What Is the Keto Diet (and Should You Try It)?

Mark Hyman, MD
October 29, 2018

A highly effective strategy for some, but not all, of us

Everybody’s doing the keto diet. It’s a cultural craze that’s captured our imagination.

But let’s remember that the ketogenic diet is a medical, or therapeutic, diet. So while it’s extremely beneficial for people with certain conditions, it’s not for everyone.

What do you eat on the keto diet?

The keto diet is essentially a high-fat diet — your meals are 70 or 80 percent fat; about 20 percent protein; and about 5 percent carbohydrate. It is not an Atkins high-protein diet.

The keto diet switches you from burning glucose (which carbs provide) to burning ketones (which fat produces) for energy. When you do this, interesting things happen:

• Your metabolism speeds up.
• Your hunger goes away.
• Your muscle mass increases.
• Your blood pressure and heart disease risk profile improve.

Why will eating fat help you burn fat?

Biology is smart. Historically, it allowed our bodies to adapt to times of abundance or scarcity by shifting from carbohydrate metabolism to fat metabolism.

When we found lots of wild fruit, we’d store the carbs as belly fat. Later, in lean times, we would use the fat as a backup source of fuel.

The key is this: Eating fat does not make your insulin go up, as eating carbs or protein does. So the keto diet does not spike your insulin, and you don’t store fat. Instead, you burn it, creating the ketones that give you an effective and efficient metabolic jolt.

Should you try the keto diet?

Here are a few reasons why you might think about doing the keto diet:

• Type 2 diabetes. One study found that being on the keto diet for one year reversed diabetes for up to 60 percent of participants. With an average weight loss of 30 pounds, they dramatically reduced or eliminated their need for insulin and no longer needed oral hypoglycemic drugs. The keto diet is also easier to sustain than the calorie-restricted diet or the protein-sparing modified fast.
• Morbid obesity. If your body mass index is over 40 — or if you have insulin resistance without type 2 diabetes — the keto diet can be very helpful as well. It can be used as a short-term strategy to reset your metabolism; you don’t have to be on it forever.

Clearly, the ketogenic diet is the standard of care for treatment-resistant epilepsy. But we’re also seeing its benefits in other neurological conditions. Research suggests the keto diet can bring improvements for those with Alzheimer’s disease; autism; or brain cancers such as glioblastoma.

So the keto diet can be a powerful intervention. People with type 2 diabetes and or/morbid obesity can do phenomenally well on it. (And the truth is, this describes many Americans; one in two of us are now are either prediabetic or type 2 diabetic, and 70 percent of us are overweight.)

But it’s vital to work with a doctor or health professional who can treat and follow you while you’re on the keto diet.

Who should not do the keto diet?

Our responses to the ketogenic diet are individualized. They’re based on our biology, our metabolism, our numbers and the way we feel.

Some people can sustain the diet for decades. Others don’t do well on it. For example, if I eat too much fat and too few carbs, I lose too much weight.

If you happen to be very thin, if you have an eating disorder, or if you have certain metabolic issues, the keto diet will also be risky for you. I would be very careful; check with your doctor before trying this diet.

We also don’t want to put kids on the keto diet, unless they have type 2 diabetes and are overweight. However, I would still check with your pediatrician.

Is the ketogenic diet safe long-term?

We still don’t have enough long-term data to say that the keto diet is effective and safe over 20 to 30 years. But if you’re overweight or diabetic, this diet can help get your system out of metabolic crisis and put it in a healthier state.

One thing I want to stress: It’s vital to eat real, whole, fresh foods when you’re on the keto diet. This includes non-starchy vegetables (the carbs from broccoli are pretty different from the carbs in cola). Frozen food is OK but should not be processed.

So whether you’re doing the keto diet, the Mediterranean diet or a low-fat diet, what matters most is the quality of the food you eat.