i8i You’ll be
surprised at how often you hear something like this, though you usually don’t
hear it directly. People will say things like, “That doesn’t sound right” or
“Eating too much fat is dangerous” or “Epidemiological studies show that
[insert ominous thing here]” or “Look at what happened to Atkins on a low-carb
diet.” Sometimes, they’re right. The Standard American Diet [SAD] is definitely
too high in fat, especially saturated and trans. It is not especially
salubrious, and the extra fat (surprise) is usually stored. When your brain
runs on ketones rather than glucose, though, the fat isn’t stored. It’s used to
feed your brain and muscles. The key here is that you have to stay in ketosis.
You cannot use both glucose and ketones. Your body will opt for the glucose.
Unless you are basically using the glucose as soon as it goes in, your liver is
going to start storing the glucose and using it instead of the fat. You’re
going to have problems if you eat high fat and high carb.
So, they
ask, what stupid magazine or blog did you read all this crap on? I’m glad you
asked. While I did initially read about it on more general sites, I wound up
doing some of my own research as well. (Thanks, Google Scholar!) Most of the
existing studies deal with mice, but there was one of particular interest. This
was an observational study rather than an RCT, so it is not perfect; however,
the results are enlightening.
Essentially,
the trial followed a group of people who were using ketogenic diets to treat
their epilepsy. (Ketogenic diets have long been used to significantly decrease
the number of seizures that patients have when drug treatments are not
effective.) The study spanned 5 years and studied markers like body
composition, body fat percentage, bone minerals, [and so on]. The conclusions
were that the ketogenic diet did not have an appreciable negative effect on any
of the markers. It just cut the number of seizures in half. Unless you believe
that epilepsy somehow has a protective effect against fat accumulation in a
high-fat, low-carbohydrate diet, then this study indicates that a ketogenic
diet in and of itself is not inherently harmful.
Another
group that indicates this is the Inuit. They eat a ton of fat, mostly in the
form of blubber, and a very, very low-carbohydrate diet. Still, they tend to be
reasonably healthy.
Now, any
idiot can find a study, particularly an observational study, showing that diets
higher in fat tend to be associated with poorer health. The problem they have
is the same problem that most observational studies have: it’s next to
impossible to isolate single characteristics. The observational studies don’t
have much of anything to say about carbohydrate intake, or whether or not the
people tend to listen to their doctors when making choices about what to do.
It’s like many of the other observational studies that have returned results
that did not hold up in random-controlled trials: something else caused the
results. In at least some cases, researchers speculate that a.) people who
adopt one habit said to be healthy (such as eating less fat or eating
breakfast) are more likely to adopt other habits said to be healthy (such as
eating whole foods, not smoking, limiting alcohol, and getting regular
exercise), and b.) one of the latter habits is more likely to be responsible
for the health improvements than is one of the former.
Additionally,
recent studies, including random-controlled trials and meta-studies have failed
to replicate many of the supposed problems associated with higher fat
consumption, particularly when that is coupled with other healthy habits. In
fact, some studies have shown the opposite effect.
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