do not have a good set of reference ranges for the populations who follow the low-carbohydrate and carnivore diets. With this in mind, I want to share some of the areas where labs for carnivore dieters can diverge from the general population.
Blood lipids probably cause the most concern for both patients and their physicians. First of all, blood lipid levels are dynamic; they can vary fairly significantly over a matter of even a few days. Your total cholesterol on Wednesday may be remarkably different the following Tuesday. Let’s assume that the numbers you get represent a daily average. (However, this assumption is likely false.) When we look at the lipid number for a carnivore dieter, we often see elevated total and LDL cholesterol; this is not always the case, and often LDL/total cholesterol will be largely unchanged or even lower.
Another common finding among carnivore dieters is a general trend toward elevated HDL, the so-called good cholesterol, and generally lower triglycerides. In general, higher HDL and lower triglycerides are thought to represent an improvement in cardiovascular risk, but this is not absolute, particularly regarding the HDL. As I’ve already mentioned, it’s important that you realize that large energy shifts and weight loss can be responsible for unexpected numbers, such as higher than expected triglycerides, particularly at the beginning of a transition to the carnivore diet. I often suggest that people wait six months or more before getting routine labs after starting the diet, unless there’s a compelling reason to do it earlier, such as to address an illness.
Glucose control is important, and generally speaking, a carnivore diet tends to lead to very well-controlled glucose numbers. If you’re going to talk about glucose, then you definitely need to be aware of your insulin status. When you look at a blood glucose reading in isolation, you leave out a major part of the story of blood sugar control, potential diabetes, and other chronic disease risks. If you’re going to worry about heart disease, insulin sensitivity is one of the most important modifiable risk factors you can be concerned with. It’s right up there with smoking, and it’s far more important than relative cholesterol levels. You can use a fasting insulin level with a fasting glucose level to calculate something called a HOMA-IR score, which is one of several reasonable measures of insulin sensitivity.
In general, a carnivore diet tends to lead to improved insulin sensitivity over the long term. Glucose tends to remain stable for people on the carnivore diet because the glucose the body is using is not being ingested; it’s being produced mostly from protein, a small amount of fat, and a few other sources, such as lactate, via a process generally described as gluconeogenesis. Gluconeogenesis is probably the most precise way to control glucose regulation, and in the long term, it leads to well-controlled and stable blood glucose numbers. People with both type 1 and type 2 diabetes also note that in the long term they tend to see excellent blood glucose control, although it may take a few months for the level to normalize.
Liver function studies tend to be normal for people on the carnivore diet, and the assumption that increased protein is damaging to the liver is based upon a fallacy. NAFLD (non-alcoholic fatty liver disease) is an increasingly common diagnosis. Fortunately, we know from observations of carnivore populations and by extrapolating data from low-carbohydrate studies that a carnivore diet tends to improve this problem. Liver function tests can be slightly elevated for several reasons, and if you’re having them evaluated, you should be aware of benign reasons for their elevation. One of the more common reasons is recent intense exercise, which can result in slight elevations of these enzymes for up to a week.
In a similar vein, markers of inflammation, such as C-reactive protein, can show a transient elevation after exercise or other acute stresses on the body. This marker and other inflammation labs can be used as risk factors for predicting cardiovascular or other disease potentials. Once again, it appears that a carnivore diet tends to lead to low levels of inflammatory markers.
Kidney function is often a concern with higher protein diets, but the concern stems from data from animal studies that haven’t been replicated with humans. In general, the consensus is that high-protein diets do not damage kidneys. Some people still are concerned that an already damaged kidney will fail more quickly in the presence of higher levels of protein, but that data is tenuous at best. We have some reports of improved renal function in people who’ve followed a carnivore diet. If you have compromised renal function and are concerned that consuming too much protein while on a carnivore diet might be problematic, it’s worth your effort to track the function over time.
Thyroid function is generally improved on a carnivore diet, and we have observed improvements in autoimmune-related issues such as Hashimoto’s thyroiditis. One interesting thing to note is that thyroid hormone, particularly T3 levels, may seem to be low, but the clinical function is noted to be good. This likely represents a decreased requirement for circulation of the hormone or an increase in receptor sensitivity. Therefore, you should not need a supplement in the absence of a clinical need.
Similarly, when people follow a carnivore diet, reproductive hormones tend to normalize and function optimally. It becomes very important to consider clinical function as we assess particular hormone levels. Both men and women note improvements in libido and clinical testosterone function when they follow a carnivore diet, particularly after they’ve moved beyond the adaptation phase.
Iron deficiency is one of the most common deficiency problems in the world, and a carnivore diet is undoubtedly the most efficacious way to prevent that problem because it’s tremendously high in bioavailable heme iron. On the other hand, too much iron, particularly when stored in excess quantities in the tissue, has been associated with some health problems, such as diabetes, cardiac disease, or liver disease.
Fortunately, excess iron levels don’t seem to occur to any significant degree on a carnivore diet. It’s likely that underlying metabolic disease and inflammatory states contribute to excess iron storage. In general, a carnivore diet tends to improve those conditions, and that may be the reason why high storage levels as assessed by serum ferritin don’t seem to be a problem, even though carnivore dieters have a relatively high iron intake.
Miscellaneous Health Markers
In general, you can expect both red and white blood cell counts to fall within the normal ranges. However, you may see slightly lower white blood cell counts, which may be associated with a generally lower inflammatory state. Levels of serum electrolytes, such as sodium, potassium, chloride, calcium, and magnesium, tend to be normal. Our bodies do a pretty good job of maintaining these in fairly narrow physiologic ranges.
Some people express concern that a carnivore diet can lead to an acidic environment, but our blood pH is aggressively controlled and very tightly regulated. As long as we have functioning lungs and kidneys, we can keep our blood pH right where it needs to be regardless of dietary input.
The concerns about acids leaching minerals from our bones for buffering purposes are unfounded. Higher protein diets ultimately lead to better long-term bone health, especially because our bones are approximately 40 percent protein.