You’re no doubt familiar with the external effects of keto diets, like weight loss, energy boosts, and improved mental clarity. But we don’t always talk about its internal impacts — namely, its effect on your blood that might concern traditional doctors.
That’s because a low-carb diet will change more than just your A1C. Some of the changes you experience may, at first, seem like cause for alarm.
That’s why you should know the science behind the diet, plus what to expect up-front as you transition.
Below is a detailed list of the biomarkers you should expect to change on a ketogenic diet so you’re prepared for future conversations with your doctor.
First: a quick note on bioindividuality
Bioindividuality posits that every body is different, so no two people will have the same response to a diet. Nowhere is this more obvious than with low-carb ketogenic diets. Some people may never see extreme fluctuations in their bloodwork, while others notice changes within the first few weeks.
I strongly believe the only way to know is to regularly test and look for differences or abnormalities.
So in your next metabolic panel, keep on the lookout for these changing biomarkers.
Most common biomarkers
These are the changes you’re most likely to see first:
Fasting insulin levels
You already know that ketogenic diets reduce fasting glucose. It’s hard to spike your blood sugar on less than 25 grams of carbs per day, after all.
But ketogenic diets can also help reduce fasting insulin, which is responsible for pushing blood glucose into your cells. High insulin levels typically indicate metabolic disruption, which is a strong biomarker for metabolic syndrome and typically requires immediate intervention.
Ketogenic diets can help to reduce insulin levels by reducing the amount of sugar in your blood and making your cells more sensitive to insulin. You can expect to see improvements within four weeks, often with lasting improvements to postprandial insulin sensitivity.
Inflammation markers (CRP)
More and more studies suggest that low-carb, high-fat diets can significantly decrease inflammation markers in the body. There are a few different ways to measure inflammation (including complex measurements such as erythrocyte sedimentation rate and cytokines) but this article will focus on the most common: C-reactive protein, typically shortened to CRP.
CRP is a type of liver protein that is secreted in high quantities as response to high levels of inflammation. For context, a healthy range of CRP should be less than 0.3 milligrams per deciliter (mg/dL). Anything at 1.0 mg/dL or higher could indicate diabetes, obesity, or other inflammation-causing factors. If your score is at or above 3.0 mg/dL, you might be at high risk for cardiac events.
Long-term ketogenic diets can reduce CRP scores by a magnitude of 35% to 40% within 12 months — comparable to some of the highest potency statins on the market. But unlike statins, ketogenic diets also reduce white blood cell counts. They also don’t lead to the serious side effects you might find with traditional cholesterol-lowering medications.
Which leads to the next biomarker…
Cholesterol
It’s a well-known phenomena that ketogenic diets often increase total cholesterol levels. These elevated numbers might put you or your doctor on high alert, and wonder if you need to introduce carbohydrates back into your diet to reduce your total numbers.
However, studies show that statin therapy is not necessary for someone with high LDL-cholesterol on keto. This is true for three reasons:
- Low-carb diets that are high in saturated fat will change the size of your cholesterol particles. These will be large, fluffy, and far less likely to stick compared to small, dense particles, which will raise your risks for heart disease.
- Ketogenic diets improve your triglyceride/HDL ratio. Low levels indicate you’re well within a heart-healthy range and unlikely to experience the same effects as someone following a Standard American Diet (SAD).
- High LDL on its own is rarely a solid indicator of heart disease risk. Case in point: 75% of people hospitalized for heart attacks have what’s considered a ‘normal’ range of LDL cholesterol.
Note: you might find your LDL cholesterol seems extremely high, even compared to others on the ketogenic diet. These are what we refer to as lean mass hyperresponders: low-BMI, highly athletic individuals with LDL anywhere from 300 to 500 mg/dL.
We don’t have evidence LMHRs are at a higher risk for heart disease, but we’re certainly performing more research to find out. If you think or know you’re in this category, it’s best to keep tabs on your numbers, and stay abreast of new research as it’s released.
Other biomarkers to keep in mind
Let’s shift for a moment from blood serum to hormones.
There are a few noticeable differences you might find in your labs:
Testosterone
Some research suggests that a low-carb diet can help to balance the level of free testosterone in your blood. This phenomenon applies to both men and women, although the effects may be different depending on sex.
For active men, keto can increase testosterone. This is likely due to the relationship between fat and protein on hormone synthesis.
For women, keto may reduce free testosterone in as little as 45 days. This is particularly helpful for women suffering from hormonal imbalances such as polycystic ovarian syndrome (PCOS), which could have further health effects as well.
Cortisol levels
You should know that cortisol, better known as the stress hormone, may increase initially while beginning a keto diet. This isn’t necessarily groundbreaking — many types of diets increase psychological stress and increase cortisol production. This includes metabolically-regenerative actions such as intermittent fasting.
Another oft-cited study found low-carb diets only lead to increased cortisol production within the earliest stages of ketosis. This is thought to be a temporary effect, with resting cortisol returning to baseline after three weeks of adhering to a low-carb diet.
With this in mind, your cortisol levels will likely remain in a normal range so long as you prioritize eating enough and exercising. Cortisol production will also change with body composition. Those with higher levels of visceral fat tend to release more cortisol, and weight loss may assist with modulating its production.
Now, there’s a lot more we have to understand about the interplay between cortisol and low-carb diets, including differences between sexes and dietary macros. But for now, it’s still something to monitor in your own blood work.
Ordering a blood panel to track your progress
If you’re serious about keto and want it to be a lifestyle instead of a diet, you need to make bloodwork a habit rather than a special occasion. This means regularly scheduling labs to keep an eye out for abnormalities, as well as working with a doctor who can help guide you in the right direction.
Now, there are plenty of tests for metabolic health, but only a few that matter in the earliest stages.
I cover the three blood labs you shouldn’t order (and three you should) in this dedicated guide.
