The Ketogenic Diet has once again gained some attention and become somewhat popular among the fitness community. Not everyone is familiar with this diet, how it works, or the change that occur within the human body. It is my belief that if you’re going to implement a diet that could potentially be dangerous if not executed properly, you should know how that diet works and how it can affect you.

So, without further ado, let’s dive into some info… (As always, I’ll be referencing my info for those of you who are nerds like me.)

So what is ketosis? Ketogenesis? Ketoacidosis? Is there a difference between them?

Ketogenesis is the process of ketone body formation that occurs when the human body is either starving or in an extreme carbohydrate (CHO) deficit. This typically occurs anywhere from 20-50 grams of CHO or less. Ketosis is the state the body is in when there is a presence of ketone bodies in the blood and the body is essentially burning fat for fuel, but the ketone bodies aren’t so high that it’s life threatening or throws off the acid-base balance. Ketosis is usually achieved through a diet with macronutrient ratios of 5-10% CHO, 15-30% PRO, and the rest of the calories coming from fat. Ketoacidosis is a life-threatening condition that usually occurs in those suffering with diabetes, the amount of ketone bodies in the blood is exceedingly high in this condition and it throws off the acid-base balance (hence the “acidosis” in the name).1

As for ketone bodies, these are more complicated, so bear with me. There are 3 primary ketone bodies produced in ketogenesis: acetoacetate, beta-hydroxybutyrate, and acetone. I’m sure most of you are most familiar with acetone. They’re formed when the body is either starving, has had a very low CHO intake, or in those with uncontrolled diabetes (we’ll get more into the specifics of how low of a CHO intake one must have to achieve ketosis later on). The process of ketogenesis is complicated. Lipolysis is occurring due to lack of CHO, there is a high oxidation of fatty acids, so Acetyl-CoA levels rise. There is too much Acetyl-CoA in the liver for it to be properly oxidized via the TCA cycle. The ketone bodies are formed in the TCA Cycle from all of the Acetyl-CoA. The liver makes the ketone bodies, but it can’t actually use them for fuel itself. It sends them to the body’s extrahepatic tissues, which is just a fancy term for tissues that aren’t the liver: the muscles and the brain primarily. Only acetoacetate and beta-hydroxybutyrate can be sent to tissues for energy since they can’t be oxidized by the liver. In short, you pee out acetone. This is also the reason that scientists argue placing the body in ketosis isn’t necessarily dangerous, the body shifts to fat breakdown and uses the ketone bodies the fat breakdown produces for fuel.1

Now you know more about ketosis, I totally get it if you’re lost though. Read that last paragraph as many times as you need to! And feel free to comment or email with questions. Now for the fun stuff:

What are the benefits of a ketogenic diet?

  1. Your body is using fat for fuel.1-3
  2. This diet is [arguably] the most muscle preserving when done correctly.3,7-10
  3. It can help in the treatment of cancer, epilepsy, and even Type 2 Diabetes when done carefully/correctly.1-2
  4. It is a “safe” diet for short-term use, the usual recommended time to utilize this diet is for less than 4 months at a time.2,3


And the negatives?

  1. You may experience headaches, nausea, fatigue, dizziness, brain “fog”, etc.2
  2. Due to ketone bodies, you’ll probably have horrible breath. It usually smells slightly fruity.2
  3. Even in short-term, the Keto Diet can have negative effects on the body: kidney stones, impaired growth in children, osteoporosis, and hyperlipidemia may occur. The reason hyperlipidemia may occur is from the high intake of fat in a keto diet.4
  4. This diet is not safe for long-term use. In the few long-term studies that have been implemented using the Keto Diet, many long-term effects (over a 4-month period) have been found. These include: glucose intolerance, insulin resistance, dyslipidemia (extremely high blood lipid & cholesterol levels), inflammation, signs of liver damage, a reduction in alpha and beta cell presence in the pancreas, as well as conditions that are associated with metabolic syndrome and the development of Type 2 Diabetes.4


And now to the different uses of a ketogenic diet:

Ketosis & Diabetes:

**I want to preface this section with this piece of advice: always consult BOTH your primary medical doctor (MD) and a registered dietitian (RD) if you are ever thinking of trying a ketogenic diet and you have T2DM. I want to stress the importance of seeking guidance from an RD on this matter, they have the knowledge that is required to help advise you. Please see to search for practicing RD’s in your area.**


This particular topic sparked my interest while I was working at a nutrition/supplement store and I had a customer come in with Type 2 Diabetes (T2DM). I was almost finished with my undergrad and she asked me what I was in school for, we spoke about nutrition and she told me she was actually trying the Keto Diet. I was fascinated because I had always learned about the dangers of ketosis turning into Diabetic Ketoacidosis (DKA) for those with T2DM. She told me that she tested her ketone body levels in her urine daily. Monitoring ketone body levels is extremely important if you do choose to do Keto while diagnosed with T2DM.5


For reference: while following a normal diet with a balanced intake of macronutrients, your ketone body levels will be very low: less than 0.3mmol/L. The maximum amount of ketone bodies that can “safely” occur in those following a keto diet are 8mmol/L. Ketone bodies are being used for energy when the levels reach 4mmol/L. You can purchase strips to test your urine at home yourself if you’re curious!5


Studies have found that when those with T2DM adapt a ketogenic diet (correctly and safely) they see positive changes which include the following:5

  • A decreased HbA1c level.
  • It improves and can possibly reduce nephropathy due to the reduction in oxidative stress (as well as other forms of stress) and decreased creatinine.
  • It can improve renal function (renal is a fancy term for kidneys).
  • Due to the presence of ketone bodies, cardiac function can be improved and decrease the progression of heart failure.
  • It can decrease LDL and triglyceride levels, as well as increase in HDL levels (especially compared to a low-fat diet).

However, there are also a couple negative changes that may occur:5

  • If the person is taking an oral hypoglycemic medication while utilizing a ketogenic diet, they are at an extreme risk of developing hypoglycemia. Therefore, it’s important to discuss dietary changes with BOTH your MD and an RD.
  • For those who are prepping for bariatric surgeries, a keto diet is not ideal as the body is in an increased catabolic state as well as experiencing increased levels of oxidative stress post-surgery. This could cause negative outcomes as far as surgery goes.

Ketosis as Therapy for Epilepsy, Cancer, & More:

It’s common (very generalized) knowledge that a ketogenic diet can be used to treat epilepsy. Evidence shows that its therapeutic properties may be due to either: the direct anticonvulsant effects of ketone bodies and/or a pathway in the body that is way beyond the focus of this article. (For your googling pleasure, please see: rapamycin pathway). Keto diets show a 30-40% improvement in the occurrence of seizures and in children with epilepsy the keto diet has even more beneficial results.6

It is also well-known that a keto diet can be very effective in treating cancer. As some of you may or may not know, cancer has a unique link with CHO. The rates of glycolysis in cancer cells are insanely high. The relationship between insulin, CHO, and growing cancer cells begs the question: what if we take CHO away? Studies have shown that keto diets are capable of decreasing the size of cancer tumors as well as the progression of tumor growth. The most recent evidence is a study which shows that the absence of insulin due to the keto diet can help treat cancer. Basically: the lack of insulin in the cell due to a deficit of glucose to feed the cell ends up inhibiting cell growth. This is also why you may hear people say: “sugar feeds cancer”.6

A ketogenic diet can also help improve many different neurological issues such as brain trauma, Alzheimer’s, Parkinson’s, sleep disorders, autism, and multiple sclerosis. In Alzheimer’s, a ketogenic diet can help improve function in the mitochondria (ya know, the powerhouse of the cell). The diet can provide protective effects to neurons from the exposure to beta-amyloid via the ketone bodies and can also decrease oxidative stress. As for Parkinson’s, the same thing occurs with improvements in mitochondrial function but there needs to be more research done.6

Ketosis & Fitness:

I saved my favorite topic for last. My interest in sports nutrition (and fitness nutrition in general) is one fueled by passion. I see myself someday working with athletes, weightlifters, etc. So naturally, my interest in a ketogenic diet combined with any sort of physical activity and the results that this intervention emits is huge. It’s well-known that the ketogenic diet promotes weight loss due to the breakdown of fatty acids in the presence of ketone bodies.5,6


Several studies have shown that physical endurance is improved during ketosis. In studies of high-performance athletes, researchers found that ketosis increased intramuscular triacylglycerol oxidation during exercise (even when muscle glycogen was present). This means that the fat within skeletal muscle fibers was burned for energy during exercise. Ketosis has also been found to decrease the levels of plasma lactate and muscular glycolysis during exercise.7,8


In another study published this April, ketosis was also found to increase glucagon and cortisol levels long-term in ELITE, ULTRA-endurance athletes, this study ran for ~6 months. They also found that the rate of fat oxidation in these athletes increased an insane amount (more than twice the normal rate). The issue with this particular study was that it only consisted of 20 men (zero women) and once again I want to stress that this study was performed on elite, ultra-endurance athletes. This study was not done on the average Joe so please make your conclusions wisely. It is however, grounds for more studies like this to be performed, hopefully they will be longer term so we can gain more insight into ketosis as well as glucagon and cortisol’s relationships to adapting the body to ketosis.9


A more recent study published in May looked at the appetite regulation effects that ketosis may have on the body. During ketosis, many report feeling less hungry after a certain point but initially report having a crazy appetite. This study revealed that up to 3 weeks after beginning a ketogenic diet (or at 5% weight loss), appetite was increased. At 10-17% weight loss, there was no increased appetite. When refeeding occurred, hunger cues and active ghrelin increased.10


So, with all of this being said… Is the keto diet really this evil, horrible thing that everyone should stay away from? I doubt the people who say it isn’t beneficial have researched it. But also keep in mind that this diet should not just be done on a whim. If you’re planning on implementing this diet please for the love of the universe do it the right way. Go get some blood work done, make sure you’re healthy, talk to an RD, only do it in the short-term, etc. (If you DO insist on asking a “certified nutritionist” to plan this diet out for you: PLEASE make sure they either have experience with it or ask a knowledgeable friend to check the plan for you!)


I hope that y’all found this informative but not horribly painful because I honestly enjoyed writing about it. I am a nerd, sorry not sorry. Please leave comments with future blog suggestions and shoot me an email for nutrition coaching!


  1. Gropper, S. Smith, J. (2013) Advanced Nutrition & Human Metabolism. 6e. Cengage Learning.
  2. Low-carb diet: Can it help you lose weight? Mayo Clinic. (2014).
  3. Clifton, P., Condo, D., & Keogh, J. (2014). Long term weight maintenance after advice to consume low carbohydrate, higher protein diets – A systematic review and meta analysis. Nutrition, Metabolism and Cardiovascular Diseases, 24(3), 224-235. doi:10.1016/j.numecd.2013.11.006
  4. Johanne H. Ellenbroek, Laura V. Dijck, et al. (2014). Long-term ketogenic diet causes glucose intolerance and reduced β- and α-cell mass but no weight loss in mice. American Journal of Physiology – Endocrinology and Metabolism. Vol. 306 no. 5, E552-E558 DOI: 10.1152/ajpendo.00453.2013
  5. Azar ST. (2016) Benefits of Ketogenic Diet For Management of Type Two Diabetes: A Review. J Obes Eat Disord 2:2. doi: 10.21767/2471-8203.100022
  6. Paoli, A. Rubini, A. Et al (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition. 67, 789–796; doi:10.1038/ejcn.2013.116.
  7. Cox, P. Kirk, T. Et al (2016). Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes. Cell Metabolism. Volume 24, Issue 2, 9 August 2016, Pages 256-268.
  8. Egan, B. D’Agostino, D. (2016). Fueling Performance: Ketones Enter the Mix. Cell Metabolism. Volume 24, Issue 3, 13 September 2016, Pages 373-375.
  9. Miller, V. Hyde, P. Et al (2017). The Ketogenic Diet Alters Endocrine Regulation of Energy Metabolism in Ultra-Endurance Athletes. The FASEB Journal. vol. 31 no. 1 Supplement 1036.3.
  10. S Nymo, SR Coutinho, et al (2017). Timeline of changes in appetite during weight loss with a ketogenic diet. International Journal of Obesity. doi: 10.1038/ijo.2017.96