Many of us know at least one person—if not several—who swear by keto.
We also know plenty who’ve said “it was awful.”
Which makes it sound a lot like… ALL DIETS.
So here’s the only question that matters:
Is the keto diet right for you?
And if you’re a coach, should you recommend it to your clients?
In this article, we’ll help you figure it out.
How? By helping you understand what the keto diet is, where it came from, and what all the hype is about. You’ll learn the pros and cons so you can weigh whether it makes sense for you (or your clients).
Plus, we’ll connect you to a food list that shows you what and how much to eat.
And then we’ll take you out to dinner… okay, that’s obviously going too far. (We don’t even know each other yet!)
But the rest of it? We’ve got you covered.
Keto diet basics
By keeping carbohydrates very low, ketogenic diets (or keto for short) trigger your body to use ketones—instead of glucose—as its primary fuel source.
To better understand what that means, we need to go into a little biology.
Human bodies require a constant supply of energy, primarily in the form of glucose. You get that glucose, mostly, from eating carbohydrates.
So what happens if you don’t eat carbohydrates?
Ketosis and gluconeogenesis, to the rescue.
Our bodies house an elegant system of safety nets that have gotten us through the hard times of human history. (Think: famines, hunting things that sometimes got away, no vending machines…)
If food isn’t immediately available, our bodies turn to stored glucose—called glycogen—mostly found in liver and muscle cells.
We have enough glycogen to provide a couple of days worth of glucose. But once glycogen is depleted, and food is still scarce, our nerve, brain, and blood cells start to get, well, hangry.
Cue the back-up systems:
▶ Ketosis turns on when overall calories or carbohydrates are very low. This might happen when fasting, exercising intensely for a long duration, sleeping, and (you guessed it) following the keto diet. Our liver breaks down fat to create ketones, which can feed cells in lieu of glucose. (Although most cells prefer glucose over ketones any day, brain, nerve, and blood cells are particularly picky about getting energy from glucose.)
▶ Gluconeogenesis is your body’s way of making glucose from non-carbohydrate sources, like fats and proteins. These fats and proteins can come from the diet, or they can come from stored fat, muscle tissue, or organ tissue.
Ketosis and gluconeogenesis are normal responses to glucose depletion.
But how did ketosis become a central feature of a trendy diet?
The keto diet wasn’t developed for weight loss.
It was developed to treat epilepsy.
Physicians understood that fasting helped to reduce seizures. But they obviously couldn’t tell patients to fast indefinitely.
The keto diet, however, mimics fasting by triggering ketosis.
It’s not clear why ketosis reduces seizure frequency. It may be that manipulating macronutrients has an effect on neurotransmitters and brain metabolism.1 There are many theories, but the truth is, no one knows for sure.
Eventually, the fitness industry discovered the keto diet. And naturally they thought, “If the keto diet mimics fasting, this must be the key to getting totally cut, while still eating cheese!”
(As with most magic bullets, the reality is more complicated, and not particularly magical. But more on that later.)
Carbs: How low are we talking, exactly?
Generally: The ketogenic diet consists of about 70-90% calories from fat. As a result, the remaining 10-30% of calories will come from a mix of carbohydrates and protein combined.
Why the ranges? Because there are several keto and low-carb diet variants.
|Diet||Protein %||Carb %||Fat %||Description|
|Original keto||6%||4%||90%||Designed to induce and maintain ketosis, as a dietary intervention for epilepsy.|
|Popular keto||20%||5-10%||70-75%||A more balanced and sustainable version of the original keto diet, as modified by popular diet culture. (Usually intended for weight loss.)|
|Performance keto||30%||5-10%||60-65%||Used to support athletic performance and muscle development.|
|Low carb||~30%||20%||50%||Carbs are lower than a typical balanced macronutrient diet, but the exact ranges can vary. All keto diets are low carb, but low carb doesn’t necessarily mean keto.|
Most Americans consume a moderate- to high-carb diet, getting just under half of all their calories from carbs.2
(Oh, the joy of bottomless noodle bowls.)
Despite this, some people love the keto diet. They say they’re not as hungry, and that their energy feels stable.
Meanwhile, others feel miserable. Their energy or athletic performance suffers. They develop digestive problems. And heck, they just miss pizza and fresh, in-season peaches.
In fact, the keto diet can be so tough to follow that even people with epilepsy often prefer medication to the diet.
Ketogenic diet benefits
People who have success with the ketogenic diet (understandably) want to toot the keto horn of glory extra loud.
“On what other diet can you eat butter?! And cream??!”
And they’re not wrong. A strict ketogenic diet offers several benefits.3
Benefit #1: The keto diet may help you lose weight faster (initially).
It’s true: People who do keto seem to lose slightly more weight more quickly than people who do other diets.4 5 6 7
This relatively quick drop on the scale can be super motivating.
“Yay! It’s working!”
Unfortunately, that initial drop in body weight has more to do with water loss than fat loss.
Here’s how that works:
When you stop eating carbs, your body’s carbohydrate stores—a.k.a. glycogen—quickly get used up. Glycogen holds a lot of water, so when glycogen drops, water weight does too.
Your liver and the muscles are the main storehouses of glycogen. The bigger your liver and/or muscles are, the more glycogen they can hold.
That’s why those huge, brawny MMA fighters can drop 15-20 pounds before a weigh-in, just by manipulating carbs (and usually salt).
But if you analyze the body composition of those water-manipulated athletes—or an early keto dieter—you’ll see that their body fat percentage probably hasn’t changed much.
In other words:
Manipulating body water will change weight mass, but not fat mass. You’re not actually leaner, you’ve just lost water.
For better or worse, that early scale drop can make people feel like they’re moving in the right direction, which can inspire them to more positive actions.
Benefit #2: The keto diet may help suppress your appetite.
When someone restricts calories, they often experience rebound hunger that makes that lower-calorie diet hard to follow consistently.
But one study showed that when people go on a calorie-restricted, keto-style diet, they experience less of this compensatory hunger.3 They may even spontaneously consume fewer calories, other research has found.8
Why might this happen?
Reduced food options can lead to something called “sensory-specific satiety.” Meaning, when people eat the same foods all the time, those foods become less appealing.9
Also, liquid calories—soda, juice, even milk—are generally off-limits on the keto diet, so people usually consume a greater proportion of calories from solid foods, which are more filling.10 11 12
Lastly, higher blood levels of ketones—which rise when carbs are restricted—may help to suppress appetite.13 14 15
Benefit #3: The keto diet might feel psychologically freeing (for some).
With keto, there’s not a lot of negotiation. The rules are pretty strict: You can eat this, but not that.
While many people find keto too constraining, others actually like the rules and clarity.
It means less options, and therefore less decision-making. This can free up a lot of mental space, which makes a diet (at least psychologically) easier to follow.
Benefit #4: The keto diet may help improve blood sugar and insulin sensitivity.
The keto diet may improve hemoglobin A1c (a marker of average blood sugar levels) in people with type 2 diabetes16 17 and/or metabolic disease.18
But the benefits of keto on cholesterol and triglycerides—two other markers related to metabolic disease—aren’t as clear.
Some research shows the diet supports normal blood lipid levels—raising HDL (“good”) cholesterol and lowering LDL (“bad”) cholesterol.19 20 21 However, other research shows it can raise LDL cholesterol22, which is typically a risk factor for chronic disease.
So, while keto may help correct metabolic disease for some—including better cholesterol profiles and blood sugar regulation—it can worsen cholesterol and other markers for chronic disease for others.
Unfortunately, that’s where nutrition research is limited, and individual variability makes things, well, kind of unpredictable.
We do know, however, that fat loss can help normalize cholesterol levels and improve blood sugar regulation.23
In other words, if the keto diet is helping you lose weight, and you’re maintaining a regular movement routine and eating as many colorful veggies as possible, you’re probably on the right track. If you’re worried about cholesterol, you can work with your doctor to check your levels.
Ketogenic diet cons
Just as some people feel super on the keto diet, others feel like… crap.
They’re draggy and bloated, and are tormented by dreams of sprinting baguettes that remain just out of reach. From a nutritional standpoint, a long-term, strict keto diet also has some drawbacks.
Con #1: It’s lonely being the person who can never eat bread, pasta, or heck, even an apple.
It seems like so many of life’s celebratory moments revolve around carbs.
Cake for birthdays. Beer on Fridays after work. Sharing a cookie with your niece. Your aunt’s famous dumpling soup.
All of that can make the ketogenic diet feel a little… isolating.
And if there’s anything we know about diets, it’s that they only work so long as you can stick to them.
Which brings us to our next point.
Con #2: The keto diet is really hard to stick to long term.
Many keto dieters start adding more carbs over time—and this includes people who are trying to follow keto strictly, long-term research (trials lasting over six months) shows.
By a year’s mark, most keto dieters have gone from less than 50 grams to over 100 grams of carbs per day.24 25
That’s roughly the combined amount of carbohydrate in a bowl of cereal, a banana, a bagel, and a serving of rice. This means about 16 to 22 percent of their daily calories are coming from carbohydrates (assuming a 1800- to 2400- Calorie diet). By any measure, these intakes aren’t keto.
Luckily many people can experience the benefits of keto (especially improved blood sugar) without strictly following keto or staying in ketosis.26
Con #3: The keto diet might back-up your bowel movements.
The keto diet—which reduces or eliminates fruits, starchy vegetables, whole grains, and legumes—tends to be extremely low in soluble and insoluble fiber. (This is especially true in the original version of the keto diet.)
Poop frequency is correlated with eating fiber-rich plants, as well as drinking fluids (alcohol excluded).27
So, as you might imagine, people on the keto diet may find they’re hitting the loo for a number two a little less frequently.
It also means that the healthy bacteria in your gut—whose primary food source is soluble fiber—isn’t getting fed. Indeed, adherents of the ketogenic diet show a decreased amount and diversity of beneficial intestinal bacteria.28 29
Two possible workarounds to this issue: a fiber supplement and possibly a probiotic supplement. (To learn more about the pros and cons of probiotics, check out: Probiotics: Do they really work?)
Con #4: A keto dietary pattern might increase your risk for a variety of diseases.
In addition to being low in fiber, a strict keto diet backs colorful fruits and vegetables, and is high in fat, including saturated fat.
Here’s why that kind of dietary pattern can lead to problems:
▶ Fruit, vegetable, and fiber intake is protective against a range of diseases like cancer, cardiovascular disease, type 2 diabetes, and overall mortality.30 31 32
▶ Meanwhile, excess saturated fat consumption is associated with an increase in cardiovascular disease33 and may promote fatty liver disease.34 (To find out how much saturated fat is safe to eat, check out: Saturated fat: Is it good or bad for you?)
But you don’t have to do keto to follow this kind of dietary pattern.
The Standard American Diet—often called the SAD diet—is similarly low in fiber, fruits, and vegetables, and high in saturated fats. Unlike keto, it’s also high in refined carbohydrates.
And, as you may have guessed, the SAD diet is also linked to a range of chronic diseases.35
These dietary patterns—whether via keto diet or SAD—aren’t likely to serve our long-term health.
The keto flu: Yucky, but not contagious
As your body switches from burning glucose to burning ketone bodies for energy, flu-like symptoms—like drowsiness, fatigue, nausea, low appetite, and abdominal pain—can pop up.
Some people also experience concentration issues, trouble sleeping, and irritability or low mood.
This doesn’t happen to everyone, and it’s usually over in a week.
To ease the symptoms, stay hydrated, rest when you can, and make sure you’re getting enough calories to meet your energy needs (even if most of those calories won’t come from carbs).
If symptoms of fatigue, low appetite, or dizziness become severe or persist for more than a week, discontinue the diet and consult your medical doctor.
Con #5: The keto diet is missing some key nutrients.
In order to reduce carbs, the keto diet restricts or eliminates grains, legumes, and many vegetables. People can eat some non-starchy vegetables (like leafy greens, cucumber, and celery), but in limited amounts. For fruit you’re looking at a small apple or one handful of berries.
If you’re doing a strict version of the diet—like the original keto diet—protein foods are also relatively sparse. (Popular and performance keto diets allow more protein, so this isn’t a problem in these versions.)
Along with fiber and (potentially) protein, the keto diet tends to be deficient in these vitamins and minerals:
- Vitamin B1
- Vitamin B2
- Vitamin B3
- Vitamin C
- Vitamin D
If you’re doing keto long term, consider supplementing with a daily multivitamin and mineral supplement.
Can you use the keto diet to manage medical conditions?
As mentioned, there’s evidence that the keto diet (or actually most low-carb diets) can improve the health status of those with type 2 diabetes and/or metabolic disease.17 18 19
However, if you’re a coach, remember that unless you’re specifically qualified to do so, you can’t directly treat a medical condition like diabetes or high cholesterol.
If your client is diagnosed with one of these conditions and you think a low-carb or ketogenic diet might help, work with your client’s doctor.
Alternatively, you can also encourage your client to seek out a professional specifically dedicated to this area. In Canada, look for a Certified Diabetes Educator (CDE). In the US, look for a Certified Diabetes Care and Education Specialist (CDCES). These professionals are qualified to treat and manage diabetes through a combination of diet, lifestyle modifications, and if needed, medications prescribed by the individual’s doctor.
Who shouldn’t do keto
While many healthy adults can try a ketogenic diet without issues, the diet’s a hard “no” for some.
Here are a few of those cautionary groups:
Putting pregnant humans on a restricted diet doesn’t tend to get a pass from the ethics board, so most of the research we have on keto during pregnancy is on rats or mice.
And the rodent data is pretty grim: Ketogenic-style diets fed to pregnant rats altered organ growth in embryos,36 or dramatically increased the chances of pups dying within a week of birth.37
Getting the edge over an opponent may mean racing fractions of a second faster or lifting fractions of a pound more. Athletes and coaches know: Every advantage (however slight) counts.
And based on the most compelling research, a severely low carb diet can impair performance as much as eight percent.38 39
People with type 1 diabetes
Although the keto diet (and low carb diets in general) can be helpful for managing type 2 diabetes, type 1 diabetes is a whole different ball game.
People with type 1 diabetes can’t make insulin. You can think of insulin as a key that lets sugar from the blood into the cell, where it can be used for energy.
Without insulin, sugar can’t enter the cell. It hangs out in the blood, causing damage to tissues and organs. If blood sugar builds up enough, it creates a life-threatening state called ketoacidosis.
Although the keto diet can lower blood sugar coming from dietary sources, potentially reducing the amount of insulin someone needs to take, people with type 1 diabetes will always need medication.
That’s because blood sugar can rise due to reasons other than carbohydrate consumption. (For example, stress can raise blood sugar.)
And, although diet and exercise can be excellent complementary therapies for type 1 diabetes, they too must be tightly controlled and monitored. Manipulating carbohydrate intake (or even engaging in extreme exercise) can be risky, and definitely requires medical supervision.
Ketosis and ketoacidosis: Not the same thing
They sound similar: They share the prefix keto-, because they both involve ketone production.
But ketosis and ketoacidosis are very different things.
Ketoacidosis—often called diabetic ketoacidosis (DKA)—is a life-threatening occurrence that happens when both ketones and blood sugar get dangerously high, causing the blood to become very acidic.
Ketoacidosis can occur in people with type 1 diabetes if they don’t get enough insulin, or if insulin isn’t working well due to illness, infection, pregnancy, stress, or too much dietary sugar.
Ketosis is a normal response to low blood sugar. When glucose is depleted, the body turns to fat for energy, which releases ketones. Ketosis is not an emergency, nor is it harmful.
Ketoacidosis (high blood sugar and high ketones) = Medical emergency
Ketosis (low blood sugar and ketone production) = Normal response to low blood sugar
People with a history of disordered eating
It can be risky to play with restrictive diets if you—or your client—has dealt (or deals) with disordered eating, even if the interest in the diet isn’t directly related to weight control.
Instead, people struggling with disordered thoughts, feelings, and behaviors around food can work on developing appetite awareness and mindful eating, as well as learn to detach food choices from self-worth, success, or failure.
How to coach clients
To do a ketogenic diet well, it takes strategy and planning.
That’s where coaches come in.
Here are a few big-picture tips to help your clients do a keto diet in the healthiest way possible.
1. Explore and experiment.
If your client is determined to try keto, don’t give them a lecture about potential nutrient deficiencies and the perils of bacon.
That’ll just alienate them—and likely prompt them to find another coach who will coach them through a keto diet.
Respect your client’s desires and perspectives, even if you disagree with them.
If a client comes to you pumped to keto their butt off (and doesn’t fall into one of the aforementioned no-no groups), here’s a great line to use:
“Let’s try it!”
Get curious about their attraction to the diet, and their ability to execute it.
Do they have the time (and interest) to prepare special meals, negotiate social eating, and tally grams of carbs? Can they afford almond flour-everything?
Help them know what to expect, but cultivate a sense of discovery, too.
2. Evaluate how things are going.
As your client progresses, continually check in with one of our favorite coaching questions: “How’s that working for you?”
(We actually created a quiz to help you—or clients—figure this out: Best diet quiz: How’s that diet REALLY working for you?)
Be honest about the feedback: What’s worked well? What hasn’t?
Maybe the diet is making them feel lethargic and moody, or they miss eating what their family is having. Or maybe it’s going great, and they can’t wait until their next filet of macadamia nut-crusted salmon with a side of cloud bread.
Capitalize on what’s going well, and help your client do more of that. For the stuff that’s not working so well, troubleshoot with your client on how to make it easier, or drop it and move on.
The keto diet works best in very specific populations, and if your client doesn’t fall into one of them, let them know it’s not a personal failure.
3. Help clients navigate social eating.
For clients, sometimes getting healthier does mean making different choices from their loved ones, and having awkward (but important) discussions about health priorities.
However, when their diet is markedly and consistently different from the people around them, it can be a little isolating.
So encourage clients to participate in communal eating, because the alternative means missing out on a rich part of life—connection to others.
To make that happen, help clients brainstorm ways to be social while remaining on keto. You might suggest that clients:
- Make keto-friendly dishes to bring to parties.
- Eat keto-friendly foods that overlap with their family’s nutritional needs.
- Decide if and when they want to make exceptions to their diet (Christmas dinner, their daughter’s birthday, a foodie weekend trip with friends).
4. Supplement strategically.
People following a strict keto diet long term should work with a qualified nutritional or medical consultant to help prevent and manage any deficiencies.
Focusing on specific nutrient-dense foods (e.g. colorful, non-starchy vegetables, Brazil nuts, omega 3-rich fatty fish, and small portions of berries) can help fill nutritional gaps.
But often, supplements—like fiber or specific vitamins or minerals—will be part of a keto dieter’s long-term health protocol.
5. Stay within your scope of practice, and refer out as needed.
Unless you’re licensed for medical nutrition therapy, you’re not authorized to prescribe any type of diet for medical conditions.
Don’t tell your client that they should go on a keto diet to cure their diabetes or their epilepsy.
Also, the keto diet can alter certain cardiovascular markers—LDL and HDL cholesterol, triglycerides—which only a doctor can interpret and monitor.
A nutrition coach can help with meal planning, keeping a food journal that tracks the correlation between diet and symptoms, as well as overall support and accountability.
The point is: You can play a tremendously important role in helping clients stick to a diet, just do it within your scope of practice.
The keto diet plan: What to eat
The keto diet is largely composed of fat—but that doesn’t mean eating bacon and dark chocolate indiscriminately.
Food quality and nutrient density still matter.
While many people following a strict ketogenic diet will still need to supplement, they can still get a good range of nutrients from:
- Non-starchy vegetables
- Occasional other fruits and starchy vegetables in small portions
- Omega 3-rich seafood
- Poultry and eggs
- Pastured meats
- Quality whole food fat sources like avocado, nuts, seeds, egg yolks, coconut, and olives
For a complete visual guide, use our keto diet food list infographic.
And to find out just how much protein, carbs, fat you should eat on the keto diet, plug your info into our macros calculator. (It’s FREE and gives you a customized plan based on your diet preferences and goals.)
As you use these resources, please keep in mind: There is no one-size-fits-all keto diet.
Our list will help you focus on minimally-processed whole foods while also prioritizing overall nutrient intake balance as much as possible.
If you’re a coach, you may have clients who follow different keto diets—and that’s okay. The important part: helping them stay successful and healthy on whatever diet (or no-diet) they choose.
The truth is, some people do feel and do better on a ketogenic diet.
Meanwhile, others thrive on a higher carb diet.
For better or worse: There’s no one diet that’s a magic bullet for everyone.
As a human species, we’re diverse. And that’s actually worth celebrating.
If you’re a coach, or you want to be…
You can help people build nutrition and lifestyle habits that improve their physical and mental health, bolster their immunity, help them better manage stress, and get sustainable results. We'll show you how.
If you’d like to learn more, consider the PN Level 1 Nutrition Coaching Certification.