Thousands of people swear by the weight-loss benefits of a ketogenic (keto) diet, which is a high-fat, ultra-low-carbohydrate lifestyle that fools the body into a starvation state so it burns fat instead of sugar.
The keto diet also provides anti-inflammatory and immune boosts, and some say it’s even good for your state of mind because ketones are better brain fuel than glucose.
But diets must be sustainable to be effective, and there’s reason to believe that the keto diet’s long-term damage outweighs its short-term rewards.
“There isn’t enough science to back up the anecdotal benefits of the keto diet,” says Carey Shore, MS, RD, LD, wellness coach and program coordinator at Methodist Dallas and Methodist Richardson Medical Centers. “The downsides are also so significant, they outweigh any potential rewards.”
Shore ticks of a laundry list of keto’s risks.
- Dieters may experience kidney damage and loss of renal function as the body processes excess protein.
- The keto diet can lead to poor digestion and acid reflux from having little to no fiber (most fruits and vegetables are a no-no) to help break down that food.
- People may have a decrease in bone mineral content.
- Kidney stones caused by higher levels of calcium in the urine can also affect dieters.
Worst of all, fat provides up to 90% of the calories in a keto diet. That extra saturated fat can cause your cholesterol to skyrocket, Shore says, so patients who were thrilled when the pounds melted off may get a surprise with their next health screening.
WHAT’S THE POTENTIAL REWARD?
If the risks don’t dissuade you, let’s focus for a moment on what rewards the keto diet promises.
First, here’s how it works: The keto diet essentially tricks your body by depriving its cells of blood sugar, their preferred fuel. To compensate for the missing glucose, your body believes it’s starving and converts stored fat into ketones, which serve as an alternative energy supply.
It can take up to four days for the body to fully shift to ketosis — and you’ll likely be starving the whole time. You’re also likely to lose weight fast when your body adjusts to a steady diet of meat, eggs, and fish.
But beware of the yo-yo effect that is common with so many diets but especially so with the keto diet.
“There is no value, in my mind, over short-term weight loss when that weight will most likely surge once a person is off of the diet,” Shore says.
BOOSTS TO IMMUNE, BRAIN HEALTH
Researchers have also found that ketosis lowers diabetes risk and inflammation throughout the body thanks to an immune system byproduct of burning all that fat: gamma delta T cells.
However, Shore warns, “People with diabetes who follow this plan will see a temporary drop in blood sugars, but it is short-lived and not sustainable. Even people with diabetes need some carbohydrates. There really isn’t enough science to back up the benefits in a meaningful way.”
Finally, brain health seems to benefit, with some research showing ketosis stabilizes the function of neurons and even encourages the growth of mitochondria, the power plants of the brain. The keto diet actually began as a treatment for epilepsy in the 1920s.
“There are no clinical applications for keto other than for epilepsy,” Shore notes.
BENEFITS CAN BE SHORT-LIVED
So how long do any of these benefits typically last? About a week, according to researchers at Yale University.
In a study published this year, scientists found that the fat-fueled mice they were studying stored all the excess fat they consumed to compensate for the suddenly missing carbohydrates. After several days on the diet, the mice became diabetic and obese.
The anti-inflammatory benefits also disappeared after a week as the protective T cells were stripped away. The researchers acknowledged that further study is needed, and only a clinical study of humans can truly settle the question of risk versus reward.
The bottom line: Speak with your doctor or a registered dietitian before adopting any new diet, but especially the keto diet.
Shore warns that there’s simply “no magic pill” for weight loss, and the keto diet is no different. She tells her clients to instead consider a diet that focuses on lean proteins, fruits and vegetables, and healthy fat, not the saturated kind that keto dieters often rely on.
“The keto diet is a great example of how fads should not supersede science,” she says. “Science takes more time to identify the potential harm of new approaches.”