Some breast cancer patients and survivors may want to consider avoiding certain diets, date from mice studies has cautioned.
University of Utah researchers found that triple-negative breast cancer (TNBC)—an aggressive type of invasive breast cancer—is fueled by lipids and that these fatty acids are a key feature of obesity that promote tumor growth.
Experiments with preclinical mouse models suggest that those affected by this type of breast cancer and who have obesity could benefit from lipid-lowering therapies and steering clear of high-fat weight loss regimens—like the keto diet.
In the U.S., triple-negative breast cancer accounts for about 10–15 percent of all breast cancers.
"We need to be clear that our study was conducted in mouse models and patients should consult their physician before considering any use of lipid lowering medications or change in diet. Rigorous human data on the use of keto or high fat diets in cancer treatment/prevention is lacking," researchers at Utah's Huntsman Cancer Institute Keren Hilgendorf, Amandine Chaix and Greg Ducker told Newsweek.
"Our mouse model data suggests that keto diets are detrimental to fighting breast cancer, but we acknowledge that keto diets have shown promise in other cancers."
The ketogenic diet—on which more generally there has been conflicting research—is a low-carb, high-fat and moderate-protein diet intended to send the body into "ketosis."
While typically the body uses glucose from carbs as fuel, when deprived of this main source of energy it starts to take glucose from the liver and muscles. After a few days, when these reserves are all used up, the body turns to stored fat and the liver converts the fat into ketones.
It includes foods like fish, meat and poultry; non-starchy vegetables; avocados; berries; nuts and seeds; eggs; olive oil; high-cocoa chocolate and high-fat dairy.
In terms of why people with obesity and this breast cancer type may want to be aware of this type of high-fat diet, Hilgendorf explained in a statement that “the key here is that people have underestimated the importance of fats and lipids in the all-encompassing term that is obesity.
“But our study shows that breast cancer cells are really addicted to lipids and the abundance of lipids in patients with obesity is one of the reasons that breast cancer is more prevalent and more aggressive in these patients.”
The team conducted their research by analyzing mouse models on high-fat diets.
They also used models engineered to have hyperlipidemia (a high amount of lipids in the blood, commonly associated with obesity) without other key markers of obesity like high glucose and insulin levels. In these models, the high lipids alone accelerated tumor growth.
“The idea is that lipids, which form the surface membrane of the cell, are like building blocks,” Chaix said. “If a cell receives the signal to proliferate [increase or multiply] and more building blocks are available, the tumor is going to grow more easily. We see that a high amount of lipids enables this proliferation.”
In this model, lowering the amount of lipids in the presence of high glucose and insulin levels slowed down the cancer cell growth.
The studies are at an early stage and mice have key metabolic differences to humans. But if the link is proved in future studies this could lead to improved therapies and diet recommendations to slow cancer growth, according to the team.
“We think this has therapeutic implications, because if you could just lower the lipids—which we already know how to do in patients, for example, with lipid-lowering medication—that could be a way to decelerate breast cancer growth. If we can target these high levels of fat in the blood, the cancer suffers because the lipids are no longer feeding the cancer,” said Hilgendorf.
“But while our results in mice were striking, there are clear limitations in directly projecting these findings onto human patients. More research using human samples and patients will be necessary to confirm our hypotheses.”
Clinicians already recommend some breast cancer patients with obesity to lose weight to minimize any increased risk factors of cancer spread or disease recurrence, but this research could pave the way to better evidence-based guidelines for the best diets.
While some patients may turn to certain diets with good intentions, not all may bring them health benefits overall, hence the need to consult with a doctor.
Next steps include preclinically evaluating how anti-lipid drugs could improve responses to chemotherapy and better understanding how the lipids feed cancer cells, the researchers said. This will include determining how the results translate to humans.
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Reference
Vieira, R. F., Sanchez, S. R., Arumugam, M., Mower, P. D., Curtin, M. C., Jackson, A. E., Gallop, M. R., Wright, J., Bowles, A., Ducker, G. S., Hilgendorf, K. I., & Chaix, A. (2025). Hyperlipidemia drives tumor growth in a mouse model of obesity-accelerated breast cancer growth. Cancer & Metabolism, 13(1), 39. https://doi.org/10.1186/s40170-025-00407-0
