The Longer You’re Overweight, the Greater Your Risk of Cancer

cancer

Story at-a-glance -

  • For every decade a woman is obese, her odds of developing breast, endometrial, colon or kidney cancer rises by 10 percent. For each decade she’s overweight, her risk rises by 7 percent
  • Excess body weight is responsible for about 25 percent of the relative contribution to cancer incidence, second only to smoking, and is a contributing factor in 20 percent of all cancer deaths in the U.S.
  • Lifestyle strategies that can slash your risk of cancer include nutritional ketosis (a diet high in healthy fat, low in net carbs), peak fasting and exercise — all of which boost your mitochondrial health

By Dr. Mercola

According to recent research, the longer a woman is overweight, the more likely she is to develop breast, endometrial, colon or kidney cancer.1 Obesity is indeed a known risk factor for cancer, so this finding in and of itself is not surprising.

Worldwide, obesity is responsible for an estimated 500,000 cancer cases each year,2 and according to the American Association for Cancer Research (AACR), excess body weight is responsible for about 25 percent of the relative contribution to cancer incidence, ranking second only to smoking.3

When obesity is combined with other high-risk behaviors, such as a poor diet and lack of exercise, the relative contribution rises to 33 percent of all cancer cases in the U.S. What's new here is that the length of time spent being overweight also contributes to your overall risk. As reported by CBS News:4

"On average, the study found, the odds rose by 10 percent for every 10 years a woman had been obese. Similarly, they climbed by 7 percent for every decade she'd been overweight."

How Excess Weight Contributes to Cancer

Obesity can raise your risk of cancer in several ways. Some cancers, especially breast and endometrial cancer, are sensitive to the female sex hormone estrogen, and fat cells produce an excess of this hormone.

This is also why obesity in young children is such a grave concern. By carrying excess weight (and excess estrogen) for many years, if not decades, they're at a significantly heightened risk of cancer as adults.

Obesity is also associated with elevated inflammation levels in your body, which can contribute to cancer growth. One of the basic reasons why nutritional ketosis works so well against cancer is because it drives your inflammation down to almost nothing.

A high-sugar diet, which tends to pack on the pounds, also feeds cancer by providing cancer cells with their preferred fuel. A healthy high-fat diet, on the other hand, tends to discourage cancer growth, as cancer cells lack the metabolic flexibility to use ketones derived from fat as fuel.

It is likely that the obesity represents an indirect marker for the true cause of the problem that contributes to both obesity and cancer, namely insulin resistance, which is also associated with leptin resistance and activation of the mTOR pathway.

By lowering your blood sugar levels and normalizing your insulin receptor sensitivity, exercise has a similar effect, as this too creates an environment less conducive to cancer growth.

Rising Obesity Rates Are Related to Misleading Health Advice

Obesity is the result of inappropriate lifestyle choices and, unfortunately, the U.S. government has done a terrible job at disseminating accurate information about diet and health.

It's one thing for corporations to put out misleading ads. After all, honesty is not in the self-interest of the processed food and beverage industry. It's another when the government falls in line with for-profit deception and becomes a propagator of corporate propaganda, yet this is exactly what has happened.

For example, conventional recommendations that drive public health in the wrong direction include the advice to:

Cut calories: Not all calories are created equal, and counting calories will not help you lose weight if you're consuming calories from unhealthy sources.

Choose no- or low-calorie foods: Substances like Splenda (sucralose) and Equal or Nutrasweet (aspartame) may have zero calories, but your body isn't fooled.

When it gets a "sweet" taste, it expects calories to follow, and when this doesn't occur, it leads to distortions in your biochemistry that promote weight gain instead.

Snack throughout the day to keep your blood sugar even: Mounting research suggests this constant grazing adapts your body to burn sugar as its primary fuel, which down-regulates enzymes that utilize and burn stored fat.

Biologically, your body simply isn't designed to run optimally when continuously fed, and studies show peak fasting (intermittent fasting) yields significant health benefits that go beyond mere weight loss. So you can snack regularly, but only within the restricted eating window of six to eight hours.

When you do peak fasting, the resulting metabolic changes stimulate a natural cleansing process known as autophagy (or mitophagy in the case of mitochondrial autophagy), in which your body detoxifies and rids itself of damaged cells that may contribute to disease, including cancer.

Another mechanism by which peak fasting benefits your health is by stimulating your mitochondria to work more efficiently.

Peak fasting helps activate your mitochondria and promote their healthy function, and you simply cannot be healthy unless your mitochondria are functioning well.

Avoid saturated fat: The myth that saturated fat causes heart disease began as little more than a scientifically unsupported marketing strategy for Crisco cooking oil.

For optimal health, most people actually need anywhere from 50 to 80 percent of their diet as healthy fats, examples of which include organic, pastured egg yolks, raw nuts, avocados, coconut oil, MCT oil and real butter.

Healthy Lifestyle Strategies Promote Mitochondrial Health

Have you noticed that things that are inherently healthy for you do not simply address just one issue — they have multiple beneficial influences. This is in stark contrast to drugs, where a synthetic chemical forces your body to respond in a particular way, which can have significant adverse effects.

When it comes to healthy diet and lifestyle strategies such as exercise, one benefit feeds right into another, which feeds into a third, and so on down the line.

For example, swapping processed foods for real, minimally processed foods will not only aid weight loss efforts, it will also supply your body with nutrients it needs to optimize immune function and ward off disease.

The same can be said for intermittent fasting. By paying careful attention to the TIMING of your meals, you can improve your weight and cut your risk of serious diseases like cancer.

When you look at strategies that help keep you healthy, one of the common denominators running through all of them is that they promote mitochondrial function. Mitochondria are tiny organelles, originally thought to be derived from bacteria.

Red blood cells and skin cells have very little to none, while germ cells have 100,000, but most cells have one to 2,000 of them. They're the primary source of energy production in the form of ATP for your body.

Since mitochondrial function is core to optimizing your health, optimizing mitochondrial function — and preventing mitochondrial dysfunction by making sure you get all the right nutrients and precursors your mitochondria need — is extremely important for disease prevention, including cancer.

In fact, one of the universal characteristics of cancer cells is they have serious mitochondrial dysfunction with radically decreased numbers of functional mitochondria. This is in part why your lifestyle can have such a significant impact on your cancer risk.

The Metabolic Theory of Cancer

Travis Christofferson is the author of "Tripping Over the Truth: The Return of the Metabolic Theory of Cancer Illuminates a New and Hopeful Path to a Cure." In this interview, Christofferson — who has a Pre-Medical undergraduate degree and a Master's degree in Materials Engineering and Science — reviews some of the details covered in his phenomenal book.

"When you look at cancer metabolically, the whole paradigm of therapy [changes]. You go from this targeted paradigm to all of a sudden targeting the metabolism," he says. "You're trying to restore mitochondria function. You're trying to increase mitochondrial numbers.

You can probably rescue some cells within a tumor and divert them back into living within the collective of the multicellular organism. They will revert to being normal. Some you can send over this tipping point. You can kill them through these various therapies metabolically. It's an interesting time. The paradigm of cancer is being turned therapeutically and our understanding of it."  

At the heart of the metabolic theory of cancer, you find two simple tenets that explain why nutritional ketosis — achieved through a diet high in healthy fats, moderate in protein and low in net carbs (total carbs minus fiber) — is so effective for driving down your cancer risk:

Cancer cells primarily burn glucose, which promotes inflammation and damage by generating high amounts of reactive oxygen species (ROS) — far more so than fat and ketones do when burned. Glucose by itself can also shift cells toward cancer by upregulating the expression of an enzyme called hexokinase II. Christofferson discusses this research in the interview.

Cancer cells cannot utilize fat for fuel whereas all healthy cells can, so by eliminating cancer cells' preferred fuel — glucose — and shifting your body toward burning fat as its primary fuel, cancer cells are starved while healthy cells are nourished. Since fats and ketones generate far fewer ROS when burned for energy, you also naturally suppress inflammation.

The Importance of Exercise

Exercise also boosts mitochondrial health by increasing the AMPK pathway. This in turn increases a low level of reactive oxygen species (ROS), which serve as important signaling molecules. In this case, they signal your body to make more mitochondria (mitochondrial biogenesis). Christofferson's book goes into this in great detail as well.

So, when you exercise, your body responds by creating more mitochondria through mitochondrial biogenesis to keep up with the heightened energy requirement. This is a very good thing; remember, cancer is characterized by a decrease in functional mitochondria, and increasing the numbers is part of effective cancer prevention. Aside from its effect on your mitochondria, exercise also decreases your cancer risk by:

Affecting other biological functions that have a direct influence on cancer, such as energy balance, immune function, antioxidant defense, DNA repair and hormone levels5

Decreasing your insulin resistance, which is a profoundly effective strategy to reduce your cancer risk, since a low sugar environment discourages the growth and spread of cancer cells

Improving blood circulation, driving more oxygen into your tissues and circulating immune cells in your blood. By improving blood flow to your liver, it also helps your body detoxify potentially harmful substances, including excess estrogen that may spur estrogen-sensitive cancers

Stimulating AMPK and SIRT1, which secondarily inhibits the mTOR pathway that is involved in aging and cancer. This in turn stimulates mitochondrial biogenesis and mitophagy, both of which are deadly to cancer

Exercise Is Potent Cancer Prevention

More than 100 epidemiologic studies investigating the role of exercise for cancer prevention have been published,6 and while the exact risk reduction varies from study to study, the literature consistently show that exercise helps reduce your risk of a variety of different cancers, and often to a significant degree.

For example, the bulk of the data shows that physically active people reduce their risk of colon cancer and breast cancer by 30 to 40 percent and 20 to 30 percent respectively. Here's a sampling of studies showing how, and to what degree, exercise may reduce your risk of cancer:

Cell Metabolism 20167 — Active mice experienced a 50 percent reduction in tumor growth compared to inactive mice, and the mechanism is thought to be related to the rush of adrenaline that occurs during high-intensity exercise.

Adrenaline helps circulate natural killer (NK) immune cells into tumors in the lung, liver and skin, where they go to work to kill off and eliminate cancerous cells. Importantly, an immune signaling molecule called interleukin-6 (IL-6), which is released by muscles during exercise, is what actually guides the NK cells into the tumors.

JAMA Oncology 20158,9 — Men who stayed fit in middle age had a 55 percent lower risk of lung cancer and a 44 percent lower risk of bowel cancer after the age of 65. High levels of cardiorespiratory fitness (CRF) in middle age also helped the men survive cancer, reducing their risk of dying from lung, bowel and prostate cancer by nearly one-third (32 percent).

Cancer Epidemiology, Biomarkers & Prevention 201510,11,12 — Women with a history of exercising for an average of 1.33 hours per week during their teen years had a 16 percent lower risk of dying from cancer, and a 15 percent lower all-cause mortality risk.

Those who were active as teens and kept up their exercise habit as adults had a 20 percent lower risk of death from all causes.

Journal of the National Cancer Institute 201513,14 — Aerobic exercise slowed the growth of breast cancer tumors in mice. By increasing tissue oxygenation, it also improved the effectiveness of chemotherapy.

Journal of Physical Activity and Health 201415 — A systematic review of seven cohort studies and 14 case-control studies found that physical activity reduces the risk of breast cancer, particularly in post-menopausal women.

International Liver Congress 201316 — Mice who exercised on a motorized treadmill for an hour each day, five days a week for 32 weeks, experienced fewer incidents of liver cancer (hepatocellular carcinoma) than sedentary mice.

Integrative Biology of Exercise meeting in 201217 — Exercise was shown to alter T cells to a more effective disease-fighting form, called "naïve" T cells, which boosts the ability of your immune system to fight emerging and existing cancer cells. This helps explain why exercise is beneficial both for cancer prevention and treatment.

Cancer Epidemiology Biomarkers & Prevention 200918Weight training cut men's risk of dying from cancer by 40 percent.

Cancer Causes Control 201019 — In women, strenuous activity at age 12 was associated with a reduced risk for breast cancer during pre- and post-menopause. Women who had engaged in moderate exercise during adulthood also had a significantly reduced risk of post-menopausal tumors.

American Journal of Public Health 201020 — Women who were active at home during the day, engaging in heavy lifting or carrying rather than mostly sitting, had a 38 percent reduced risk of invasive breast cancers.

JAMA 200521 — Breast cancer patients who exercised moderately for three to five hours a week lowered their odds of dying from cancer by about half, compared to sedentary patients.

Develop an Anti-Cancer Lifestyle

Obesity or insulin resistance is not the only risk factor for cancer, but it's a significant one. According to a position statement by the American Society of Clinical Oncology (ASCO), published in November, 2014, obesity is "quickly overtaking tobacco as the leading preventable cause of cancer."22 The Cancer Society also warns that obesity is a contributing factor in about 20 percent of all cancer deaths in the U.S.23

Fortunately, by addressing your diet and exercise, you can effectively lose weight and significantly reduce your risk of cancer — again, not just because you've lost weight, but because these strategies produce such a wide array of health-promoting effects. High on this list of beneficial effects is improved mitochondrial function and increased mitochondrial numbers.

For a more comprehensive list of guidelines for preventing both obesity and cancer, please refer to my previous article, "Obesity Now Causes Half a Million Cancers a Year, Worldwide." To summarize the points discussed above, strategies that will help you lose weight and slash your cancer risk include:

Switching to a ketogenic diet consisting of real, whole foods, high in healthy fats, moderate in high-quality protein and low in net carbohydrates (total carbs minus fiber). My updated Nutrition Plan can help you implement this type of diet in a controlled step-by-step fashion

Peak fasting

Regular exercise. Ideally you'll want to establish a comprehensive exercise program that includes high-intensity exercises and strength training, both of which have been shown to be of particular benefit for cancer prevention. If you need help to get started, check out my Fitness Plan

Regular and consistent non-exercise activity. While not discussed above, also consider sitting less and walking more. Aim for about 7,000 to 10,000 steps (or about an hour-long walk) per day and, if you can, limit your sitting to three hours a day or less, as the mere act of standing triggers beneficial changes in your biology

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