Obesity and Cancer – the link we don’t want to talk aboutApr 24, 2023
Did you know that having excess body fat increases your risk of cancer?
The topic of obesity and cancer risk is one that doesn’t garner as much attention as it should, given its significance in a world where cancer rates and obesity are on the rise. When it comes to the US alone, 31.8% of adults aged 18 years or older are obese or severely obese.
Shockingly, obesity and overweight is the second leading cause of cancer after tobacco smoking, causing over 600,000 cancer diagnoses per year in the US.
According to the International Agency for Research on Cancer (IARC), there is consistent evidence that having higher amounts of body fat is associated with an increased risk of 13 different types of cancer. These include postmenopausal breast, colorectal, esophageal, pancreatic, gallbladder, thyroid, endometrial, ovarian, gastric, liver, and kidney cancers, as well as multiple myeloma and meningioma. The cancers linked with overweight and obesity make up 40% of the cancers diagnosed in the US.
In fact, 55% of all the cancers diagnosed in women and 24% of the cancers diagnosed in men in the US are associated with overweight and obesity, and having excess body fat increases the risk of cancer-specific mortality by 17%.
So why is excess body fat a risk factor for cancer? The thing is, body fat doesn’t just sit there- it is metabolically active and secretes numerous growth factors, hormones, and inflammatory mediators.
Several mechanisms have been suggested as to why having excess fat increases cancer risk. These include:
- Overproduction of estrogen: Fat cells produce excess amounts of estrogen, which has been linked to increasing the risk of postmenopausal breast, ovarian, endometrial, and other cancers. Estrogen signals our cells to divide more often. Obese women have 130% higher estradiol levels than nonobese women.
- Hyperinsulinemia due to increased body mass: Individuals with obesity have higher insulin and insulin-like growth factor-1 (IGF-1) levels, which are both growth hormones that promote cell growth by encouraging cells to divide more often. Higher levels of insulin and IGF-1 have been linked to renal, colon, prostate, and endometrial cancers.
- Inflammation: A pro-inflammatory state is encouraged with higher levels of body fat in various ways. Fat cells produce pro-inflammatory hormones called adipokines, that either promote or hinder cell growth. The levels of an adipokine called leptin increase in the blood with higher amounts of body fat, and high levels of leptin can promote cell division. Next, excess fat tissue leads to a chronic state of inflammation in fat tissue due to fat cell growth and death, which leads to a localized toxic environment that can trigger cancer formation and progression. People with excess body weight also have higher levels of other inflammatory mediators, such as L-6, TNFα, and C-reactive protein.
In summary, hormones, growth factors, inflammation, immune system dysregulation and cause cells to divide more often, which increase the chance of cancer development.
The Importance of Maintaining a Healthy Weight through Lifestyle Changes
The importance of weight management for cancer prevention and following cancer treatment cannot be understated. Gaining more than 5% of your initial weight during or after cancer treatment, irrespective of baseline BMI, increases the risk of recurrence and reduces survival fivefold (that’s 400%).
The good news: If weight loss or maintenance is your goal, there are several simple lifestyle changes you can make TODAY to dramatically reduce your cancer risk and prevent a cancer recurrence. Plus, you’ll simultaneously reduce your risk of other chronic diseases as well, including diabetes and cardiovascular disease.
The Most Important Change You Can Make Today to Achieve Sustainable Weight Loss
What is the most important lifestyle change you can start making today to lose any excess weight and keep it off for good? - Adopt a plant-based diet.
The best available evidence in the medical literature shows that diets rich in whole plant foods and low in animal foods, ultra-processed foods, and alcohol are the most effective dietary patterns for sustainable weight loss.
A whole plant food diet is centred around the whole grains, legumes, vegetables, fruit, nuts, and seeds.
But how does a diet rich in whole plant foods support healthy weight loss? Through increased satisfaction with fewer calories. Whole plants foods are much less calorie-dense than ultra-processed and animal foods, while also being rich in water and fibre. The water and fibre in these foods fill our tummies and feed our healthy gut microbes, which allows us to feel full and leads to a production of specific compounds called short-chain fatty acids (SCFAs) that stimulate the production of appetite-suppressing hormones. These include GLP-1, PYY, and leptin. At the same time, fibre decreases the hormone ghrelin, which is an appetite-stimulating hormone. So, we end up feeling satiated while consuming less.
In addition to eating more plants and less animal and ultra-processed foods, make sure to move your body and manage stress.
Aim for 75 minutes of high intensity or 150 minutes of moderate intensity exercise every week. To help with stress management, try sitting in stillness for 20 minutes before you start your day, or following a guided meditation on YouTube or on an app like Calm or Insight Timer.
Whether you’ve just been diagnosed with cancer or you’ve already completed treatment, my holistic approach to wellness will help you make lasting lifestyle changes that support your body’s ability to heal — and improve your physical, mental, and emotional health for years to come. Contact me today to book a free consultation!
- Obesity, weight gain and cancer risk - WCRF International
- Obesity and Cancer: A Current Overview of Epidemiology, Pathogenesis, Outcomes, and Management - PMC (nih.gov)
- Obesity and Cancer Fact Sheet - NCI
- Vital Signs: Trends in Incidence of Cancers Associated with Overweight and Obesity — United States, 2005–2014 | MMWR (cdc.gov)
- Breasts: The Owner’s Manual - Dr. Kristi Funk
- The Proof is in the Plants- Simon Hill