Keto Diet vs Intermittent Fasting: What's the Difference? (2023)

The keto diet and intermittent fasting are both extremely hot topics right now in the natural health community. 'Intermittent fasting' exceeds the 'keto diet' in popularity with being the top Google searched and tested method in 2019.

Keto and intermittent fasting aren’t so different, from a metabolic perspective. Essentially, both programs help you transition toward burning fat for energy, rather than a store-full of glycogen. This is a good place to be in for weight loss, body recomposition, and several other health benefits.

Intermittent Fasting

Intermittent fasting is currently one of the most popular nutrition programs around. Unlike diets that tell you what to eat, intermittent fasting focuses on when to eat.

Limiting the hours you eat each day may help you consume fewer calories. It may also provide health benefits, including weight loss and improved heart health and blood sugar levels.

There are several forms of intermittent fasting, including a common form called time-restricted eating.

Research overwhelmingly supports the notion that ditching the three square meals a day approach in favor of time-restricted feeding — can do wonders for your health. Contrary to modern belief, your body isn't designed to be fed throughout the day, and the near-continuous grazing that most engage in can have serious health consequences.

The main “varieties” of intermittent fasting are:

• 12/12. A 12 hour daily overnight fast.
• 16/8: 16 hours of fasting, 8 hours of feeding.
• OMAD: One meal a day.
• 5:2: 2 non-consecutive days of modified fasting per week.
• ADF: Alternate day fasting.
• TRE: Time restricted eating

Keto Diet

There isn't a buzzier diet right now than the keto diet. A keto diet is well known for being a low carb diet, where the body produces ketones in the liver to be used as energy. It’s referred to as many different names – ketogenic diet, low carb diet, low carb high fat (LCHF), etc.

In fact, many studies show that keto diet can help you lose weight and improve your health (Source). Ketogenic diets may even have benefits against diabetes, cancer, epilepsy and Alzheimer’s disease (Source, Source, Source, Source).

There are more than 400 publications related to keto diet and mental illness, indexed on PubMed.

Research also shows the ketogenic diet can help human bodies stay underwater for longer periods of time, according to The Washington Times.

Credit: Nick Norwitz (Twitter)

Keto basics

The ketogenic diet is a very low carb, high fat diet that shares many similarities with the Atkins and low carb diets.

It involves drastically reducing carbohydrate intake and replacing it with fat. This reduction in carbs puts your body into a metabolic state called ketosis.

When this happens, your body becomes incredibly efficient at burning fat for energy. It also turns fat into ketones in the liver, which can supply energy for the brain (Source).

Ketogenic diets can cause significant reductions in blood sugar and insulin levels. This, along with the increased ketones, has some health benefits (Trusted Source, Trusted Source, Trusted Source).

Different types of ketogenic diets

There are several versions of the ketogenic diet, including:

• Standard ketogenic diet (SKD): This is a very low carb, moderate protein and high fat diet. It typically contains 70% fat, 20% protein, and only 10% carbs (Trusted Source).
• Cyclical ketogenic diet (CKD): This diet involves periods of higher carb refeeds, such as 5 ketogenic days followed by 2 high carb days.
• Targeted ketogenic diet (TKD): This diet allows you to add carbs around workouts.
• High protein ketogenic diet: This is similar to a standard ketogenic diet, but includes more protein. The ratio is often 60% fat, 35% protein, and 5% carbs.

However, only the standard and high protein ketogenic diets have been studied extensively. Cyclical or targeted ketogenic diets are more advanced methods and primarily used by bodybuilders or athletes.

The information in this article mostly applies to the standard ketogenic diet (SKD), although many of the same principles also apply to the other versions.

Foods to avoid

Any food that’s high in carbs should be limited.

Here’s a list of foods that need to be reduced or eliminated on a ketogenic diet:

• sugary foods: soda, fruit juice, smoothies, cake, ice cream, candy, etc.
• grains or starches: wheat-based products, rice, pasta, cereal, etc.
• fruit: all fruit, except small portions of berries like strawberries
• beans or legumes: peas, kidney beans, lentils, chickpeas, etc.
• root vegetables and tubers: potatoes, sweet potatoes, carrots, parsnips, etc.
• low fat or diet products: low fat mayonnaise, salad dressings, and condiments
• some condiments or sauces: barbecue sauce, honey mustard, teriyaki sauce, ketchup, etc.
• unhealthy fats: processed vegetable oils, mayonnaise, etc.
• alcohol: beer, wine, liquor, mixed drinks
• sugar-free diet foods: sugar-free candies, syrups, puddings, sweeteners, desserts, etc.

Foods to eat

You should base the majority of your meals around these foods:

• meat: red meat, steak, ham, sausage, bacon, chicken, and turkey
• fatty fish: salmon, trout, tuna, and mackerel
• eggs: pastured or omega-3 whole eggs
• butter and cream: grass-fed butter and heavy cream
• cheese: unprocessed cheeses like cheddar, goat, cream, blue, or mozzarella
• nuts and seeds: almonds, walnuts, flaxseeds, pumpkin seeds, chia seeds, etc.
• healthy oils: extra virgin olive oil, coconut oil, and avocado oil
• avocados: whole avocados or freshly made guacamole
• low carb veggies: green veggies, tomatoes, onions, peppers, etc.
• condiments: salt, pepper, herbs, and spices

Risks of the keto diet

Staying on the keto diet in the long term may have some negative effects, including risks of the following:

• low protein in the blood
• extra fat in the liver
• kidney stones
• micronutrient deficiencies

Important Safety Note: A strict ketogenic diet might cause liver failure due to the omega-6 fats in the diet. It's crucial to make sure the fats you eat are actually healthy. For details, check out "

How Linoleic Acid Wrecks Your Health".

Diabetic Ketoacidosis vs Ketosis

Diabetic ketoacidosis (DKA) is a serious complication of type 1 diabetes and, much less commonly, of type 2 diabetes. DKA happens when your blood sugar is very high and acidic substances called ketones build up to dangerous levels in your body.

Ketoacidosis shouldn’t be confused with ketosis, which is harmless. Ketosis can occur as a result of an extremely low carbohydrate diet, known as a ketogenic diet, or from fasting.

DKA only happens when you don’t have enough insulin in your body to process blood sugar into energy. If this happens, your liver starts to process fat into energy, which releases ketones into the blood. High levels of ketones in the blood are dangerous.

DKA is a medical emergency. Call your local emergency services immediately if you think you may be experiencing DKA.

If left untreated, DKA can lead to a coma or death.

More research is being done to determine the safety of the keto diet in the long term. Keep your doctor informed of your eating plan to guide your choices.

KETO INTERMITTENT FASTING CHALLENGES AND SOLUTIONS

Combining the two diets is pretty simple. You simply need to eat keto based meals during the eating windows. 

However, keto and fasting come with overlapping sets of obstacles. Here are some of the biggest areas that might trip people up.

CHALLENGE #1: HUNGER

When you fast—even intermittently—hunger is inevitable. Some worry, however, that the cravings will become so unbearable that you’ll end up snacking on your arm.

The first thing to realize is that hunger is natural. Dizziness or lightheadedness is not, but hunger is.

Second, hunger ebbs and flows. It doesn’t spiral upwards to infinity, but rather stabilizes over time.

What You Can Do: Go Keto First. This hunger-control benefit is another reason why these regimens work so nicely together. Going keto first helps you better access body fat for energy. 

CHALLENGE #2: KETO FLU

Most people don’t consume enough electrolytes. Period. But on a keto diet or intermittent fasting regimen, the potential for deficiency is magnified.

That’s because a low insulin state (due to carb restriction) makes you excrete more sodium and fluids through urine. If these aren’t replaced, you’ll end up dehydrated and electrolyte deficient.

The resulting cluster of symptoms—headaches, fatigue, weakness, cramps, etc.—are often called keto flu. Luckily, it’s an easy fix.

What You Can Do: Drink Electrolyte Water. We recommend taking 5000 mg sodium, 1000 mg potassium, and 200 mg magnesium on top of food sources. Consume these electrolytes with fluids to keep your energy up and prevent keto flu symptoms—also, spread them out! I wouldn’t down all that at once unless you enjoy disaster pants.

CHALLENGE #3: SLEEP ISSUES

Many folks have trouble going to bed hungry, and it’s not just a psychological quirk. In fact, fasting increases alertness chemicals like adrenaline and orexin-A that can make relaxation difficult.

What You Can Do: Back Off The Fasting. If you can’t sleep, consider backing off to an easier fasting regimen. For example, step down to 16/8 from ADF. The benefits of fasting probably don’t outweigh the harms of sleep deprivation. When in doubt, listen to your body!

CHALLENGE #4: DIGESTION

When you shift to a keto diet, your gut bacteria shift too. This can cause changes in digestion, often resulting in constipation and diarrhea.

What You Can Do: Play With Fiber. Try increasing your intake of non-starchy vegetables. This extra fiber should keep your gut bugs happy and move things along down there. Keep in mind, however, that increasing fiber isn’t always the solution for gut issues. In fact, low fiber diets have been shown to be effective in reducing IBS symptoms. You’ll have to experiment to see what works best.

CHALLENGE #5: MUSCLE MAINTENANCE

To build muscle requires resistance training, a caloric surplus, and adequate protein. On keto and fasting regimens, people often fall short on the final two criteria.

Let’s zoom in on the protein goal. Along with insufficient electrolytes, insufficient protein is one of the main mistakes folks make on keto. Why? Because people take “high-fat” to mean a plate full of fat, with some protein on the side. But since fat contains 9 calories a gram, and protein only 4, your plate should actually be centered around protein.

What You Can Do: Bump Up Protein. To gain or maintain muscle, shoot for about 1 gram protein per pound of lean mass.

What You Can Do: Shorter Fasts. Lean towards shorter fasts (12 to 16 hours) to ensure adequate calories. These calories provide the raw materials required to build muscle.