A prospective study followed 291,778 individuals, ages 43-58, who did not have diabetes, heart disease or cancer at the beginning of the study. After 11 years, significantly higher cancer and heart attack rates were found in subjects who had any one of these five lifestyle factors: being overweight, smoking, drinking alcohol, not exercising, or not following a high-plant (Mediterranean-style) diet (BMC Medicine, Jan 15, 2020;18(5)). Having more than one of the factors increased heart attack and cancer risk even more. In North America, more than 40 percent of cancers and cancer deaths from 26 different cancers are associated with lifestyle factors such as excess weight, a faulty diet or lack of exercise (Cancer Research Update, Nov 21, 2017).

Cancer prevention is associated with:
• Avoiding obesity, which lowers insulin and insulin-like growth factor-I (Frontiers in Physiology, 2012;3(318):1–10) and inflammation (Cancer Research, 2012;72(9):2314–2326).
• Exercising regularly (Nature Reviews Cancer, 2008;8(3):205–211).
• Eating lots of vegetables, fruits and other anti-inflammatory foods (British Medical Journal, 2006;333(7578):1109–1111; BMJ, Nov 10, 2011;343).
Many other studies have found the same associations between these lifestyle factors and prevention of heart attacks and cancers (Eur J Intern Med, 2015;26(3):211–6; Lancet Public Heal, 2017;2(6):e277–85; Ann Fam Med, 2018;16(4):322–9; PLoS One, 2014;9(7):e103120; Public Health Nutr, 2002;5(6b):1113–24; PLoS Med, 2018;15(3):1–18).

Why Exercise Helps to Prevent and Treat Cancer
Lack of moving about, not just lack of exercise, causes a tremendous loss of muscle size and strength. A review of close to 150 studies found that people who have small muscles are at increased risk for developing multiple cancers, and that after they develop a cancer, they also have more hospitalizations, longer hospital stays and lower survival rates (Journal of Cachexia, Sarcopenia and Muscle, Jan 8, 2020). More than 20 years ago, several studies showed that some “overweight” people with chronic diseases lived longer than those who were very skinny. The explanation has nothing to do with fat protecting people from dying. The people who weighed more had more muscle and it was the extra muscle, not the fat, that helped to protect them from dying from cancer (Annals of Oncology, Mar 1, 2018;29(suppl_2):1–9; Annals of Palliative Medicine, Jan, 2019;Vol 8(1)). If a hospitalized cancer patient lies in bed, not moving very much, the lack of movement can cause a loss of up to 17 percent of muscle mass in just 10 days (JAMA, 2013;310(15):1591–1600), and with loss of muscle comes loss of the immune system’s ability to fight off cancer. Muscle loss is a major killer of people who suffer from cancer (Lancet Oncol, 2008 Jul;9(7):629-35), and increased rate of muscle loss is associated with cancer progression (J Clin Oncol, 2013;31:1539– 1547).

Larger muscles reduce inflammation, and inflammation increases cancer risk. A high rise in blood sugar causes inflammation by causing sugar to stick to cells and damage them. This cell damage turns on your immune system to try to cause healing. If your immune system stays on all the time, it attacks you just like it attacks invading germs. Having large muscles helps to protect you from high rises in blood sugar, so larger muscles reduce inflammation by removing increased amounts of sugar from the bloodstream (Mayo Clinic Proceedings, April 2019;94(4):643–651). Liffting weights for 12 months can increase muscle weight by more than two pounds in breast cancer survivors (Obesity, 2017;25:346– 351).

Healthful Nutrition Helps to Treat Loss of Muscle in Cancer Patients and Survivors
In addition to lack of exercise and obesity, poor nutritional status in cancer causes a tremendous loss of muscle size and strength (Radiother Oncol, 2003; 67: 213– 220), and proper nutrition can help to treat patients with cancer (Evidence-Based Comp and Alt Med, Oct 30, 2013;2013:917647). The nutritional needs for a cancer patient to retain muscle mass adequate to help control cancer (Journal of Cachexia, Sarcopenia and Muscle, Jan 8, 2020) include:
• energy (25–30 kcal/kg/day)
• protein (1.0–1.5 g/kg/day)
• branched chain amino acids (leucine: 2–4 g/day)
• glutamine (0.3 g/kg/day)
• carnitine (4–6 g/day)
• creatine (5 g/day)
• fish oil/eicosapentanoic acid (2.0–2.2 g/day EPA and 1.5 g/day DHA)
• vitamins/minerals (e.g. vitamin D: 600–800 international units per day)

A Mediterranean-style diet is associated with reduced risk for certain cancers (Annals of Internal Medicine, July 19, 2016) because it reduces inflammation that is associated with increased risk for cancer (Nutrients, Aug 2019;11(8):1842; Endocr Metab Immune Disord Drug Targets, Dec, 2016;14(4):245–254). The diet included:
• unlimited plant-based foods such as beans, vegetables, fruits, nuts, seeds and whole grains
• seafood twice a week
• plain coffee, tea and water
Red meat was limited to less often than once a week.

Obesity Increases Cancer Risk
A Spanish study of 54,446 people showed that obese women are 12 times more likely to develop cancer and five times more likely to suffer a heart attack than women of normal weight, and obese men are twice as likely to develop cancer than those of normal weight (Prev Med, Jan 17, 2018). The study also showed that only 26 percent of that population had normal weight. Overweight women who lost 12 pounds in their 40s, and did not put it back on, reduced their risk of suffering cancer by 20 percent.

A study from Stanford showed that as people gained six pounds in one month, their bodies suffered unhealthy changes in genes in their cells, types of colon bacteria, inflammation, and heart-attack risk factors. After they lost the added weight, these functions returned to normal (Cell, Jan 2018).

My Recommendations
You can reduce your risk for many cancers, as well as heart attacks and diabetes, by avoiding excess weight, exercising regularly and eating a plant-based diet. See:
Heart Disease and Cancers Share Many Risk Factors
Breast Cancer Survival Improves with Healthful Lifestyles
Exercisers Have Fewer Heart Attacks
Most Type II Diabetics Could Be Cured with Lifestyle Changes