Pitfalls of the Keto Diet and How Carb Cycling Can Help

By: Courtney Sperlazza, MPH
November 27, 2019

Pitfalls of the Keto Diet and How Carb Cycling Can Help

  • On the keto diet, you get most of your calories from fat, moderate calories from protein and very few from carbohydrates. This combination puts you in a fat-burning state called ketosis.
  • Some people can run into problems when they restrict carbohydrates long-term, like persistent flu-like symptoms, dry eyes and fatigue. Talk to your doctor if you’re dealing with keto flu symptoms that last over two weeks.
  • If your body is asking for more carbs, you have options. When you’re carb cycling, you eat slightly more carbs one day per week. Other styles of keto diet give you more flexibility with your net carb total.
  • Get all the details about carb cycling and find out why the Bulletproof Diet is a cyclical keto diet.

What you eat on the keto diet can vary, depending on who you ask.

Generally, it means getting most of your calories from fat, moderate calories from protein and very few from carbohydrates. The exact ratio of fat, protein and carbs can vary (more on that below). This combination puts you in ketosis, a powerful way to burn body fat and dial in your mental focus, among other keto benefits.

But before you cut out all of your carbohydrates, you need to know a few things. The full keto diet isn’t perfect for everyone, and you may need to tweak it a little, depending on your individual biology.

Keep reading to find out what snags you could run into while in ketosis, and what variations might work better with your system. And remember, it’s a good idea to see your doctor before making any major dietary changes.

Downsides to the keto diet

The first two weeks

When you first venture into cutting carbs and entering ketosis, you start what’s known as the “keto flu,” the period during which your body shifts from burning carbs and sugar for energy to burning fat. It takes anywhere from a few days to about two weeks for your metabolism to re-regulate the way it uses food and generates energy.

Whether you call it keto flu, carb flu, carb withdrawal or sugar crash, what you’re feeling is real. You’ll experience some combination of these symptoms:

  • Insomnia
  • Irritability
  • Muscle soreness
  • Nausea
  • Poor focus
  • Stomach pains
  • Sugar cravings
  • Brain fog
  • Headache
  • Chills
  • Sore throat
  • Confusion
  • Dizziness
  • Dry eyes
  • Signs of hormone imbalance
  • Signs of adrenal issues
  • Aches and pains

Your symptoms of carb restriction should be temporary. Once your body fully adjusts to burning fat instead of sugar and carbs, you should feel better than you did before you started. If your symptoms persist, see your doctor.

Beyond the two-week mark

Person covered with gray blanket in bed

Your body will tell you if you’ve gone overboard with restricting carbs, or if you’ve gone too low for too long. Some of the negative symptoms of ketosis may include:

  • Dry eyes: Carbs help your mucus membranes produce the mucus that lines your gut and nasal passages and keeps your eyes hydrated. Some people notice that after restricting carbs long-term (50 grams per day or less), their eyes become irritated. This is a sign that other necessary mucus membranes aren’t working as well as they could be.
  • Hormonal imbalances: Severe long-term carb restriction can cause your T3 thyroid hormone to drop. [1] [2] That’s a big deal because thyroid hormones control the way your body uses energy, so they can affect nearly every organ in your body.[3]
  • Fatigue: Burning fat for fuel doesn’t work for everyone. In many people, burning fat for fuel ramps up the hypothalamic-pituitary-adrenal (HPA) axis, which gives you more energy.[4] But in some people, long-term carb restriction stresses the HPA axis, which makes you feel tired all the time.

If you experience these symptoms, you don’t have to give up keto entirely. You can enjoy the amazing benefits you keep hearing about with some slight modifications.

Namely, you may want to add back in some carbohydrates, or experiment with a cyclical ketogenic diet.

How many carbs on keto?

Sweet potatoes on orange background

A good rule of thumb is 50 grams of carbs per day, but it’s your results may vary, depending on your diet and individual biology. If you’re still experiencing flu-like symptoms after the two week mark, your body might be asking for more carbs.

For example, if you’re super active, you might need more than 50 grams of carbs per day. And if you’re hitting 50 grams per day, but not factoring in net carbs (aka your total carbs minus fiber and sugar alcohols), you might need to raise your daily carb intake.

Related: How to Find Your Ideal Carb Intake

How to increase your overall carb intake on keto

Butternut squash pasta with bacon and sage

Keep reading to learn about different ways to eat more carbs on keto without missing out on the benefits of ketosis.

Remember, if you’re going to increase your carb intake, track yourself to see how your body responds. When you’re experimenting with your carb intake, ketone breath meters and keto sticks are great ways to see if you’re actually in ketosis.

Carb cycling

Raspberries in cartons

On keto, carb cycling is also called cyclical ketosis. It’s already built into the Bulletproof Diet.

When you’re carb cycling, you pick one day per week to eat more high-quality carbs (approximately 150 grams of net carbs). On your carb refeed day, you can add things like:

  • Sweet potato
  • White rice
  • Butternut squash
  • Carrots
  • Plantains
  • Low-sugar berries

You might temporarily dip out of ketosis on your higher-carb day, but once your body burns through those extra carbs, you’ll return to ketosis. (This is called metabolic flexibility.)

Carb cycling this way allows you to take advantage of all the keto benefits, like appetite suppression, fat burning, boundless energy and laser focus, while still getting the carbs your body systems need to function properly.

Experiment with exogenous ketones

Scoop with exogenous ketones on blue background

When you’re in ketosis, your body produces an alternative form of fuel called ketones. You can also supplement with exogenous ketones, which are ketones you ingest. Exogenous ketones can boost your ketone levels, which helps you stay in ketosis, even when you have some carbs in your system.

Here are two types of exogenous ketones — and important details to keep in mind.

  • Ketone salts: Not all of the ketones in ketone salts are bioidentical, which means the body may not be able to use them. Learn why you can skip most ketone salts.
  • Ketone esters: Ketone esters are more effective than ketone salts, but they taste like something you would find in a hospital antiseptic closet. Plus, they’re expensive to buy and not widely available for purchase.

Brain Octane MCT oil is the happy medium between pure nutritional ketosis and exogenous ketones. It’s pure C8 MCT oil, aka the most ketogenic MCT, and it raises ketone levels four times more efficiently than coconut oil alone. That means more brain-powering, fat-burning keto benefits — and you can add it to anything, like coffee and salad dressings.

Related: Everything You Want to Know About Bulletproof MCT oils

Other types of keto diets

Three jumbo shrimp on zucchini noodles with lime

You aren’t limited to one style of eating on the keto diet. There are different variations that can help you stay in the fat-burning state of ketosis, while still increasing your carb intake.

  • Targeted keto is great for athletes because you eat more carbs before you work out — that way, your muscles will have glucose available to power through your gym session.
  • On the moderate keto diet, you eat 100 to 150 grams of net carbs per day.
  • Read more about the different types of keto diets.

The keto diet can totally work long-term, but there are instances where you may need need to modify it just a little to get the maximum lasting benefit — and that’s perfectly okay. In fact, that makes you even more Bulletproof because you’re listening to your body and finding what works for you and your goals.

Related: 7 Reasons You’re Not Losing Weight on Keto

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