Study Says High-Calorie Foods Cause Cancer. Here’s What’s Wrong With That

While cancer may feel like a disease that strikes completely at random, research suggests that 30 to 40 percent of cancers are linked to diet and other modifiable lifestyle factors, like weight and exercise.^[1] In a recent special issue^[2] of the Journal of the Academy of Nutrition and Dietetics, nutritionists explored the connection between obesity, diet, and cancer to identify new areas of research for cancer prevention and treatment.

Prior to their research, the authors of one study highlighted in the issue believed obesity to be the prime culprit in cancer cases, and that diet and exercise would reduce cancer risk by helping people lose weight. While that is true (excess body fat increases the risk for 13 types of cancer), the authors also found that diet quality affects one’s cancer risk, even when you have a healthy body mass index (BMI). Specifically, they concluded that the more calorie-dense foods you eat, the greater your risk of cancer. While that may seem like a no-brainer, lumping together all high-calorie foods yields confusing and inaccurate nutrition advice to people who are worried about cancer.

Study suggests high energy dense (DED) diets increase cancer rates

In this previously published study, researchers analyzed the association between DED — the ratio of energy, or calories, to food weight — and obesity-associated cancers in 90,000 postmenopausal women. They concluded that consuming high-DED (high-fat and processed) foods resulted in a 10 percent increase in obesity-related cancer in normal-weight women.

“This finding suggests that weight management alone may not protect against obesity-related cancers if women favor a diet pattern indicative of high-energy density,” said co-leader of the Cancer Prevention and Control program at the University of Arizona Cancer Center, Dr. Cynthia A. Thomson

What is energy dense food?

Before you toss out your grass-fed butter, let’s get clear on what you need to know about DED food. High-energy-density foods are typically higher in fat and have a low water content. Foods like pizza, ice cream, and packaged bread products are all considered DED foods. Meanwhile, low-energy-density foods provide fewer calories per gram of food. Whole foods (vegetables, lean protein, even fruits and beans) are considered low-DED foods. They give you a ton of nutrients and are low in calories.

Based on this study, you’d assume you should limit all DED foods, right? What’s tricky about these findings is that they lump all energy-dense, high-fat foods together, suggesting that they’re all linked to cancer. However, there are plenty of high-calorie foods that aren’t unhealthy and, in fact, protect against cancer. It’s more likely that the certain types of fat spur cancer while others do not. The study also makes no distinction between high-sugar foods and high-fat foods. Sugar, in no form, is healthy, but the right kinds of fat offer all kinds of health benefits.

Indeed, Thompson admits, “High-DED foods may influence cancer etiology through other mechanisms, possibly because these foods promote greater inflammation, oxidative stress or higher insulin levels, all of which are factors that can contribute to a higher risk of cancer, particularly obesity-related cancers.” The key words to consider in this quote – “other mechanisms…can contribute to a higher risk of cancer.” It may have nothing to do with DED as it relates to high-fat foods. In other words, high insulin levels and inflammation come from oxidized fat — those found in processed vegetable oils like soybean, sunflower, corn, canola, cottonseed, and safflower oil; as well as fried and packaged foods, and charred meat. Sugar is also a culprit, and it’s found in just about every form of processed food you eat, from yogurt to granola bars. Indeed, this study^[3] reveals that it’s the oxidation of fat (through high heat) that leads to cancer, not the fat in and of itself.

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Other studies point to the high-fat keto diet for cancer treatment

Promising, preliminary research on ketogenic diets and cancer reveals that this high-fat, low-carb diet works as cancer therapy by starving cancer cells of glucose.^[4][5]  In one study the growth of human gastric cancer cells was delayed by a ketogenic diet supplemented with omega-3 fatty acids and medium-chain triglycerides.^[6] These keto-cancer cases demonstrate that healthy, high-fat foods don’t in fact promote cancer, and that this study’s analysis is woefully incomplete.  A more accurate assessment would be that junk food and processed food lead to cancer, which is what another recent study concluded. ^[7]

In a Bulletproof Radio (iTunes) podcast, Patricia Daly, a certified nutritionist/therapist who hacked her own cancer through a ketogenic diet, discussed the benefits of a high-fat keto diet and how it helped her beat the cancer odds. Specifically, she notes that the keto diet mimics fasting, which reduces cancerous inflammation and oxidative stress.

While the diet may be high in fat, it’s ridding the body of those culprits that lead to cancer in the first place. “Once blood sugars are low, then the cancer cells can’t be fed anymore. End of the story,” Daly explains.  “The ketogenic diet has in fact so many different pathways [to health]… I think there’s around 20 that we know of, but there’s at least as many that we probably don’t know of yet.”

Where should you go from here?

The research mentioned demonstrates that a high-fat, low-carb diet like the keto diet can delay cancer growth. However, it’s important to note that much of this research is still in pilot study form and warrants further study. As the authors of the special issue of the Journal of the Academy of Nutrition and Dietetic note, “Preclinical evidence suggests that dietary interventions, such as calorie restriction, intermittent fasting… and the ketogenic diet, have the potential to reverse some of these obesity-associated alterations [that drive cancer]; however, more clinical data are needed to confirm translation to human subjects.” Your takeaway: it’s never too soon to adopt a diet that will make you feel and perform at your best. However, if you’re a cancer patient who’s eager to try the keto diet, work with your oncologist, primary care physician, and dietitian as you make nutritional modifications.