These keto diet side effects are seriously strange
This article was medically
reviewed by Rachel Lustgarten, R.D., C.D.N., a clinical dietitian and member of
the Prevention Medical Review Board.
The keto diet has blown up as an
ultra-low carb eating plan that can help you drop pounds fast—but its effects
on your body go beyond weight loss.
A typical keto diet is comprised
of 80% fat, 15% protein, and a mere 5% of calories from carbohydrates. If you
consume 2,000 calories a day, that means just 100 of them are coming from
carbs—including healthy carbs like fruits and vegetables. When you eat this
way, it triggers ketosis, which means your body has burned through all its
carbs and needs to begin burning fat for energy.
It’s true: Following a strict high-fat,
low-carb regimen can help move the number on the scale, but there might be some
other keto diet side effects that you aren’t aware of. Some of them are
positives, but a few could be unpleasant—or even dangerous. Here’s what you
should know about keto diet dangers before you decide to try it for yourself.
You might get hit with the “keto flu”
Keto flu is a real thing. Cutting
your carbs to the bone and going into a state of ketosis (where your body burns
fat for energy) can bring on a cluster of uncomfortable symptoms, such as
headaches, fatigue, muscle aches, nausea, and diarrhea. The side effects are
the result of your body transitioning to using fat as its primary source of
energy instead of carbs, explains Kristen Mancinelli, M.S., R.D.N., author of
The Ketogenic Diet. Once it adapts to the new fuel source (usually within a
week or two), you’ll start to feel better.
You may feel moody
When you're on a low carb diet
you may not be getting the carbohydrates needed to produce serotonin, a brain
chemical that helps regulate mood, as well as sleep and appetite—two other
factors that can mess with your disposition, says Laura Iu, R.D., registered
dietitian and nutrition therapist certified intuitive eating counselor based in
New York City.
Your eating behaviors could change
Cutting out carbs can cause the
brain to release a chemical calledneuropeptide-Y (NPY), which tells the body
that we need carbs; when we don't get those carbohydrates our body needs, this
chemical builds up and can intensify cravings, which can increase the risk of
developing disordered eating patterns like binge eating, says Iu. "It has
nothing to do with not having enough 'will power,' it's more to do with the
body's biological response to deprivation," she says.
Initial weight loss could come back
The keto diet is notorious for
delivering a quick initial slim down. That’s because carbs hold on to more
water than protein or fat, says Becky Kerkenbush, R.D., a clinical dietitian at
Watertown Regional Medical Center. So when you stop eating them, all that extra
H2O gets released through urination. As a result, the scale might read a few
pounds lower, and you may look a bit leaner.
That first drop might be mostly
water weight. But research suggests that the keto diet is good for fat loss,
too. An Italian study of nearly 20,000 obese adults found that participants who
ate keto lost around 12 pounds in 25 days. However, there aren’t many studies
looking at whether the pounds will stay off long-term, researchers note. Most
people find it tough to stick with such a strict eating plan, and if you veer
off your diet, the pounds can easily pile back on.
Or, you could experience diarrhea
"When we eat foods with fat,
our liver releases bile into the digestive system to help break it down.
Following a high fat diet like keto means that the liver needs to release extra
bile—and bile is natural laxative, so too much can loosen stool and speed up
how fast it moves through your system, leading to diarrhea," says Iu.
There’s also a side effect called “keto breath”
When your body goes into ketosis,
it will start to produce by-products called ketones. This includes acetone—yes,
the same chemical found in nail polish remover, which your body actually
naturally makes on its own, according to a 2015 review of research. "One
of the ways ketones are released from the body is through exhaling, and breath
usually has a distinct odor that's different than the common bad breath
experienced when there’s a build up of bacteria in the mouth," says Iu.
You’ll probably be thirsty all the time
Don’t be surprised if you find
yourself parched while you’re on the keto diet. Excreting all that extra water
will likely cause a spike in thirst—so make it a point to drink up, Mancinelli
advises. There’s no hard and fast recommendation for how much water you should
be having on a keto diet. But in general, aim to drink enough so your urine is
clear or pale yellow. If it’s any darker, bump your intake.
...but your appetite won’t be as ravenous
Weight loss often means feeling
hungrier and fighting off more cravings, but that doesn’t always seem to be the
case when you go keto. People report less hunger and a diminished desire to eat
after adopting a ketogenic diet, according to an analysis of 26 studies.
Experts don’t fully understand why, but it’s thought that very low carb diets
could suppress the production of hunger hormones like ghrelin.
And your skin might clear up!
Plagued by pimples? You may start
to notice a difference in your skin on the keto diet, especially if you were a
former sugar addict. Consuming lots of empty carbs is linked to worse acne—in
part because these foods trigger inflammation and signal the release of
hormones that up the production of pore-clogging oils, according to a review
published in the Journal of the Academy of Nutrition and Dietetics. Some
findings suggest that curbing your carb intake could help solve these problems,
improving your skin as a result.
Plus, many say they feel less brain fog
It’s no secret that
carbs—especially refined ones like sugary cereals, white bread and pasta, or
sweet drinks—cause your blood sugar to spike and dip. So it makes sense that
eating less of them can help keep things nice and even. For healthy people,
this can translate to more steady energy, less brain fog, and fewer sugary
cravings, Mancinelli explains.
...but others say their brain fog actually gets worse
That makes sense, says Iu.
"Our brains need the right type of carbohydrates for energy, and someone
who is following a low carb diet may not have enough of these carbs, which can
contribute to brain fog and difficulty concentrating," she says.
Your A1C levels could even improve
If you have diabetes, better
blood sugar control could help lower your A1C levels—the measurement of glucose
in our blood—and even reduce the need for insulin, according to a scholarly
review of ketogenic diets. (Just don’t go off your meds without speaking to
your doctor first!)
The one important caveat: Eating
keto also ups the risk for diabetic ketoacidosis, a life-threatening condition
where fat gets broken down too fast and causes the blood to become acidic. It’s
much more common in people with type 1 diabetes, but if you have type two and
are eating keto, talk with your doctor about what you should be doing to
diminish your risk.
But your kidneys might get stressed
The kidneys play an important
role in metabolizing protein, and it’s possible that eating too much of the
nutrient can have a negative impact on kidney function. While ketogenic diets
are supposed to be much higher in fat than they are in protein, many keto
eaters make the mistake of loading up on lots of meat, Mancinelli says. The
result? You could end up eating way more protein than you actually need.
Here’s the tricky part: There’s
no definitive answer for how much protein you’d have to eat before you run into
trouble. “It really depends on how much protein a person is consuming versus
how much they need, as well as the health of their kidneys at baseline,” Hultin
says. That’s why it can be helpful to speak with a nutritionist or doctor who
can help you tailor your diet before going keto.
Your heart disease risk factors could change
Eating an ultra-low carb diet is
linked to a lower rate of obesity and type 2 diabetes, along with improved HDL
cholesterol, all of which can translate to a lower risk for heart disease.
But your heart health might
depend on what you actually eat. Research published in the New England Journal
of Medicine suggests that low-carb diets based mostly on plant sources of fat
and protein (like avocados or nuts) can lower heart disease risk by 30%. But
those benefits didn’t hold for people who ate mostly animal-based proteins and
fats. (Think: bacon, butter, and steak.)
Plus, the American Heart
Association says that going overboard on saturated fat—which can be easy to do
on a keto diet if you eat a lot of meat, butter, and cheese—can up your risk
for heart problems. While you’re on the keto diet, you should have your
cholesterol levels and heart health assessed by a doctor on a regular basis, Hultin
says.
