Here are a few of the most common side effects that I come across when people first start keto. Frequently the issues relate to dehydration or lack of micronutrients (vitamins) in the body. Make sure that you’re drinking enough water (close to a gallon a day) and eating foods with good sources of micronutrients. To read more on micronutrients, click here >
The bottom line is that there have not been enough scientific studies, especially longer term ones, to really determine all the potential risks and benefits of the keto diet. Many of the claims out there on the Internet, social media, or television in either direction are anecdotal, meaning that they are individuals telling stories about what has supposedly been their experiences. Take everything you hear that is not supported by scientific evidence with a grain of salt (but not too much salt because too much can be bad for you.)
Normal dietary fat contains mostly long-chain triglycerides (LCTs). Medium-chain triglycerides (MCTs) are more ketogenic than LCTs because they generate more ketones per unit of energy when metabolised. Their use allows for a diet with a lower proportion of fat and a greater proportion of protein and carbohydrate,[18] leading to more food choices and larger portion sizes.[4] The original MCT diet developed by Peter Huttenlocher in the 1970s derived 60% of its calories from MCT oil.[15] Consuming that quantity of MCT oil caused abdominal cramps, diarrhea, and vomiting in some children. A figure of 45% is regarded as a balance between achieving good ketosis and minimising gastrointestinal complaints. The classical and modified MCT ketogenic diets are equally effective and differences in tolerability are not statistically significant.[9] The MCT diet is less popular in the United States; MCT oil is more expensive than other dietary fats and is not covered by insurance companies.[18]
I’ve been on and off of my Keto diet with the primary purpose of losing weight. I’m 30 years old, workout daily – I’m in decent shape but have some extra fat around the mid-section that I’d like to get rid of, I am hoping to lose ~20 pounds of fat. However, the problem is that I am an extremely picky eater with tremendous cravings for some of my favorite carb-heavy foods – I only eat a number of high-fat / low-carb foods that help me attain Ketosis, so cycling through them multiple times a week becomes excruciating. I find myself cheating on my diet every 2 – 3 weeks, which causes a 3 – 5 pound setback that takes me a few days to overcome and get back into ketosis.
Hi, I am a parent of son with epilepsy. On our last EEG we found out he is having 10 absence seizures per hour as well as bimonthly grandmal seizures . People have been using the ketogenic diet for seizure control for years. Our neurologist mentioned that seizure control is effected by blood insulin as well as ketones. I know the original Keto esters came from DR. D’Augustino’s work with Navy Seals who were having seizures due oxygen toxicity. The main reason we have not been using the Keto diet is lack of compliance and it so easy for kids to get out of ketosis. I am wondering if we could get seizure control with a zonish/adkins diet with keto os, brain octain supplementation. Even an educated guess would be appreciated. Thanks, Mike
This is an absolutely necessary function for basic survival. As the body can only store carbs for a day or two, the brain would quickly shut down after a couple of days without food. Alternatively it would quickly have to convert our muscle protein into glucose – a very inefficient process – just to keep the brain going. That would make us waste away quickly. It would also ensure that the human race could hardly have survived all those millennia before we had 24-7 food availability.
I just discovered your site and have been thoroughly enjoying many of the articles and appreciate that you get so in depth in your explanations. I’m in my late 40’s and, while not an extreme endurance athlete, I am moderately active with 18-20 mile rides 3x a week as well as some boxing and body weight resistance (push up, pull up, etc) mixed in. I’ve generally been paleo and stick to quality macros for the most part (grass fed meats/dairy, organic veg and oils) and zero supplements. I recently started following keto (after reading this article) about 10 days ago and things seem good thus far. I do, however, want to avoid any of the negative side effects you mention and also not lose any lean muscle. I’m currently about 174 lbs, 5’8″ and about 19% bodyfat – I’m taking in about 95g protein, 130g fat and <20g net carbs. I'm eating all quality – wild salmon, grass fed beef, pastured eggs, coconut oil, Brain Octane and Grass fed butter in coffee, sardines, etc. With a smattering of organic veg, but it seems real easy to bust through the carb barrier. *I'M ALSO TAKING KETOCANA PRE-WORKOUT* and I notice this is keeping me going throughout a ride or the gym.
Apparently, Dominic’s research seems to be suggesting the fact that diet-induced ketosis from a high-fat, low-carb intake, especially when combined with the use of nutrition supplements such as powdered ketones or MCT oil, can vastly reduce the need for the brain to use oxygen to burn glucose. This is because the brain can use up to around 75% of its fuel from ketones. So a ketone-fed or a fat-adapted brain can be better equipped to withstand low oxygen availability and potentially support longer breath-hold times. Dominic’s research also shows that in the presence of ketosis, the brain and body are able to resist the potential cell damage of long periods of time with low oxygen, also known as “hypoperfusion”.
Intermittent fasting is another way to achieve ketosis. This doesn’t suggest going days without food, but rather intermittent fasting. You can eat for eight hours and then fast for 16 hours, or eat a low-calorie diet for a few days (about 1,200 daily calories if you’re a woman and 1,500 daily calories if you’re a man). As you take in less food, your body uses more of its fat stores for fuel.
“When you start the keto diet, you lose sodium and other electrolytes in the urine due to reductions in insulin,” says Yawitz. “This is a major contributor to symptoms of keto flu.” So it’s important to replenish sodium through the diet, especially if you exercise or sweat a lot. “This can help ward off more serious side effects that are seen with long-term sodium deficiencies,” says Yawitz. These include lethargy and confusion — and in extreme cases, seizures, coma, and death, according to the Mayo Clinic.
The Keto diet emphasizes weight loss through fat-burning. The goal is to quickly lose weight and ultimately feel fuller with fewer cravings, while boosting your mood, mental focus and energy. According to Keto proponents, by slashing the carbs you consume and instead filling up on fats, you safely enter a state of ketosis. That’s when the body breaks down both dietary and stored body fat into substances called ketones. Your fat-burning system now relies mainly on fat – instead of sugar – for energy. While similar in some ways to familiar low-carb diets, the Keto diet’s extreme carb restrictions – about 20 net carbs a day or less, depending on the version – and the deliberate shift into ketosis are what set this increasingly popular diet apart.

Then there’s medium chain triglycerides (MCT’s). Most dietary fat has to be converted into water soluble molecules that then need to enter the liver via your lymph system. Your liver then converts these molecules to fatty acids and ketone bodies. But unlike most other forms of dietary fats, MCT’s can enter your liver directly without having to go through your lymph system. This means that consuming MCT’s gives your body an opportunity to quickly produce ketone bodies.
-Pancreatic Dysfunction: The beta cells in the pancreas that produce the insulin to help control blood sugar become dysfunctional with high blood glucose, raising the risk for type 2 diabetes. Researchers have discovered that beta cell issues are detectable in people whose glucose levels spike two hours after eating, despite those levels staying within the range considered normal and safe by the medical establishment.
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