The Keto Diet Explained

So, what exactly is the ketogenic, or “keto,” diet? 

A ketogenic diet is a way of eating that will shift your metabolism from primarily burning glucose (from carbs) as fuel to burning fat in the form of ketones instead. Ketones, by the way, are energy molecules that your body produces when it breaks down fat from your fat stores. When you make this metabolic switch, you enter a state called “ketosis.”

In order to switch over into ketosis (“fat-burning mode”), you must restrict your carbohydrate intake enough to signal your body that it needs to look for alternative fuel sources. Once this happens, your body starts to tap into your fat stores for fuel, and the production of ketones begins.

Although the ketogenic diet trend has caught on more recently, this way of eating is actually nothing new. In fact, about 100 years ago, the keto diet was developed to help children with epilepsy control their seizures. Since then, different takes on low-carb diets have come out, with the most popular being the Atkins Diet. 

One primary difference between the Atkins approach to low-carb versus keto, however, is the intention behind the diet. Where Atkins was all about cutting carbs for quick weight loss, keto diet enthusiasts speak about it as a lifestyle as opposed to a quick fix. You can certainly use keto to drop a few pounds quickly, but unless you follow this diet for an extended period of time, the pounds will likely come back. 

Using keto as a lifestyle change can deliver pretty impressive health benefits for some people. This is especially true if you follow a “clean” keto diet as opposed to a “dirty” keto diet (more on that below). For now, though, let’s stick to the basic tenets. 

A ketogenic diet is low in carbohydrates, high in fat, and contains a moderate amount of protein. Although the exact ratio will differ for everyone, the standard guideline for macronutrient intake, to begin with, is:

• 55–60% fat
• 30–35% protein
• 5–10% carbohydrates

How exactly does this work? While there are apps that can help you track the number of carbs, fat, and protein you eat every day, most people prefer to just cut carbohydrates down to 50 grams per day or less, as this is typically all it takes to get into ketosis. 

How Do You Count Carbs?

Counting carbs is pretty simple as long as you know where to look. For any packaged food, there will be a nutrition label that states exactly how many carbohydrates the food contains per serving. Make sure that when you count your carbs, you’re also accounting for the serving size.

For instance, if you notice that a protein bar has five grams of carbs per serving, but the serving size of the entire bar is two servings, you have to double the carbs. 

Another aspect of carb counting to be aware of is net carbs. Net carbs are the total amount of carbohydrates in a food minus the dietary fiber. Since dietary fiber isn’t absorbed but is typically counted towards the total carbohydrates, you have to subtract the fiber content in order to get the correct carb count. This accuracy is important for getting into ketosis. 

Some people find that they need to cut carbs further than 50 grams per day to achieve ketosis, but 50 grams will work for most individuals.

Once in the ketogenic state, however, positive changes can take place, from subtle to dramatic.

Weight Loss

One of the benefits that drives many people to try the keto diet is its ability to assist in weight loss.

Research shows that following a low-carb, ketogenic diet is more effective than calorie restriction or low-fat dieting, especially in the beginning stages of weight loss.

The reason for this is twofold. On one hand, being in ketosis can naturally reduce the number of calories you consume daily. Reducing carbohydrates limits your body’s reliance on insulin, cutting sugar cravings. Meanwhile, ketones provide a satiating effect so that you’re not as hungry as you would be if you were running on glucose. This often results in lower calorie consumption. 

Ketosis also increases fat burning, which means that when your body needs to tap into its energy stores, you don’t have to work through glucose first. You start pulling energy directly from your fat stores. 

Improved Cognitive Health

As mentioned, the ketogenic diet was originally created in the 1920s as a way to help treat children with epilepsy. It turns out that when your brain relies on ketones for energy, there’s an anti-inflammatory effect, which for many epileptic children resulted in fewer seizures. 

Today, researchers have used the ketogenic diet as a potential anti-inflammatory approach to neurological diseases like Alzheimer’s and Parkinson’s with great success in both animal and clinical settings.

With outcomes like improved memory, improved social behavior, and enhanced neuroprotection, the ketogenic diet is quickly becoming one of the most well-researched approaches to prevention and treatment of age-related cognitive decline.

Blood Sugar and Insulin Resistance

The ketogenic diet may support people with diabetes and prediabetes. The move from glucose to ketones eliminates the blood sugar roller coaster that many diabetics have to manage daily. 

In one study, researchers compared the blood sugar and insulin control in two groups of people with diabetes. One group followed a low-carb ketogenic diet, while the other group followed a low-glycemic, low-calorie diet. While both interventions led to improvements in blood sugar and insulin levels, the ketogenic group saw significant changes that led 95% of the participants to reduce or eliminate their diabetes medications. 

Improves Risk Factors for Heart Disease

A common misconception of the ketogenic diet is that it will lead to heart disease. This is based primarily on some outdated studies that correlated saturated fat with cardiovascular disease, which have now largely been scrutinized due to insufficient data.

Interestingly, research on the ketogenic diet and heart disease show some promising results regarding the positive impact of low-carb, high-fat dieting on several risk factors. 

More recent evidence shows that following a ketogenic diet may:

• Decrease LDL cholesterol (the bad kind which contributes to plaques in your arteries) while increasing HDL cholesterol (the good kind that protects your heart).
• Regulate blood sugar, which when unmanaged, can contribute to damage to your blood vessels.
• Lower serum triglycerides, which can contribute to hardening your arteries. 
• Reduce weight, which is related to all the above risk factors. 

May Have Cancer-Protective Qualities

There have been numerous preclinical studies that support the use of a ketogenic diet for cancer treatment due primarily to the fact that cancer cells seem to require glucose for fuel. Research shows that when cancer cells lack the ability to use glucose as fuel, they starve since ketones don’t feed these specific cell lines.

Furthermore, when glucose is scarce, levels of insulin and insulin-like growth factor—two important drivers for cancer cell proliferation—are shown to drop. 

More clinical studies need to be conducted to validate these claims in humans, but the research suggests there is a positive effect. 

May Protect Against Metabolic Syndrome 

Metabolic syndrome is a cluster of health conditions that increase your risk for heart disease, stroke, and type 2 diabetes. 

These conditions include:

• Increased blood pressure
• High blood sugar
• Excess body fat around the waist
• High LDL cholesterol
• Abnormal serum triglycerides 

Unfortunately, research shows that about 24% of the US adult population is affected by metabolic syndrome, and that number only seems to be growing. 

As previously shown, the ketogenic diet controls for almost all of these risk factors, making it an excellent choice if you’re worried about metabolic syndrome or the individual health conditions that may cause it.

Over the past few years, people have modified the keto diet to make it work for different lifestyles. Specifically, the “targeted” and “cyclical” keto diet may be helpful if you’re an athlete or are working on specific physical goals. 

Here is a breakdown of the three most popular versions of the ketogenic diet.

Standard Keto Diet (SKD)

So far, the standard keto diet is the framework we’ve been discussing. With the SKD, you’ll drastically reduce your carbohydrate intake to 50 grams per day or less while focusing on healthy fats and protein. 

The SKD is the version of the keto diet that most must begin with in order to become keto-adapted and enter a state of ketosis. There isn’t much modification that goes on with the SKD; you just keep carbs low and stay in ketosis long term without elevating your blood sugar. 

Targeted Keto Diet (TKD)

The targeted keto diet is meant for athletes and high-performers who could benefit from targeted times of higher carb intake. It should be noted that this way of eating isn’t meant for the average person who works out at a moderate intensity. Instead, it’s ideal for those who train at high intensities for extended periods of time. 

When you follow a TKD, you’ll consume carbs only around your exercise periods. This allows you to get the blood sugar rush from carbs and then immediately burn through it as you exercise. Therefore, in theory, you should only be out of ketosis for a short period of time. 

When following a TKD, you’ll also want to pay attention to the number of carbs that you consume. If you overdo it, you may not burn up enough to get yourself back into ketosis quickly, so there is some trial and error that must take place with this version.

Cyclical Keto Diet (CKD)

The cyclical keto diet is another modification that involves increasing carb intake. With CKD, instead of only dipping out of ketosis for a short period (as in the TKD), you transition out of keto for a day or two per week. 

This is a great option if you’re looking to replenish your carbohydrate stores to really hit the gym hard or go for an intense endurance workout. It’s also helpful for those that want to increase their muscle mass. 

Typically, a CKD would involve five or six days a week of SKD, with one or two days of “refeeding,” where you consume large amounts of carbohydrates. The general ratio of macronutrients for refeeding days is:

• 60–70% of your total calories from carbs
• 15–20% of your total calories from protein
• 5–10% of your total calories from fat

This type of diet should only be followed if your body has already gotten to the point of metabolic flexibility, where you can go back and forth from burning fat for fuel to burning glucose pretty easily. For most people, to reach metabolic flexibility, it takes at least a few months of strict keto.  

Dirty vs. Clean Keto

Before we jump into the food lists, it’s essential to address the difference between what’s considered “dirty keto” and what’s considered “clean keto.”

If you look at the keto diet purely from a biochemical perspective, then the only requirement for food would be that it was low enough in carbs to get you into ketosis and keep you in that state. With that being said, the ketogenic lifestyle is about much more than simply running on ketones. Keto enthusiasts look at ketosis as a way of life, where you’re fueling your body with high-quality foods that will nourish you on a cellular level. 

Some people jump into the diet in a somewhat “Atkins-style” approach, where the only guidelines are to keep carbs low and fat and protein high. This often results in meal plans loaded with processed meats, low-quality fat, and a scant amount of vegetables. This “dirty keto” approach may help you shed some pounds in the short term, but low-quality food will not nourish your body in the long run. 

Therefore, if you want to reap all the benefits of a keto diet, quality must be top of mind. 

What does quality look like? Here is a little breakdown on food designations to seek out:

Animal Products

• Organic
• Grass-fed
• Hormone-free
• Antibiotic-free
• Free-range

Plant Foods

• Organic
• Non-GMO

Packaged Foods

• Not highly processed
• Real food ingredients (whole foods)
• No chemicals that you can’t pronounce
• No artificial sweeteners

Keto-Friendly Food List

Protein

• Beef 
• Elk
• Deer
• Pork
• Chicken
• Turkey
• Lamb
• Bison
• Veal
• Duck
• Eggs
• Salmon
• Mackerel
• Tuna
• Swordfish
• Mahi-mahi
• Trout
• Snapper
• Shellfish
• Sole
• Cod
• Sardines

Dairy/Eggs

• Whey protein
• Eggs
• Cottage cheese
• Full-fat greek yogurt
• Butter 

Fat

• Butter
• Lard
• Ghee
• Olive oil
• Sesame oil
• Almond oil
• Avocado oil
• Coconut oil 
• Coconut cream

Nut and Seeds

• Almonds
• Walnuts
• Macadamias
• Brazil nuts
• Pistachios 
• Cashews
• Hazelnuts 
• Pecans
• Pine nuts
• Pumpkin seeds
• Chia seeds
• Flax seeds
• Sesame seeds
• Sunflower seeds

Low-Carb Vegetables

• Celery
• Asparagus
• Cucumbers
• Broccoli
• Cauliflower
• Onions
• Okra
• Brussels sprouts
• Cabbage
• Tomatoes
• Peppers
• Lettuce
• Bok choy
• Carrots
• Mushrooms 
• Radishes
• Beets 
• Zucchini 
• Artichokes
• Summer squash
• Spaghetti squash 
• Kale 
• Mustard greens
• Seaweed 
• Swiss chard 

Fruit

• Avocados
• Blueberries
• Raspberries
• Strawberries
• Lemons
• Limes

Keto-Friendly Sweeteners

• Monk fruit
• Stevia
• Erythritol
• Swerve
• Xylitol

Snacks/Packaged Foods

• Beef jerky
• Pork rinds
• Olives

Foods To Avoid 

Grains (All)

• Wheat
• Rice
• Quinoa
• Corn
• Millet

Processed Grains (All)

• Chips
• Cereal
• Crackers
• Bread
• Pasta
• Traditional flour-based cake
• Traditional flour-based cookies

Beans 

• Chickpeas
• Hummus
• Black beans
• Butter (lima) beans
• Lentils

Vegetables (All Starchy Varieties)

• Potatoes
• Sweet potatoes
• Acorn squash 
• Butternut squash
• Cassava 
• Parsnips
• Turnips
• Pumpkin

Fruit (All High-Sugar Varieties)

• Apples
• Pears
• Mangoes
• Grapes
• Oranges 
• Apricots
• Pineapples
• Plums
• Figs
• Grapefruit
• Nectarines
• Peaches 

Sweeteners 

• Cane sugar (table sugar)
• Honey
• Molasses
• Agave
• Maple syrup 

Foods With Added Sugar

• Soft drinks
• Fruit juices
• Processed foods like brownies, donuts, granola bars, etc. 
• Gummy snacks
• Beef jerky made with added sugar

Sample 5-Day Keto Meal Plan

Day 1

Breakfast: Scrambled eggs with avocado and side of sliced tomatoes
Lunch: Romaine salad with blue cheese, bacon, and grilled chicken with olive oil and vinegar dressing
Snack: Beef jerky (sugar-free)
Dinner: Grilled salmon with side of roasted broccoli and cauliflower mash (with butter, salt, and pepper)

Day 2

Breakfast: Full-fat yogurt with crushed almonds, blueberries (small handful), and sunflower seeds
Lunch: Tuna salad wrapped in lettuce with mayo and tomatoes (one or two wraps depending on level of hunger)
Snack: Handful of almonds
Dinner: Grass-fed burger patty with cheese and mushrooms and side salad

Day 3

Breakfast: Omelet with cheddar cheese, ham, and tomato
Lunch: Keto charcuterie tray with olives, macadamias, cheese cubes, salami, and red peppers
Snack: Celery sticks with almond butter
Dinner: Spaghetti squash with meatballs

Day 4

Breakfast: Chia seed pudding with hemp seeds and blueberries (just a small handful)
Lunch: Greek salad with walnuts, avocado, and feta cheese
Snack: ⅓ cup macadamias
Dinner: Pork chops with cauliflower rice

Day 5

Breakfast: Keto pancakes made with almond flour
Lunch: Bacon, avocado, and tomato lettuce wrap
Snack: Smoked salmon pinwheels (salmon rolled up with cream cheese)
Dinner: Steak stir-fry with bok choy, broccoli, and cabbage over cauliflower rice

Prepare for the Keto Flu

When you decide to go keto, one potential downside is the short-lived “keto flu” that often precedes full-on ketosis. 

The keto flu consists of a group of flu-like symptoms that result due to the metabolic shifts that are happening inside your body. As your cells go through the process of learning how to use ketones as their primary fuel source, there’s a period of growing pains where normal-fuel metabolism may take a hit. 

During this time, your cells won’t have their regular supply of glucose, but they also won’t be fully adapted to using ketones. At the same time, your body will be losing a lot of water due to the depletion of your carbohydrate stores and the unused ketones that your body isn’t quite sure what to do with yet. 

This period can last anywhere from a few days to a few weeks, depending on the person. 

 Typical symptoms of keto flu include:

• Difficulty concentrating 
• Foggy-headedness 
• Fatigue
• Digestive issues (constipation, diarrhea)
• Nausea 
• Headache
• Irritability
• Dizziness
• Sugar cravings
• Difficulty sleeping
• Muscle cramps and soreness

To prepare for the keto flu, it can be very helpful to have a few supplements on hand:

Electrolytes

As your body excretes excess ketones during this beginning phase, it will also take electrolytes with it. This is one of the primary reasons that people feel a little off while going through keto flu. Luckily, there is an easy solution: Supplement with extra electrolytes. 

You can get electrolytes in a variety of forms: pills, liquid, or dissolvable tablets. Many people feel a lot better once they start getting electrolytes back into their bodies while transitioning into ketosis. 

It’s also helpful to add some sea salt to your water, as sea salt contains a variety of minerals that your body will soak up to replenish its stores. 

MCTs

During the transition into ketosis, your body may feel like it’s low on energy as your glucose stores deplete, so adding in some medium-chain triglycerides (MCTs) offers an excellent way to boost your fuel supply.

MCTs are a type of fatty acid that’s delivered directly to your liver to be used as energy. Typically, the fat you consume must first travel through your lymphatic system before your body can use it. MCTs, on the other hand, take an express trip, offering an immediate source of energy. 

Plan Food Ahead

Planning food ahead is always helpful when trying to eat healthy, and is twice as important when you’re going keto because most convenient foods aren’t keto-friendly. Therefore, if you want to set yourself up for success, having pre-prepared snacks and meals on hand is a hack you should take advantage of.

If possible, try to plan at least three or four meals for the week ahead. And to do so, try shopping on Sunday and commit an hour or two to food prep.

You’ll also want to have some snacks on hand that can help you curb your cravings—especially in the beginning. For that, many health food stores now carry keto-friendly crackers, ice creams, and desserts, and there are plenty of recipes online to choose from. 

Learn How To Eat At Restaurants 

Eating out at restaurants can be tricky on the keto diet, but there are a few tips that can make things a lot easier. This is, by no means, an exhaustive list:

• At burger joints, simply order your favorite burger with no bun. Many of the toppings like cheese and veggies are keto-friendly. 
• At Asian restaurants, a perfect keto go-to is always the stir-fry; just avoid the rice. You can ask for extra veggies or meat to make up for the lack of carbs.
• At Mexican restaurants, skip the tortillas, chips, and rice. Go for dishes like fajitas (no tortilla) or do a deconstructed burrito/burrito bowl with no rice or tortilla. 
• At sushi restaurants, go for the rice-free rolls or sashimi.
• At Indian restaurants, stick to kabobs and curries (but make sure the sauce isn’t made with sugar).

Check Your Ketones

If you’re serious about the keto diet, one of the best things you can do when beginning is to purchase some type of ketone monitor. Truly, the only way to know whether or not you’re in ketosis is to check your ketones. There are three options to choose from:

Breath Monitor

The breath monitor is the most expensive, least invasive, and provides moderate accuracy. Simply exhale into the device and it will measure the acetone level of your breath, instantly displaying your level of ketosis.

Urine Test Strips

Urine test strips are the cheapest option and can be helpful if you’re first experimenting with keto and not sure if this will be a long-term dietary change. They’re the least accurate, but they should give you a general idea of whether or not your body is producing significant amounts of ketones.

One caveat: As your body transitions into ketosis, you’ll lose a lot more ketones in your urine because your cells aren’t fully tuned up for using them yet. However, as your body becomes more keto-adapted, you will lose less ketones in your urine, which will make the test strips look like you’re not producing as many. For this reason, if keto is your long-term dietary goal, go for the other two tests. 

Blood Monitor 

The blood monitor is more expensive than the urine strips but not quite as expensive as the breath monitor. This is the most accurate test, as it directly measures what’s happening in your blood. However, it’s also the most invasive—you have to prick your finger each time you use it.

While there are many benefits associated with the keto diet, there are a handful of pitfalls to be aware of. 

You May Miss Your Favorite Foods

Mac and cheese, french fries, brownies, and ice cream are all off-limits on the keto diet. If you’re a comfort food-lover, this can be quite challenging at first. With that being said, there are plenty of recipes on the internet for keto-friendly alternatives to your favorite dishes, and you can even find some of them at your local grocery store. 

Keto Breath

A common side effect of keto is bad breath. This is due to the ketones that are excreted through your respiration that smell some say is sweet and fruity while others liken to nail polish remover. For many people, keto breath subsides after they become more fully keto-adapted. 

Constipation

Another common side effect of switching to a low-carb diet is constipation. If this is happening to you, it could be due to one of two reasons:

• You’re not eating enough fiber. 
  • Since fiber typically comes from foods that are higher in carbs, many people find that they aren’t getting as much fiber as they used to when they switch to a keto diet. A simple fix here is to just up your fiber intake by consuming more low-carb veggies and rich sources of fiber like flax seeds and chia seeds.

• You’re not drinking enough water. 
  • Hydration is crucial for proper bowel movements, and if you’re not staying hydrated, you’ll likely find that you end up with constipation. Since the keto diet will drastically reduce your appetite, you may find that your desire for water also diminishes. It’s essential that you keep drinking plenty of water on keto and make a habit of drinking liquids throughout the day to stay hydrated. 

Social Situations

Social situations like happy hours, potlucks, even group dinners can be tricky when you switch to a keto diet. Although it may be a transition at first, don’t let this hold you back. 

As more people are becoming aware of the diet, you’ll find that many are more curious than anything. Simply explaining why you’re choosing to forgo the carb-heavy dishes might be helpful.

It’s okay if other people don’t understand or agree with your new way of eating. Similarly, keto may be the right choice for you, but that doesn’t mean it’s the right choice for everyone. Diet is an individual choice based on individual needs and preferences.

The keto diet can yield some really impressive results, but it isn’t for everyone. Furthermore, you should always ask your doctor before beginning a new dietary protocol—especially if you’re currently taking any medications. 

Below is a list of people or situations in which the keto diet may not be a good fit:

• Anyone with an eating disorder history, as this diet may trigger prior ED behavior
• Type 1 diabetics
• People with kidney or liver disease
• People who are underweight, as you will likely lose more weight on the keto diet
• Children (unless otherwise recommended by their doctor)
• Pregnant women, as switching to a keto diet can mess with your hormones

The keto diet is an interesting take on low-carb eating, pushing your body to utilize an alternative fuel source when glucose is no longer readily available. As research on the keto diet continues to unfold, we’re getting insight into the many benefits that this way of eating may offer. 

With that being said, long-term nutritional ketosis is still a relatively new way of consumption, and it may not be for everyone. 

If you’re interested in trying the keto diet to see if it works for your body, be sure to check with your healthcare practitioner if you are taking any medications or if any of the above situations apply to you. 

Otherwise, start exploring. There are a lot of interesting ways to get high-quality foods into your diet, keto-style. Check out cookbooks, recipe websites, experiment on your own, or find some brands that make delicious keto-friendly products that you can rely on.

And if you need more support in starting a new nutritional program, take a look at our Intro to Nutrition guide.