Everything You Need to Know About the Keto Diet for Beginners
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For a beat there, the ketogenic diet was everywhere.
Lebron, Tebow, Kardashian—you name the headline-maker and they were likely
working their way to or living in ketosis. It was all Joe Rogan ever talked about.
Nutrition > Keto Central
Eating all the fat you want sounds like a delicious way to lose weight—but
is it worth sacri몭icing carbs?
BY MELISSA MATTHEWS, CHRISTINE BYRNE AND CHRIS MOHR, PH.D., R.D. PUBLISHED: APR 25, 2022
HEALTH ENTERTAINMENT FITNESS STYLE GROOMING
2. Chipotle popped in to oﬀer something called a keto "Lifestyle Bowl" on their menu.
Keto even supported the continuance of at least one member of the original Jersey
And for a diet that came from bizarre and mysterious origins, you can't help but be
in awe of its staying power. Is keto as trendy as it once was? Probably not. But you
likely still have friends who swear by the bread-free, butter-heavy diet.
The foundations of the ketogenic diet haven't changed: eat a fat-and-protein-rich
diet that's ultra-low in carbs and you'll enter into "ketosis," a state where your
body burns fat as its primary fuel source.
But what has changed is that we now have perspective on the diet. And, with that
perspective, nutrition experts everywhere are breathing a sigh of relief.
Sure, the keto diet is known to deliver quick weight loss results at the beginning.
But those who love eating nothing but bacon, cheese, and avocado all day might
be disappointed to learn that researchers have yet to prove that keto has any
lasting health beneﬁts for the average person, and some worry about the potential
health risks of consuming so much fat and so little carbohydrate. What’s more, the
research is pretty clear that keto isn’t any more eﬀective for long-term weight loss
than other diets out there.
So, in short, keto faced a reality check. If you're thinking about trying keto and
want to determine if it's worth sacriﬁcing carbs, here's a healthy dose of that
What is ketosis?
Ketogenesis has existed as long as humans have.
If you eat a very low amount of carbohydrates, you starve your brain of glucose,
the organ's main fuel source. Your body still needs fuel to function, so your brain
ﬂips the switch to tap into your reserve of ketones, which are compounds the liver
creates from fat when blood insulin is low. This process is known as ketosis: It’s
like when a hybrid car runs out of gas and reverts to pure electricity.
3. There's nothing inherently magical about ketones. In fact, you already have them
in your body. “Your liver produces ketones all the time, but the rate depends on
carbohydrate and protein intake,” says Jeﬀ Volek, Ph.D., R.D., a professor of
human sciences at Ohio State University.
When the majority of your diet is made up of carbs and protein—as the average
American diet is—ketogenesis (the process of producing ketones) slows. Replacing
carbs and protein with fat will put your body into ketosis, thus ramping up ketone
production. Essentially, you'll burn fat instead of carbs for energy. Ketosis is not
instantaneous, and the process takes about three days to induce—often with some
side eﬀects during the transitioning stages. (More on those later!)
What can you eat on the keto diet?
To understand which foods you should and which you should avoid on the keto
diet, you have to ﬁrst consider three key nutrients: fat, protein, and carbohydrates.
A ketogenic diet generally requires that fat comprise 60 to 80 percent of your total
calories. Protein take up about 20 percent, while the remaining 10 percent comes
from carbs. Proponents of a ketogenic diet often recommend limiting your carb
intake between 20 to 30 grams per day in order to maintain ketosis. For
perspective, that’s the equivalent of about half a medium bagel.
Yes, that all. Half a medium bagel.
And remember, carbs aren’t just
present in processed foods; a cup of
chopped broccoli has 6 grams of carbs,
a cup of chopped carrots has 12 grams,
and a cup of Brussels sprouts has 8
grams. In other words, eating the
recommended ﬁve servings of
vegetables per day (because fruits,
which are higher in carbs, are pretty
much oﬀ the table) will probably put
you at your max carb allowance.
4. PRECISION NUTRITION
If this sounds like the Atkins Diet from
the 1990s, it’s close, but “ketogenic diets tend to be more severe in carb restriction
and have a more moderate protein restriction,” says Spencer Nadolsky, D.O.,
author of The Fat Loss Prescription.
Though you can eat bacon on a ketogenic diet, the rest of the spectrum is limited.
Starchy vegetables like potatoes, corn, and squash are too high in carbs. Same
with most fruits. Milk, beans, rice, pasta, bread: nope.
To stay as healthy as possible, keto dieters should eat plenty of low-carb vegetables
like red bell pepper, kale and cauliﬂower. These vegetables contain important
micronutrients (AKA vitamins and minerals), as well as ﬁber, which is linked to a
lower risk of heart disease, diabetes, and cancer.
The rules of keto impact more than just mealtime, too, since juices, sodas, and
alcohol will knock you out of ketosis.
So what does a typical day of eating look on the ketogenic diet?
Breakfast: 4 eggs, 1/2 avocado, 1 to 2 Tbsp olive oil
Lunch: 4 oz baked salmon with 1 Tbsp olive oil, 1/2 bunch asparagus with 1
to 2 Tbsp butter
Dinner: Rib-eye steak, 2 cups spinach with coconut oil, 2 oz macadamia nuts
Most men consume nearly half of their calories from carbs, according to the
Centers for Disease Control and Prevention. And that’s not a bad thing; it’s actually
within the range of what the Dietary Guidelines for Americans recommend for
optimal health. So, it goes without saying that cutting your intake to less than 10
percent will be a challenge, and may pose some risks.
We'll get into those a little later, but, ﬁrst, the ketogenic does have some beneﬁts
that are worth highlighting.
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5. How do you know if you're in ketosis?
Sure, eating bacon and cheese may sound like a dream but achieving ketosis isn't
easy, says Melanie Boehmer, a registered dietitian at Lenox Hill Hospital.
"Sometimes people try and teeter into it and they won’t lower their carbohydrates
enough," Boehmer says. She recommends eating no more than 20 to 30 grams of
carbohydrates per day to maintain the ketogenic state.
Often people think they can eat unlimited amounts of meat on the diet, but that
isn't true. Consuming too much protein will also decrease ketone levels.
Cheat days, even if they are rare, and drinking alcohol can take you out of ketosis,
You can determine whether you're actually in ketosis by purchasing an over-the-
counter test. However, they're not always accurate, warns Ginger Hultin, M.S.,
R.D.N., spokesperson for the Academy of Nutrition and Dietetics.
“They sell testing strips for urine, though those can get false reads for a number of
reasons, like hydration levels,” she previously told Men's Health.
So, in short, it's kind of tough to tell. You just have to stick to your macros and
hope the number on the scale drops.
What are the bene몭its of the keto diet?
the risk of and alleviate symptoms related to heart disease, diabetes, and a whole
host of other challenging conditions.
Well, you can lose weight on keto. And maintaining a healthy weight can reduce
6. ETHAN CALABRESE
When it comes to weight loss, "there is no question that ketosis does work in the
short term," Konstantinos Spaniolas, M.D., associate director of the Stony Brook
Metabolic and Bariatric Weight Loss Center in New York.
Anecdotally, plenty of men have told Men's Health that the keto diet helped them
lose large amounts of weight. According to Spaniolas, keto helps with weight loss
by reducing cravings.
Some studies show that keto may lower blood sugar for people with type 2
diabetes, but there is not enough long-term research to determine whether it’s safe
and eﬀective for diabetics.
Also, side note, although studies have shown that the keto diet can reduce seizures
for children with epilepsy, there is no evidence indicating that keto helps with
other brain disorders or improves mental cognition, according to Harvard Health
7. So, in the short term, yes, a keto diet can help you lose weight, which may reduce
your risk of disease—but more indirectly than directly. But what about in the long
Does the keto diet work for long-term
It's still too soon to tell. In fact, the rapid weight loss which occurs at the start of a
keto diet may not be fat loss at all.
“Early weight loss at the beginning of the Keto diet is likely related to ﬂuctuations
in ﬂuid,” says Ashley Harpst, R.D., a sports dietitian and the owner of Go For the
Gold Nutrition in San Diego. “Three to four ounces of water is retained for every 1
gram of carbohydrate stored as glycogen in the muscles to use for energy.” So, as
your glycogen stores are depleted and you enter ketosis, there’s less water in your
body as well.
There's also no long-term data on ketogenic diets versus other diets. In a 2015
Italian study, those on a ketosis diet lost 26 pounds in three months. About half of
the participants stayed on the diet for a year but lost little additional weight in the
next nine months. People in a 2014 Spanish study who followed a very-low-calorie
ketogenic diet lost an average of 44 pounds in a year—but a third of them
dropped out, possibly because it was too hard to maintain.
Another study, published in 2020 in The BMJ, analyzed the results from 121
previously conducted clinical trials that looked at the eﬀectiveness of various diets
(low-fat, low-carb, low-calorie, etc.) for weight loss and lowering markers of
cardiovascular disease risk, like blood pressure and LDL cholesterol. Based on data
from nearly 22,000 adults, the researchers found that while all of these diets led to
weight loss and improvements in cardiovascular health markers in the ﬁrst six
months, virtually all of those beneﬁts had disappeared at the one year mark.
The bottom line: Keto (and any other diet) may lead to weight loss and improved
health in the ﬁrst several months, but even if you’re able to stay on the diet for
longer, those beneﬁts will likely disappear after about a year.
8. Do ketone supplements work?
While it is possible to elevate your ketones by taking them, “without the low-carb
stimulus, there is no net increase in ketone production, no decrease in insulin, and
no net increase in fat oxidation,” says Volek.
So don’t trust trainers or “body hackers” who say that you can induce ketosis
quickly via a pill, powder, or potion—without changing your diet.
What are the side eﬀects of the keto
There are a few. Let's hit them one at a time.
People who begin the diet often develop “Keto Flu,” as their bodies get accustomed
to eating fewer carbs. During this time you may experience headaches, nausea,
fogginess, muscle cramps and fatigue. Symptoms last about a week, but staying
hydrated and getting ample sleep will help with cramps and exhaustion.
Aside from Keto Flu, you may notice a few other unpleasant side eﬀects. Acetone
—yes, the ingredient in nail polish remover—is one of the compounds found in
ketones, so your breath may be stinkier than normal. Pooping may be diﬃcult
since cutting carbs will lower ﬁber intake, but a ﬁber supplement will help keep
9. OMAHA STEAKS
There’s also the risk of nutrient deﬁciencies when you’re on the keto diet. “An
individual who cuts out whole grains may become deﬁcient in vitamin B1
(thiamine) and B3 (niacin),” Harpst says.
These essential vitamins are added to grain products through fortiﬁcation, as it’s
tough to eat enough of them through food alone, and deﬁciencies can lead to
adverse health eﬀects. Iron and vitamin B9 (folate) are also added to grains, and
while it’s relatively easy to get enough iron by eating animal products, eliminating
grains can lead to folate deﬁciencies, as well. (This is particularly concerning for
women who may become pregnant, as folate is essential for neural tube
development in the ﬁrst month of pregnancy, before most women even realize
And, while there’s not enough long-term research on keto diets speciﬁcally, a 2021
review published in Frontiers in Nutrition concluded that foods and nutrients
10. typically consumed at higher than average levels on the keto diet (namely red
meat, processed meat, and saturated fat) are linked to an increased risk of kidney
disease, heart disease, cancer, diabetes and Alzheimers, whereas restricted foods
like fruits, vegetables, legumes, and whole grains are associated with lowered risk
of these same conditions. “Current evidence suggests that for most individuals, the
risks of such diets outweigh the beneﬁts,” the authors state.
Is the ketogenic diet for you?
This may sound like a cop out, but the best diet is the one you stick with. For
Volek, who’s been following an ultra-low-carb diet for two decades, it works.
If you can’t stick to it, then it probably won’t.
"This is the problem I have with all of these fad diets," registered dietitian Andy
Yurechko, M.S., R.D., of Augusta University Medical Center in Georgia, previously
told Men's Health. "A healthier type of diet is something you can do every day of
Since maintaining ketosis requires strict carb counting, this diet works best for
people who are diligent. And, it’s probably not a good idea for athletes or avid
gym-goers to do the keto diet long-term.
“There is no conclusive research to support any athletic performance beneﬁt [of
keto],” Harpst says. “Research continues to show that training on a low carb diet
impairs intensity and decreases endurance, recovery and cognitive function.”
It can also impair muscle strength, she says, since carbohydrates are muscle’s
preferred energy source during workouts, and because muscle synthesis (AKA,
repairing and building muscle in order to get stronger) requires both protein and
Keto diet tips
Still, there are a few healthy habits from the keto diet that are easy to adopt:
11. GETTY IMAGES
Instead of thinking about the total carbs you’re eating, assess what those carbs
provide to you. Do the majority of your carbs come from fruits, vegetables, whole
grains, and legumes, all of which deliver loads of and health-supporting ﬁber and
antioxidants? Fantastic. Or are you consuming them mostly in the form of added
sugars (cookies, candy, soda) or reﬁned ﬂour? It’s ﬁne to enjoy your favorite sweet
treats and processed foods sometimes, but the bulk of your carbs should come
from whole food sources.
12. The ketogenic diet may seem like the Jekyll to the Hyde-like low-fat craze of the
1990s. The bulk of current research ﬁnds that the middle ground between the two
extremes is more beneﬁcial for overall health. Make it easy for yourself: Eat at
least two servings a week of fatty ﬁsh (salmon, sardines, mackerel) and cook with
a variety of quality fats (olive oil, canola oil, avocado oil) throughout the week.
Leafy vegetables are loaded with nutrients and they're keto-friendly. There’s kale,
spinach, bok choy, Swiss chard, collards, watercress, mizuna, and arugula. Dig in.
Oh, and you might be wondering—how’d things turn out with the bacon beaus?
Their experiment worked until life changed. They had a kid. They made a big
move. They stopped the diet. “It was too hard to maintain,” she told me. Proof that
all the bacon you can handle even grows boring after a while.
13. MELISSA MATTHEWS HEALTH WRITER
Melissa Matthews is the Health Writer at Men's Health, covering the latest in food, nutrition, and
Christine Byrne, MPH, RD, LDN, is a registered dietitian and the owner of Christine Byrne
Nutrition, a private practice serving clients in Raleigh, NC, and virtually across the country. She
specializes in eating disorders and disordered eating, and takes a weight-inclusive approach to
health. A longtime journalist, she has worked as a food editor at BuzzFeed and Self, and her
writing has appeared in dozens of national media outlets, including Outside, HuﬀPost, EatingWell,
Food Network, Glamour, Bon Appetit, Health, and more.
CHRIS MOHR, PH.D., R.D.
Chris Mohr, PhD, RD is the co-owner of Mohr Results, Inc (MohrResults.com) a well-being