Does Obesity Cause Cancer?

Written by Dr. Steve Chaney on . Posted in Diets, Exercise, Healthy Lifestyle, Lose Weight, Obesity, Obesity and Cancer

Is The Obesity Epidemic Killing Us?

Author: Dr. Stephen Chaney

Does obesity cause cancer?

does obesity cause cancerYou probably already know that we are in the midst of a world-wide obesity epidemic. If not, here are some of the alarming statistics that characterize that epidemic:

  • The global prevalence of obesity has increased by 27.5% between 1980 and 2013.
  • 35% of the adult population worldwide is now overweight (BMI ≥ 25), including 12% who are classified as obese (BMI ≥30).
  • According to the NIH the situation is even worse in developed countries like the US where 75.1% of adults are now overweight, including 35.7% who are obese, and 6.3% who are very obese (BMI ≥40).

Unfortunately, overweight and obesity are not benign. You probably already knew that those excess pounds increase your risk of diabetes, heart disease, kidney failure and much more. You probably also knew that those excess pounds increase your risks of certain types of cancer such as colon, rectal, kidney, pancreatic, postmenopausal breast, ovarian and uterine cancer.

It’s been a little more difficult to determine just how much obesity increases cancer risk. However, a recent study suggests that the increased risk could be quite significant. In fact, if this study is correct, obesity may only be second to smoking as a preventable cause of cancer. The truth might just scare you skinny!

Does Obesity Cause Cancer?

cancer epidemicThe International Agency For Research On Cancer did a worldwide study, (Arnold et al, The Lancet Oncology 16: 36-45, 2015),  in which they looked at the effect of BMI on cancer incidence in adults aged 20 years or older. The BMI data was collected in 2002 and was segregated by sex and age groups. Recognizing that cancer takes decades to develop, they then collected data on newly diagnosed cancers in adults 30 and older in the same countries in 2012.  They were determined to get closer to answering the question, does obesity cause cancer?

By comparing BMIs in 2002 with the incidence of newly diagnosed cancers 10 years later they were able to calculate the effect of excess body weight (BMI ≥25) on cancer incidence. The results were startling:

  • They estimated that 481,000 new cases of cancer in 2012 in adults over 30 were attributable to excess weight.
  • That represents 3.6% of all new cancer cases, which makes overweight second only to smoking as a preventable cause of cancer.
  • Uterine cancer, postmenopausal breast cancer, and colon cancer accounted for 63.6% of all cancers caused by overweight. Other cancers affected by excess weight were rectal cancer, pancreatic cancer, kidney cancer, gallbladder cancer, and ovarian cancer.
  • The effect of excess weight on cancer risk was almost 3-fold greater for women (5.4% of new cancer cases) than for men (1.9% of new cancer cases).
  • In North America 111,000 new cases of cancer in 2012 for adults over 30 were attributable to excess weight. That represents 3.5% of all new cancers in men and 9.4% of all new cancers in women.
  • A quarter (about 118,000) of the worldwide cancer cases related to high BMI in 2012 could be attributed to the increase in BMI that has occurred since 1982.

The authors concluded “These findings emphasize the need for a global effort to abate the increasing numbers of people with high BMI. Assuming that the association between the high BMI and cancer is causal, the continuation of current patterns of population weight gain will lead to continuing increases in the future burden of cancer.”

What Does This Study Mean For You?

We have to stop kidding ourselves. That excess flab isn’t harmless. It is killing us, and cancer is a particularly gruesome way to go. It’s time to get serious about weight loss. Here are my top 5 tips for lasting weight loss.

  • fad dietsEat healthy low calorie meals and snacks with plenty of protein so that you maintain muscle mass while you are losing fat.
  • Avoid the fad diets. You don’t need to restrict carbohydrates or fats. You just need to focus on fresh fruits and vegetables, healthy proteins and modest amounts of healthy fats and healthy carbohydrates.
  • Find an exercise program you like and stick with it every day.
  • Focus on true lifestyle change rather than short term diets. A good strategy is to make one healthy change at a time rather than trying to do everything at once.
  • Change how you think about food, think about exercise, and think about your ability to make the kinds of changes that will lead to permanent weight loss. Don’t think of yourself as a fat person who is trying to lose weight. Think of yourself as a skinny person who happens to have a few extra pounds that are on their way out.

Of course, getting to a healthier weight isn’t the only change you want to make if you are trying to reduce your risk of cancer. Here are my top 7 lifestyle change suggestions (besides weight loss) for reducing cancer risk.

  • healthy eatingIf you smoke, stop. No ifs, ands, or buts. Smoking is still the #1 cause of cancer.
  • Eat a healthy diet (including supplements to fill the gaps).
  • Eat plenty of fresh fruits and vegetables, especially those that are good sources of cancer-fighting antioxidants, carotenoids, flavonoids, and polyphenols.
  • Eat fish and fish oil supplements to make sure that you get plenty of omega-3 fatty acids.
  • Minimize saturated fats and avoid trans fats. Substitute olive oil for vegetable oils whenever possible.
  • If you drink alcohol, drink it in moderation.
  • Avoid sun exposure as much as possible, and use sunscreen when outdoors.
  • Eat healthy proteins.
  • Minimize consumption of red meats and processed meats.
  • Use chicken, fish and vegetable proteins whenever possible.
  • Soy protein is particularly helpful for reducing the risk of breast cancer. (Yes, those scary blogs about soy and breast cancer are wrong. For accurate information, just go to https://healthtipsfromtheprofessor.com and type soy in the search box).
  • Get plenty of exercise.
  • Get regular check-ups.

So, does obesity cause cancer?  I think you now know the answer.

 

The Bottom Line

 

  • A recent study has shown:
  • 481,000 new cases of cancer worldwide each year are attributable to excess weight.
  • That represents 3.6% of all new cancer cases, which makes overweight second only to smoking as a preventable cause of cancer.
  • Uterine cancer, postmenopausal breast cancer, and colon cancer accounted for 63.6% of all cancers caused by overweight.
  • The effect of excess weight on cancer risk was almost 3-fold greater for women (5.4% of new cancer cases) than for men (1.9% of new cancer cases).
  • In North America 111,000 new cases of cancer for adults over 30 are attributable to excess weight. That represents 3.5% of all new cancers in men and 9.4% of all new cancers in women.
  • That excess flab isn’t harmless. It is killing us, and cancer is a particularly gruesome way to go. For my top 5 tips for lasting weight loss and my top 7 tips for reducing your risk of cancer, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Latest Article

Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

For more details on the study, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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