The Keto Diet: Everything You Need to Know

The Keto Diet: Everything You Need to Know

September 25, 2018 19 min read

Raw steaks on the counter next to peppercorns and garlic

Looking for an eating plan that stands the test of time? Consider keto. The keto diet has been recommended by doctors since the 1920s as a treatment for conditions like diabetes and epilepsy, and since then, researchers have come up with even more uses for this way of eating. Here's what you need to know about what the keto diet does, how it works, and how it feels to live a keto-friendly lifestyle.

What is the Keto Diet and How Does it Work?

The ketogenic diet (often shortened to the keto diet) is a form of eating that emphasizes high-fat foods (such as butter and fatty cuts of meat) and de-emphasizes foods in the carb family (such as bread).

There are many high-fat, low-carb diets out there, including the paleo diet and the Atkins diet. But the keto diet is a little different.

The paleo diet, for example, is designed to help return you to a form of eating that might have been familiar to your caveman ancestors. Anything that an early person couldn't have found while hunting and foraging (such as corn or dairy products) is out. The keto diet has no such time restrictions.

The Atkins diet, on the other hand, is designed to work in phases. What you eat eat, and how much you can eat, is defined by what stage of the diet you're in. The keto diet has no such phases. You find a list of foods that you can eat, and you stick with it for good.

The keto diet can also be differentiated by an emphasis on fat. As the Harvard School of Public Health points out, other low-carb diets emphasize eating lean proteins. Keto, on the other hand, has a very high fat content (typically 70 percent to 80 percent, Harvard says), and protein intake is moderate.

As a result, the keto diet can be much easier to understand than other diets. Once you understand what you can and cannot eat, you simply retain that form of eating and watch the results come in.

Those results are based on the metabolic state the body moves into when carbs are no longer available.

Carbohydrates provide the energy the body needs to move through the day. When the body has no access to carbohydrates, it moves to processing fat stores for energy. A body burning fat stores is in a state of "ketosis," which is where this diet gets its name.

This process is effective, but it takes time to kick in. According to Harvard Medical School, it can take two to four days of eating less than 20 to 50 carbohydrates per day to enter ketosis. That's why it is so vital to stick closely to the diet. A slip could make you lose the progress you have made.

Scientific studies have proven that a body existing on this type of diet is radically different than a body consuming a different type of diet. For example, in a study in the journal Lipids, researchers found that a low-carb diet resulted in significant alterations in the fatty acids moving through the bloodstream, and the diet helped to reduce inflammation throughout the body.

These alterations, when combined with the other transformations a low-carb diet can bring about, can be helpful in the fight against both obesity and disease (more on that in a minute).

What Can You Eat on a Keto Diet?

Your keto diet is designed to eliminate quick sources of energy, so your body will burn fat in order to keep going. But your body can't survive on the fat it has stored for a rainy day. Your body will also need fuel from food.

Many of the calories you take in while following a keto diet come from fats. According to Medical News Today, keto-friendly fats come from coconut oil, butter, whole milk, almond oil, and other similar foods. You may also take in nuts, seeds, and avocadoes.

A bunch of almonds

You'll also eat protein while following a keto diet. Your meals might include:

  • Grass-fed beef
  • Eggs
  • Seafood
  • Fatty cuts of pork

Non-starch vegetables that grow above ground, such as broccoli, asparagus, mushrooms, and cauliflower can also be part of the diet. Other pro-keto vegetables are dark and leafy, such as spinach and kale. Adding these vegetables as salads, or drizzling them with oil and charring them over a grill, can make them tempting.

What Do You Avoid on a Keto Diet?

While you're following a keto diet, the goal is to significantly limit your intake of carbohydrates. That means traditional carb-friendly foods, such a bread and pasta, are strictly off limits. But there are other foods that you might eat often that could also be banned on a keto diet, and you might not even think of these foods as carbs.

For example, the Michigan State University Extension reports that fruit can have up to 15 grams of carbohydrate per serving. The extension provides suggestions of fruits that have a lower carb punch, but each item on that list has between 5.5 and 14.5 grams of carbs per serving. Eat more than one serving, and you could be over the limit. That's why most people who follow a keto diet omit fruits from their meals, if at all possible.

Milk can also be high in carbohydrate content. According to SF Gate, a standard cup of cow's milk can contain about 12 cups of carbohydrate, and that level can rise if the milk contains added sugar. Some dairy products, including cheese and cottage cheese, have lower carb levels, but for people following strict keto, drinking milk is out of the question.

Keto and Scientific Study

In general, nutrition experts chafe when presented with diets that label foods "good" and "bad." As an article in Today's Dietitian says, people should focus on their overall eating program, controlling portion sizes and getting adequate amounts of physical activity. People who follow a plan like this should be able to eat almost anything, the Academy says, without worrying about whether a food is accepted or banned.

Even so, nutrition experts have plenty of good things to say about low-carb diets like the keto diet. Multiple studies have been performed to uncover how the diet works, who it might help, and what it can do for people in need. These studies demonstrate quite clearly that limiting carbs could be helpful in addressing a wide variety of health issues.

One of the earliest studies performed on the keto diet was published in JAMAin 1925. Here, researchers found that a diet high in fat and low in carbs was helpful in treating young people with epilepsy. Study participants were placed on a form of the keto diet and followed for a period of 4 months to 2.5 years. Researchers found that a shift to this form of eating reduced the number of seizures the teens had, reduced seizure severity, or both.

Researchers have performed similar studies using animals, and here is where the story gets interesting. In a study in the journal Epilepsy and Behavior, researchers shifted dogs with epilepsy to a keto-like diet. They found that dogs moving to this diet were less excitable, chased objects with less intensity, and were easier to train. The researchers felt like the behaviors they shifted would be seen in dogs with attention-deficit hyperactivity disorder, so they felt confident that this diet could help people with ADHD.

Studies like this have exploded the market for research on the keto diet. Once officials understood that this type of eating could do more than help people to deal with seizures, they began to dig in and uncover other conditions that might benefit from a move away from carbs.

Can the Keto Diet Help You Lose Weight?

For anyone who has followed a conventional diet, reading through the list of preferred keto foods can be a little shocking. Listening to keto coaches telling their clients to eat full-fat servings of foods like cheese when there are low-fat versions available might seem even stranger. But there is some evidence that suggests that loading up on fatty foods really can help with weight loss.

In one study published in The Lancet, researchers reviewed published studies about low-carb diets, trying to understand if they really could help people to lose weight. The found that the diets were able to help people lose weight during the short term, and the researchers speculated that the diets were helpful because:

  • Reducing carb intake helped the body to expel retained water
  • Moving the body to ketosis (which happens when the body burns fat) can help to suppress the appetite
  • The foods available through the diet are filling and satisfying, so people eat less
  • The restricted nature of the diet can reduce the amount of calories people take in when they do sit down to a meal

This makes intuitive sense. If the meals you eat are filled with foods like meat and nuts that your body takes time to process, you are likely to feel full for a longer period of time. And if you avoid foods like rice and pasta, you are less likely to experience spikes and dips in blood sugar that can lead you to walk back into the kitchen in search of a snack.

But in order to scientifically prove that the keto diet has the power to help people both lose weight and keep it off, researchers would need to recruit many people to participate, and those people would need to be followed for months, if not years. Those studies are difficult to both design and execute.

For example, in a study in the journal Annals of Internal Medicine, researchers attempted a one-year study, to determine whether a low-carb diet or a conventional diet was best for weight loss. They wrote that people enrolled in the study weren't consistent about following the meal plans they were given, and a full 34 percent of people dropped out of the study altogether.

Studies like this highlight just how hard it is to stick with a diet like this. There are so many foods you simply can't eat, and cravings can get the best of anyone in a weak moment. But results like this also highlight how little we know about long-term weight loss and the keto diet. More research is required in order for researchers to make the benefits truly clear.

Infographic explaining how ketosis works

Can the Keto Diet Help with Polycystic Ovary Syndrome?

One woman in 10 of childbearing age has polycystic ovary syndrome (PCOS), according to the Mayo Clinic. The condition is caused, in part, by an imbalance of reproductive hormones. Women who have this condition may have irregular periods, unusual facial hair patterns, and ovarian cysts. They may also have acne and darkening of the skin. Women with PCOS may also be overweight, and for many of these women, that weight came on suddenly.

Researchers continue to study PCOS, and they've discovered something interesting about the way energy is metabolized in women with the condition. According to a researcher quoted in The Atlantic, women with PCOS tend to burn protein—not fat—while they're sleeping.

People who follow the keto diet know that it is possible to lose weight while asleep. When you aren't taking in any food at all, which happens often while you're asleep, your body is forced to burn off fuel stores. Typically, the body turns to fat for fuel while you're asleep. But if women with PCOS burn protein, they may retain the fat their bodies put on, even when they're not adding in more food. The keto diet may help, as it is low in protein. If these women have fewer protein stores available, their bodies may finally turn to burning fat.

Losing weight is a key part of the treatment plan for women with PCOS. As a study in the Journal of the Academy of Nutrition and Dieteticsdiscovered, women with PCOS who lose weight on any diet have fewer disease symptoms.

Weight loss helps because hormone levels are regulated by a body's size. The bigger the body, the more hormones the body puts out to keep the body healthy. Women with PCOS already have too many hormones circulating through their bodies. Carrying excess weight can make that issue worse. Losing weight could help the body to bring hormone levels down as well.

Researchers writing in the journal Nutrition and Metabolismexamined the benefits of the keto diet on women who had polycystic ovary syndrome. This study was small, as only 11 women were enrolled in the study, and only 5 completed the work. But the results are incredibly exciting. Researchers found that women who followed the keto plan had significant weight reductions, and they had lower body hormone levels. In addition, two of the women enrolled in the study became pregnant. Since PCOS is defined, in part, by infertility, this is an amazing result.

More research is required in order to fully understand how the keto diet truly helps women with PCOS, but these results demonstrate how much the diet might help women to improve.

Can the Keto Diet Help with Diabetes?

Diabetes can fundamentally change your relationship with food. A person with diabetes either cannot respond to or make enough insulin, which the body needs in order to process sugars in food. If left unaddressed, diabetes can lead to death.

According to the American Academy of Family Physicians, obesity is the top type 2 diabetes risk factor. With each added pound, the body struggles yet more to process insulin. Losing weight could keep early stages of diabetes from progressing, and continuing with weight loss could help to treat diabetes too.

Doctors can pair a weight loss recommendation with medications, but that wasn't always the case. According to an article in the journal Nutrition and Metabolism, doctors once had to lean on diet changes to treat their patients with diabetes. And the diet changes they recommended sound a lot like the keto diet. For example, researchers say, a 1923 textbook recommends that diabetic people follow a diet with foods in these ratios:

  • Fat: 75 percent
  • Protein: 17 percent
  • Alcohol: 6 percent
  • Carbohydrate: 2 percent

Keto followers might disagree with the alcohol recommendation, but they might appreciate the emphasis on fat and protein.

Banning carbohydrates makes sense, due to the blood sugar changes that take hold in the body when we eat these foods. According to the National Institutes of Health, each bite of carbohydrates is broken down into glucose, or sugar. Insulin enters the bloodstream to process that sugar so it can be used for energy.

Some types of carbohydrates are transformed into sugar very quickly, and they require huge amounts of insulin for processing. Eating those foods can be very difficult for people with diabetes, as they might be required to use massive doses of synthetic insulin to correct the imbalance that takes hold after every meal.

Banning carbohydrates can mean banning the highs and lows caused by carbohydrates, and that could lower the risk of diabetes complications.

Studies performed on people with diabetes suggest that the keto diet is truly helpful. In one such study, published in the journal Annals of Internal Medicine, researchers found that following a low-carb diet for two weeks helped obese people with diabetes to reduce the amount of calories they ate each day, and that helped them to lose weight. These people also had more control over blood glucose, and their bodies were better able to respond to insulin.

It is important to remember that the keto diet is a high-fat diet, and that can be a worry for people who have diabetes. Heart disease caused by cholesterol clogging arteries is a very real symptom of diabetes, and people with diabetes may have been coached for years to avoid all fats in order to keep cholesterol levels in check.

Even though the keto diet is high in fat, there is some evidence that the diet can help to reduce cholesterol levels. For example, in a study in the journal Experimental and Clinical Cardiology, researchers examined obese people following a ketogenic diet for 24 weeks. They found that the diet not only helped the people to lose weight, but the new eating plan also lowered LDL cholesterol (the artery-clogging type of cholesterol) while raising HDL cholesterol (the helpful form of cholesterol). Results like this suggest that following this meal plan won't make diabetes heart disease worse, and it could actually make things better.

Can the Keto Diet Help with Acne?

The little red dots that speckle our cheeks, backs, and chests arise due to a complex interplay between hormones, bacteria, and habit. When our hormone levels are out of balance, oil glands can move into overdrive and blanket the skin with a coating of oil that blocks pores. Those blocked pores, clogged with skin cells that cannot escape, can harbor cells of bacteria that can grow and proliferate. That can lead to a tiny abscess, commonly known as a pimple. Common treatments involve drying the skin, which pushes oil down lower and makes those abscesses harder to control.

The American Academy of Dermatology suggests that about half of women ages 20 to 29 have acne, as do about 25 percent of women ages 40 to 49. The Academy recommends a combination of medication and enhanced cleaning techniques in order to address ongoing acne issues.

Unfortunately, the medications people use to treat acne don't always work. In fact, an article in The Journal of Clinical and Aesthetic Dermatology suggests that 81 percent of women prescribed systemic antibiotics see no relief from the medication.

The keto diet may provide another answer. As researchers writing in the journal Molecular Nutrition and Food Researchpoint out, cutting carbs from the diet can help to modulate the number of hormones moving through the body. When there are fewer hormones available, the cycle of acne that begins with oil may finally be stopped.

In addition, excess weight can contribute to excess hormone levels in the body. Reducing weight through the keto diet could help the body to achieve greater hormone balance, and that could lead to lower acne levels.

Can the Keto Diet Help with Headaches?

Most of us experience headaches from time to time. But some among us experience headaches that are so severe that they impede the ability to work, communicate with family, or enjoy life. These are headaches that come on without warning and which can be remarkably difficult to get rid of.

Painkillers are a frontline treatment for headaches like this. In fact, in a study in the journal Headache, researchers found that opioids were given at 35 percent of emergency room visits for headaches. Painkillers like this can come with intense side effects, including addiction, so they are not solutions that are right for everyone. Diet changes might provide another option.

In a study in published in the journal Agri Pain, researchers asked people with migraine to follow a so-called "low glycemic" diet. Specifically, they were asked to avoid foods such as:

  • Bread, bagels, toast and pastries
  • Rice and pasta
  • Potatoes and corn
  • Sugar, chocolate, honey, molasses, and sweeteners
  • Watermelon and other melons

These are foods that might also be banned in a keto diet. Of those that followed this diet, the number of headaches they experienced dropped significantly.

Some types of headache, including migraines, are influenced by hormone levels. So the benefits headache sufferers experience are similar to those felt by people with acne and PCOS. If diet controls hormones, any disease with a hormone factor at play just might benefit from a diet change.

Can the Keto Diet Help with Cancer?

Just like healthy cells, cancer cells need fuel to survive. They use that fuel to help them to proliferate and grow, so they can spread throughout the body. Researchers are discovering that cancer cells function best with a specific type of fuel, and eliminating that source could mean reducing the effectiveness and the lifespan of a cancer cell.

Researchers writing in the British Journal of Cancer report that brain tumors rely on glucose for energy, while brain tissue can function on both glucose and ketones. We know that following the keto diet can mean reducing the amount of glucose that streams through the blood. When you eat fewer carbohydrates, there are fewer cells converted to glucose in the bloodstream. If brain tumors rely on that glucose to survive, cutting off the supply could be incredibly helpful. Brain tissue would have what it needs, while tumor tissue would starve.

Researchers writing in the journal Redox Biology take this idea one step further. They say that cancer cells starved of glucose and carbohydrates experience a form of oxidative stress. That metabolic stress, the researchers say, could make these cells sensitive to traditional cancer therapies, including chemotherapy and radiation.

Put these two studies together, and they seem to suggest that moving to a keto diet could starve out some types of cancer cells, while making others more treatable.

Obviously, cancer is an incredibly complex disease that can be influenced by a variety of factors that have nothing to do with diet. Smoking levels, pollution, genetics, and more all play a role in the development of cancer. But for people with cancer, these studies seem to suggest that it's worthwhile to consider a keto diet, with the help and supervision of their doctors.

What's It Like to Go on the Keto Diet?

Now that you understand what the keto diet is and how it might help you, the temptation to give the diet a try might be rising.

Finding a meal plan you like and can follow is a top challenge cited by people who follow this diet. There are plenty of articles out there that can tell you what you should eat and what to avoid, but the advice you read can be conflicting or even downright contradictory. Can you eat squash? Should you eat coconut oil or flakes? For some people, reading all of the conflicting lists of foods can be discouraging (and even a little frustrating). Before you sign on, choose one app or website as your go-to keto source, and rely on that one source for all your questions.

The very restricted diet can also be a little hard to stick to. You may find that you have deep-set cravings for things you once ate with abandon (like toast with sugary jam). You may also grow bored with the foods you are allowed to eat. Make sure your go-to source is filled with recipes and variety, so you can mix things up when you need to.

When you are new to the diet, you may experience what experts call the "keto flu." As an author writing for the Cleveland Clinic reports, the flu can leave you feeling exhausted and irritable. You may struggle to think clearly, and you may not feel as though you have the energy to get through the day. This phase will pass if you stick with the diet, but it can be hard to move through.

As you cut fruits and many vegetables from your meal plans, you may also deal with constipation. You may find that you just don't feel the urge to go, or you may feel as though you need to go and simply can't. If this happens, adding more vegetables to your everyday meals may help.

Keto Diet Products You Need

As we mentioned, following the keto diet isn't always easy. You may find that you grow bored with the "approved" foods you can eat, and you may always be on the lookout for additional fats that can help you get through an episode of the hangries.

Enter keto supplements. Keto supplements contain a mix of healthy fats and collagen, and they're optimized to provide you just what you need to deal with keto challenges.

The fats included in the supplements help you to feel full and satisfied, so you will resist the urge to open up a bag of chips or cookies and blow your diet altogether. In addition to using a supplement as a snack, you can also add a dash of supplements to your planned meals, to ensure that you are getting the fats you need to stay in ketosis, so you won't have to start the diet all over again.

The collagen helps to ensure that your body has all of the building blocks required to maintain healthy tissues. Since the keto diet is so restrictive, you may be missing out on the collagen your body needs for soft-tissue repair. With a supplement, you can get what you need.

Keto supplements are made to swirl in water, tea, or coffee. Choose your keto-friendly drink and add your supplement to it. Collagen-based products can move through fluids that are either hot or cold, so you have plenty of options.

Keto Diet Q&A

What can I eat for breakfast on keto?

Typical bread products that might fill up your breakfast plate, such as toast or waffles, are not compatible with keto. Instead, your breakfast will be made up of:

  • Eggs
  • Sausage
  • Vegetables
  • Fats

Consider this: Fry up two sausage patties, and add in an egg fried up in olive oil. Pop a few peppers and an avocado in for spice, and you have a quick breakfast sandwich that will keep you full all morning.

The web is full of recipes just like this, including recipes for smoothies, if cooking in the morning isn't quite right for you.

How do I start a keto diet?

There are all sorts of variations on the keto diet, and people new to this type of eating can find the rules confusing. Most sites have long lists of foods that are "approved" and those that are not. Those lists can shift from site to site, and you might spot contradictions between sites.

Before you start your diet, choose a website or download a keto app. Stick to that sole source of information to make meal planning less confusing.

In addition, you will need to stock up on keto supplements, to help you kick off your diet on the right foot. Order them now, so they will be in your possession on the first day of the diet.

With a source of information and supplements in hand, you'll need to head to the store to stock up on the food you'll need. It might also be wise to toss out or donate the food you have in your pantry that you will no longer eat.

What fruits can I eat on keto?

Most fruit is banned from the keto diet, as fruit tends to be high in carbohydrates. A juicy peach eaten as a snack has the potential to derail your entire diet plan for the day, so in general, it is best to avoid fruit when you can. Tiny amounts of berries, such as raspberries and blackberries, might be acceptable.

What vegetables can I eat on keto?

Your body needs plant material to function at an optimal level. All of the micronutrients and minerals that keep you feeling sharp and strong are packed inside fruits and vegetables. Since you cannot eat fruits on the keto diet, you will need to get your nutrients from vegetables.

Keto experts choose vegetables that grow above the ground. Top keto veggies include:

  • Avocado
  • Spinach
  • Asparagus
  • Olives
  • Eggplant

Is the ketogenic diet dangerous?

In order to determine if a diet is truly dangerous, researchers would need to entice people to follow that diet for months or even years, and compare how well they do on standard health measures when compared to people who don't follow the diet.

Studies like this haven't been performed yet. One study on the long-term side effects of keto, published in the journal Experimental and Clinical Cardiology, lasted for only 24 weeks. That just isn't long enough to give us the data we need to determine whether this diet is truly free of dangerous side effects for those who follow it for long periods of time.

What are the side effects of the keto diet?

The goal of the keto diet is to push the body into ketosis: A state at which stored fat within the body becomes fuel. People who are in a state of ketosis report feeling clear, full, and calm. People on the cusp of ketosis report feeling emotional, upset, confused, and incredibly hungry. Moving out of ketosis can mean dealing with this "keto flu" again.

As you adjust to the diet, you may also feel fatigued. Your body has not yet grown accustomed to the new source of fuel, and that means you can feel as though you simply don't have the energy to get through the day.

Cutting back on fruits, beans, and starches can also mean dealing with ongoing constipation. This is especially common in people who eliminate vegetables from their diets, in addition to cutting back on fruits.

How do I know when I am in ketosis?

The only real way to spot ketosis is through a blood or urine test. But there are a few other side effects that tend to take hold when you've hit the blood sweet spot. The biggest side effect you may notice involves your breath. You may get a whiff of acetone on your breath, or it may smell somewhat fruity to you or the people around you.

Can I lose weight fast on a keto diet?

You can lose weight on the keto diet, but the pounds you lose quickly may be due to water loss. It can take several weeks for you to see lasting results with this diet plan.


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