Better Nutrition March 2019

THE KETO THEORY
The keto diet changes metabolism by
shifting the human body’s fuel source
from blood glucose to ketones, chemicals
the liver makes when fat is burned to
generate energy. A perfectly healthy
human body could switch from one
fuel to the other as needed, much like a
hybrid car that uses either gas or electrical
power. However, the large amount of
carbohydrates that most people eat has
broken that switch, blocking fat from
being used as an energy source. The keto
diet forces the switch to turn on.
“You’re burning fat, which is in your
diet, but you’re also opening up pathways
that allow you to eat yourself—you
can liberate and mobilize fat, and your
brain senses that energy,” says Dominic
D’Agostino, PhD, a neuroscientist at
the University of South Florida who
has been researching keto diets and
supplements for over 10 years. “If you’re
on a really high-carbohydrate diet and
you go four or five hours without food,”
he adds, “your brain senses an energetic
crisis because it doesn’t have quick or
easy access to the fat.” If it did, there
wouldn’t be a problem.
Fat burning and keto production
are also triggered by fasting, which
is why people can survive without
food for weeks. Intense or prolonged
exercise can also trigger temporary
ketone production.
WHY KETO TRIGGERS
WEIGHT LOSS
Scores of dramatic before-and-after
photos, shared online by keto adherents,
might give you the idea that there’s
something magical about eating a lot
of fat. But this isn’t why the keto diet
works. “It helps you lose weight, but it
does it by calorie restriction, because it
helps you regulate your appetite,” says
D’Agostino. “It’s really changing brain
chemistry,” he adds. “Instead of your
appetite controlling you, the diet allows
you to control your appetite, to moderate
your intake, and to really control what
you eat.”
Keto Benefits Beyond Weight Loss
The keto diet originated in 1921 as a treatment for type 1 diabetes (before the
invention of diabetes drugs) and seizures among children with epilepsy. Since then,
studies have found that it may assist in the treatment of certain diseases, including:
Type 2 diabetes
Prediabetes
Seizure disorders
Acne and eczema
Polycystic ovary
syndrome (PCOS)
Cancer
Amyotrophic lateral
sclerosis (ALS)
Alzheimer’s disease
Traumatic brain
injury
KETO DIET BASICS
The carb content of keto diets is typically counted as net carbs: the amount of total
carbs in a food minus its fiber content. Total net carbs per day range between 20 and
50 grams, much lower than the typical American diet, which contains between
200 and 300 grams of total carbs.
No one officially tracks the nation’s net carb consumption, but it’s estimated that
we eat an average of 15 grams of fiber daily. Subtracting the fiber from total carbs,
average daily net carbs would be around 185 to 285 grams—dramatically higher
than keto diet levels.
The carb calories are replaced mostly by fat, as in healthy fat. Protein levels don’t
dramatically change and shouldn’t be too high, as too much protein can prevent fat
burning. Although we don’t usually turn protein into blood glucose, it can happen
on a low-carb, high-protein diet.
The proportion of fat calories in a keto diet can vary from 60–75 percent. Protein
would be about 20 percent, and carbs would make up the rest. This, says Steelsmith,
is how a strict, very low-carb keto diet would compare with a standard American diet:
Digestive disorders
Autoimmune
diseases
Gout
Fatty liver disease
In addition, because the keto diet lowers unhealthy levels of blood glucose, it may
lower risk for atherosclerosis, heart disease, and stroke.
Standard American Diet
Fat
34%
Approximate % of Calories
Keto Diet
Protein
16% Protein
20%
Carbs
50%
Fat
75%
Carbs 5%
36 • MARCH 2019