The side effects of a ketogenic diet aren’t bad if you understand why they happen and how to minimize them. Understanding any physical reactions you might have will help you avoid the worst of the symptoms and keep you from quitting before you can really get started.
After a few weeks, these low carb diet side effects will subside as you become “keto-adapted” and able to burn fat instead of glucose for fuel.
The list below includes the most common low carb diet side effects, and a few tips on how to mitigate them.
- Frequent Urination: After the first couple days, you may notice that you take trips to the washroom more frequently. This is caused by your body burning up the extra glycogen (stored glucose) in your liver and muscles. Breaking down glycogen releases a good amount of water. As your carbohydrate intake and glycogen levels drop, your kidneys will need to dump the excess water.
Additionally, as your circulating insulin levels drop, your kidneys start excreting excess sodium, which will also cause more frequent urination. (see this reference).
- Fatigue and Headaches/Dizziness: As you start losing water weight, you’ll also lose minerals such as sodium, potassium and magnesium. Having lower levels of these minerals will make you very tired, lightheaded or possibly dizzy. You could also experience some muscle cramps and/or headaches. This is one of the most common of the low carb ketogenic diet side effects, and it can be avoided for the most part by ensuring that you replace enough of the minerals which are being lost. If you experience this, it usually only lasts for about 3-4 days.
You can do this by eating more salt in your meals, and eating foods which are rich in potassium. (Bananas and avocados are both great sources of potassium).
As long as your carb intake is below 60 grams per day, you’ll need to continue to eat a moderate amount of salt – roughly 5 grams/day. This is about the same as the standard American diet provides. However, if you are on high blood pressure medication, check with your doctor before taking this step.
It’s also very important to eat at least 2 cups of raw green leafy vegetables every day. These vegetables provide potassium and vitamin K, and will also obviously help with hunger!
- Reactive Hypoglycemia: If you’ve been eating a higher carbohydrate diet, your body is acclimated to producing a certain amount of insulin to be able to process all of the sugar which gets created from that high carbohydrate intake.
When you suddenly drop your carb intake on a ketogenic diet plan, you may experience some transient low blood sugar episodes that can feel scary. Rest assured this won’t last, and is simply your body adjusting to a healthier diet.
- Shakiness or weakness: this is a side effect of hypoglycemia or low blood sugar. It could also be a symptom of low mineral levels. Try adding some more protein to your daily diet to counter the drop in blood sugar, and eat more salt and potassium containing foods. You might also try taking a 100 mg potassium citrate supplement.
- Sugar Cravings: As your body goes through the process of revamping itself to burn fat instead of sugar, there’s an approximately 2-5 day transitional period in which carb cravings will be worse. If you can wait it out, the cravings will subside and eventually disappear, as long as you don’t cheat!
- Diarrhea: This usually happens to people who unwisely decide to also limit their fat intake on a low carb diet, which results in eating too much protein. Eating a high protein, low carb AND low fat diet will cause symptoms of “rabbit starvation“. Make sure you replace the carbs you are cutting with fat, ideally saturated fat such as butter or coconut oil. Following a ketogenic diet menu means you can choose fattier cuts of meat, whole milk and use heavier coffee cream.
- Muscle Cramps: This is another side effect of the loss of minerals, specifically magnesium. In their excellent book The Art and Science of Low Carbohydrate Living: An Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable, Drs. Jeff Volek and Stephen Phinney recommend taking 3 slow release magnesium tablets such as Slow-Mag or Mag 64 for 20 days, then continuing to take 1 tablet per day afterwards. Again, if you have kidney problems, don’t take oral magnesium supplements without first checking with your doctor.
- Constipation: This is another one of the most common low carb diet side effects, and is usually caused by a magnesium deficiency. It’s been shown that taking 400 mg of magnesium citrate every night before bed can help. If the magnesium citrate isn’t helping, you may want to cut back on your dairy product consumption. (If you have kidney or heart health issues, check with your doctor first.)
Also, I’ve found that eating cheese on a daily basis to be a factor in this side effect. If I avoid cheese, or at least limit my cheese intake to less than 1 ounce per day, I find that my entire system just seems to perform more normally. You could also add another 100 mg of magnesium to your daily intake, but don’t go overboard. Magnesium is powerful stuff, and you don’t want to take too much. You’ll know if you have because you’ll spend the day in the bathroom.