Studies have consistently found that people who are overweight or obese are also more likely to develop breast, pancreatic, kidney, colon, prostate, and gallbladder cancers. Studies have estimated that having a high body weight accounts for nearly a quarter of kidney and gallbladder cancers. Although obesity should be considered a disease in its own right, it is also one of the key risk factors for other chronic diseases together with smoking, high blood pressure and high blood cholesterol.
One study, using NCI Surveillance, Epidemiology, and End Results (SEER) data, estimated that in 2007 in the United States, about 34,000 new cases of cancer in men (4 percent) and 50,500 in women (7 percent) were due to obesity. The percentage of cases attributed to obesity varied widely for different cancer types but was as high as 40 percent for some cancers, particularly endometrial cancer and esophageal adenocarcinoma.
A projection of the future health and economic burden of obesity in 2030 estimated that continuation of existing trends in obesity will lead to about 500,000 additional cases of cancer in the United States by 2030. This analysis also found that if every adult reduced their BMI by 1 percent, which would be equivalent to a weight loss of roughly 1 kg (or 2.2 lbs) for an adult of average weight, this would prevent the increase in the number of cancer cases and actually result in the avoidance of about 100,000 new cases of cancer.
Several possible mechanisms have been suggested to explain the association of obesity with increased risk of certain cancers:
- Fat tissue produces excess amounts of estrogen, high levels of which have been associated with the risk of breast, endometrial, and some other cancers.
- Obese people often have increased levels of insulin and insulin-like growth factor-1 (IGF-1) in their blood (a condition known as hyperinsulinemia or insulin resistance), which may promote the development of certain tumors.
- Overweight and obesity lead to adverse metabolic effects on blood pressure, cholesterol, triglycerides and insulin resistance.
- Fat cells produce hormones, called adipokines, that may stimulate or inhibit cell growth. For example, leptin, which is more abundant in obese people, seems to promote cell proliferation, whereas adiponectin, which is less abundant in obese people, may have antiproliferative effects.
- Fat cells may also have direct and indirect effects on other tumor growth regulators, including mammalian target of rapamycin (mTOR) and AMP-activated protein kinase.
- Obese people often have chronic low-level, or “subacute,” inflammation, which has been associated with increased cancer risk.
The following diagrams (from one of the Death to Diabetes/Obesity Health Coaching Training Programs) depict the pathophysiology of obesity and the possible connections between obesity, diabetes, cancer, and other diseases.
Note: Chronic overweight and obesity contribute significantly to many complications, including osteoarthritis, a major cause of disability in adults.
Too much belly fat could increase the risk of cancer
The way that fat is distributed around the body can also affect the risk of cancer. Apple-shaped people who put on weight around their stomach may have higher risks than pear-shaped people who put on weight around their hips.
Scientists measure belly fat using either waist circumference (the length of tape that goes around your waist) or waist-to-hip ratio (how wide your waist is compared to your hips). Studies have found that people with larger waists or waist-to-hip ratios have higher risks of breast cancer, bowel cancer, kidney cancer, and pancreatic cancer.
Obesity may increase cancer risk by changing hormone levels
Scientists measure belly fat using either waist circumference (the length of tape that goes around your waist) or waist-to-hip ratio (how wide your waist is compared to your hips). Studies have found that people with larger waists or waist-to-hip ratios have higher risks of breast cancer, bowel cancer, kidney cancer, and pancreatic cancer.
Obesity may increase cancer risk by changing hormone levels
Obesity most likely increases the risk of cancer by raising levels of hormones such as estrogen and insulin.
In early life, estrogen is mainly produced by a woman’s ovaries, but this stops after menopause. Instead, fat in the body becomes the main source of estrogen and obese women have up to twice as much estrogen as women with a healthy weight. They also have lower levels of SHBG, or ‘sex hormone binding globulin’, which mops up estrogen in the body . This is almost certainly why obesity increases the risk of breast and womb cancers.
Obesity also increases levels of insulin in the body. It’s not clear how this could lead to cancer, although high insulin levels are a common feature of many cancers. High insulin levels could explain why being obese increases the risk of bowel, kidney and pancreatic cancer.
Obesity could also cause cancer through other means, including:
In early life, estrogen is mainly produced by a woman’s ovaries, but this stops after menopause. Instead, fat in the body becomes the main source of estrogen and obese women have up to twice as much estrogen as women with a healthy weight. They also have lower levels of SHBG, or ‘sex hormone binding globulin’, which mops up estrogen in the body . This is almost certainly why obesity increases the risk of breast and womb cancers.
Obesity also increases levels of insulin in the body. It’s not clear how this could lead to cancer, although high insulin levels are a common feature of many cancers. High insulin levels could explain why being obese increases the risk of bowel, kidney and pancreatic cancer.
Obesity could also cause cancer through other means, including:
- increasing the risk of esophageal cancer by causing ‘gastric acid reflux’, a condition where the stomach’s acids are briefly pushed back into the throat. This damages the lining of the esophagus.
- increasing the risk of gallstones, which in turn increase the risk of gallbladder cancer.
- being associated with physical inactivity or unhealthy diets.
Keeping a healthy weight reduces cancer risk and losing weight may reduce cancer risk
Studies have shown that overweight and obese people are more likely to develop cancer than people with a healthy body weight. It therefore makes sense that losing weight can help to reduce the risk of cancer, and scientists are now trying to confirm this with large studies.
One study found that women who lost 20 pounds or more had 11% lower risks of cancer overall compared to women who had never lost that much weight. Another study found that women who lost 10kg since menopause and kept the weight off more than halved their risk of breast cancer. Other studies have found similar results for breast and other types of cancer.
When people try lose weight through short-term fixes, in most cases, the end up putting the weight back on. It’s unclear how this ‘weight cycling’ affects the risk of cancer. But at least one study found that women whose weight had gone up and down by over 10 pounds, more than ten times, had higher risks of kidney cancer than those whose weight was stable. While this was just a single study, it does suggest that the best way to reduce the risk of cancer is to maintain a healthy body weight over time.
Studies have shown that overweight and obese people are more likely to develop cancer than people with a healthy body weight. It therefore makes sense that losing weight can help to reduce the risk of cancer, and scientists are now trying to confirm this with large studies.
One study found that women who lost 20 pounds or more had 11% lower risks of cancer overall compared to women who had never lost that much weight. Another study found that women who lost 10kg since menopause and kept the weight off more than halved their risk of breast cancer. Other studies have found similar results for breast and other types of cancer.
When people try lose weight through short-term fixes, in most cases, the end up putting the weight back on. It’s unclear how this ‘weight cycling’ affects the risk of cancer. But at least one study found that women whose weight had gone up and down by over 10 pounds, more than ten times, had higher risks of kidney cancer than those whose weight was stable. While this was just a single study, it does suggest that the best way to reduce the risk of cancer is to maintain a healthy body weight over time.
According to the American Cancer Society, obesity cost an estimated $75 billion in 2003 because of the long and expensive treatment for several of its complications. According to the National Institute of Health, $75-$125 billion is spent on indirect and direct costs due to obesity-related diseases.
The Solution to Obesity?
Follow a plant-based diet program such as the Death to Obesity Program. This program is a wellness program that is designed to help you lose weight (fat) the right way and permanently. The Death to Obesity Program is the only weight loss program that actually addresses how to eat comfort foods and your favorite foods instead of avoiding these foods and feeling deprived. Feeling deprived eventually leads most people to fall off the wagon and eventually regain the weight that they lost! Sound familiar?
With the Death to Obesity Program you will never fall off the wagon, because we include the very foods that would cause you to fall off the wagon in the first place! And, we show you how to transform these foods into healthier versions so that you will stick with the program.
Note: For more information about obesity and how to lose weight (and belly fat), refer to the Death to Obesity: The Weight Loss Solution ebook.
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