A woman eats a meal at a table.Share on Pinterest
A new study looked at the impacts of the keto diet on cancer tumors. Drazen/Getty Images
  • New research on the keto diet finds it may help to slow the growth of tumors, but may also be linked to a wasting syndrome.
  • The study was done on rodents and found that those with colorectal or pancreatic cancer on the keto diet were more likely to develop cachexia, a wasting syndrome that causes loss of skeletal muscle and fat
  • The findings suggest that while some people with cancer may benefit from the keto diet, in others, it may come with more risks than benefits.

New research conducted in rodents has found that the ketogenic diet, also known as the keto diet, may help slow the growth of cancerous tumors.

At the same time, the high-fat, low-carbohydrate diet could contribute to cachexia, a wasting syndrome that causes loss of skeletal muscle and fat, that may shorten survival.

According to the report, published in Cell Metabolism on Monday, administering a steroid, like dexamethasone, alongside the keto diet may prevent the onset of cancer cachexia while continuing to slow tumor growth.

Prior research suggests that the keto diet can delay tumor progression and that cachexia is linked to poor prognosis, however, this is the first report to show that the keto diet can fuel cachexia, too.

The findings suggest that while some people with cancer may benefit from the keto diet, in others, it may come with more risks than benefits.

“The field had generally believed that a ketogenic diet could only be beneficial to cancer patients — most investigators thought through lowering circulating insulin, which accelerates tumor growth through multiple mechanisms — but the current findings would suggest that our recommendations need to be more nuanced,” Rachel J. Perry, PhD, an assistant professor of cellular & molecular physiology and internal medicine (endocrinology) at Yale School of Medicine, told Healthline.

The researchers evaluated the effects of a normal diet and low-carbohydrate, moderate-protein, high-fat ketogenic diet in mice with colorectal cancer and pancreatic cancer.

They found that tumor growth was significantly delayed in the mice that were fed the keto diet, suggesting that the diet had a powerful anti-tumor effect.

That said, the rodents on the keto diet were also more likely to develop cancer cachexia, losing large amounts of muscle mass and fat tissue, which shortened their survival compared to the mice with cancer who adhered to a normal diet.

The researchers also found that the mice eating the keto diet were unable to produce enough corticosterone, a hormone that helps regulate the diet’s health effects. As a result, the mice continued to lose weight.

“By eating keto (in mice), the cancer cells died faster, but the mice lost so much weight that they died earlier,” says Dana Ellis Hunnes, PhD, MPH, RD, a senior clinical dietitian at UCLA Medical Center, assistant professor at UCLA Fielding School of Public Health, and author of Recipe for Survival.

The researchers then injected these mice with corticosteroids and found that the tumors continued to shrink but the mice didn’t develop cachexia.

Looking forward, the researchers want to investigate corticosteroid timing and dosage to better understand how cancer therapies may work when administered alongside the keto diet.

“It does clearly make the case that we need evidence-based criteria for precision nutrition approaches in patients with cancer,” says Perry.

Previous research has shown that a low carbohydrate, or ketogenic diet, slows cancer growth.

According to Hunnes, depending on the type of cancer, the cells will feed on glucose.

“That’s their fuel of choice,” she said.

When you deprive these cancer cells of glucose, they die off as they don’t have the fuel and energy they need to grow.

That said, with certain cancers, the diet can accelerate the wasting disorder, cachexia.

According to Perry, the likelihood of cachexia does not entirely negate the potential benefits of the keto diet in people with cancer.

There are some cancer types in which cachexia is rare, she says, whereas other types of cancers are commonly associated with cachexia.

Perry says there is a time and place where the keto diet may be advisable for cancer patients, perhaps, in those with early-stage cancers along with cancer survivors.

“In others, such as those with metastatic cancer at risk for cachexia, it likely is not a good idea,” says Perry.

Certain cancers are catabolic, meaning people burn more calories and lose a lot of muscle and fat, says Hunnes.

“That’s really difficult to come back from,” Hunnes said, adding that it’s crucial for cancer patients to eat enough so they have the stamina to fight off cancer.

Many people with cancer are at risk of losing a lot of weight, so before starting a new diet, it’s crucial to work with a healthcare provider who can evaluate your health needs and develop a safe, effective eating plan.

“It will just be necessary to monitor for signs of cachexia (weight loss and, more specifically, muscle loss) and reconsider whether a ketogenic diet is the best option in patients with advanced cancer and/or indications of developing cachexia,” says Perry.

A new study suggests that the ketogenic diet may help slow the growth of cancerous tumors, however, it could also accelerate a wasting disorder called cachexia that may shorten survival. While the keto diet may be beneficial in some cancer patients, it may lead to a life-threatening amount of muscle and fat loss in others. More research is needed to understand how the keto diet may affect people with cancer, and how certain therapies, like corticosteroids, may enhance the diet’s benefits.