‘Keto’ Diet May Ease Cushing’s Symptoms, but Delay Diagnosis

Researchers describe case of a man who switched diets to lose weight

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Eggs, a chicken and drumsticks are shown, representing a ketogenic diet.

A young man switched his standard diet to a ketogenic, or “keto,” diet that’s low in carbohydrates and high in fats to lose weight, and saw some of his symptoms of Cushing’s disease ease, according to a new report.

But he wasn’t diagnosed until his symptoms came back or worsened over time, suggesting that a special diet may mask a disease’s symptoms to a point where it could delay or prevent a diagnosis.

“Diseases typically associated with poor lifestyle choices, like obesity and hypertension [high blood pressure], can often have alternative causes,” the researchers wrote. “Assuming that they are due to poor dietary adherence, can allow them to go undiagnosed.”

The report, “Ketogenic Diet Initially Masks Symptoms of Hypercortisolism in Cushing’s Disease,” was published in Metabolites.

Cushing’s occurs when the body has too much of a hormone called cortisol. This condition, called hypercortisolism, results in symptoms such as weight gain and fat accumulation, fragile skin, and high blood pressure.

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Masking Cushing’s with ketogenic diet

When paired with other treatments, a special diet that’s low in carbohydrates can help limit or counteract some of these symptoms.

A research team in the U.S. described the case of an Asian man in his 30s who saw some of his symptoms ease with the help of a ketogenic diet that limits the amount of carbohydrates (or “carbs”) eaten in a day to less than 30 grams, about the amount present in one medium ripe banana or two tablespoons of white sugar.

The man had a history of easy bruising, blood in urine (hematuria), headache, and high blood pressure. He also had excessive amounts of fat around the waist (central obesity). In 2015, he was at his heaviest weight at 179 pounds. His body mass index, a measure of body fat, placed him within the overweight range.

He ate a standard American diet and was active. A typical standard American diet includes a high intake of pre-packaged (processed) foods, refined grains, and high-fat dairy products.

Diseases typically associated with poor lifestyle choices, like obesity and hypertension [high blood pressure], can often have alternative causes. Assuming that they are due to poor dietary adherence, can allow them to go undiagnosed.

“He ate a diet of vegetables, fruits and carbohydrates, but he was not able to lose weight,” the researchers wrote.

To lose weight, the man switched to a ketogenic diet where he ate “green leafy vegetables, low carb fruits, fish, poultry, beef and dairy products.” This caused him to lose about 35 lbs over 1.5 years.

He later switched to a carnivore diet, a type of ketogenic diet that consisted of “a variety of different meats, poultry, fish and eggs,” but the switch didn’t help him lose any more weight. Despite this, his waist looked thinner, and his blood levels of sugar, cholesterol, and triglycerides (a type of fat) were within the normal range.

But during 2021, the man had episodes of high blood pressure that recurred despite treatment with blood pressure-lowering medications and a recommendation for a low-salt diet.

“The patient reported strict adherence to his carnivore diet by sharing his well-documented meals on his social media accounts,” the researchers wrote.

Reaching a Cushing’s diagnosis

A physical examination revealed a rounded (“moon”) face and stretch marks around the waist. This led doctors to suspect he might have Cushing’s.

Laboratory testing revealed he had higher than normal cortisol levels in the saliva late at night when they are normally low. They failed to drop in response to a low-dose dexamethasone test, confirming hypercortisolism.

Dexamethasone is a medication that cuts short the production of cortisol, lowering its levels in the blood of healthy people, but not in those with Cushing’s.

In many people with Cushing’s, the brain’s pituitary gland makes too much adrenocorticotropic hormone (ACTH), a hormone that drives the adrenal glands to produce cortisol. While the man’s ACTH blood levels fell within the normal range, they were suggestive of ACTH-dependent Cushing’s.

A brain MRI scan revealed a tiny benign tumor, or microadenoma, measuring about 4 mm in diameter as the possible source of the pituitary gland producing excessive amounts of ACTH. Based on these findings, doctors made a diagnosis of Cushing’s disease.

“This case serves as a reminder of the power of nutrition to address metabolic derangements and simultaneously as a reminder to diagnosticians to never rely on lack of dietary adherence as a reason for persistent metabolic symptoms,” the researchers wrote.

The man is scheduled to have surgery to remove the microadenoma, the first line of treatment for Cushing’s disease.