By Susan M. Kleiner, PhD, RD, FACN, CNS
Are you fat? Or are you in a slump and beginning to get a little pudgy around the edges? If you are, here’s another good reason to lose weight. A new study sponsored by the American Cancer Society published in the New England Journal of Medicine in April showed dramatically increased risks of dying from all types of cancers in people who were obese within the past 16 years of their lives. Doctors are hoping this piece of news will finally motivate the predominantly overweight American population to lose weight and keep it off.
The statistics from the new study are staggering; women who are obese are at the greatest risk of dying from cancer. We’ve known for years that overweight and obesity are strong risk factors for hyperinsulinemia, insulin-resistance, type 2 diabetes mellitus, hypertension, high cholesterol and heart disease. Scientists have also known that excess body weight in women increases the risk of cancers of the endometrium, kidney, gallbladder and breast (in postmenopausal women). But this study shows that compared to normal weight women with a body mass index (BMI— a measure of the proportion of weight to height used to determine obesity) ranging from 18.5 to 29.9, women with a BMI of 30 to 39.9 had a 10 percent increased risk of dying of certain cancers. Obese women with a BMI of 40 or greater had a 62 percent increased risk of dying from all cancers. The list specifically included breast, cervical, colorectal, esophagus, liver, gallbladder, uterine, kidney, non-Hodgkin’s lymphoma, multiple myeloma, ovarian and pancreatic cancers.
A DESIGN IN QUESTION
The design and interpretation of the study are under some question. Subjects in the study were asked their height and weight on a questionnaire administered one time at the outset of the study. Illness and causes of death were then followed for the next 16 years. The average age of the study participants was 57. Some experts argue that self-reports of body weight and height are suspect and are often under-reported, giving spurious statistical results. Secondly, basing a research study on BMI reported only once does not give us a real picture of what might have happened to body weight over those 16 years. Lastly, as addressed by the researchers themselves, obese patients are often under-diagnosed and under-treated for disease. This is especially true for obese women with cancers of both the breast and ovaries. In this case, even if obesity was a risk factor in the development of the cancer, poor medical care may have been the reason for the ultimate death.
On the other hand, if these BMI levels were below the actual values, and the risk of dying of cancer increased with increasing BMI values, then it is possible that the risk of dying from cancer if you are obese may be even higher than reported. While there’s no question that multiple reports of BMI would have been more representative of the body weight condition of the subjects over time, research following body weight patterns of adult Americans has shown that body weight generally increases, rather than decreases, decade by decade. It is unlikely that a majority of subjects became significantly leaner over the 16 years of the study. The study seems to show that there is a very high risk of dying of cancer if you are obese even at one time during your adult years.
The study re-enforces that the more overweight you are, the greater your risk of dying from cancer, regardless of the underlying factors. It is a call to action for a population that appears to be incapable of finding solutions to the public health crisis before us.
This research does not tell us why being overweight causes cancer, or whether the risk of dying from cancer decreases if you lose weight. But what we do know from other studies is that increased adipose (fat) tissue disturbs hormone control and the chemistry of cells. If you are obese, you have a two-fold increased risk of dying of cancer. If you carry your extra weight around your abdomen and your body resembles the shape of an apple rather than a pear, where body fat is stored in the hips and thighs, then you have a greater risk of dying from all chronic lifestyle diseases, including cancer. Compared to smoking, which is the number one cause of cancer, obesity is the second greatest risk factor for developing cancer and dying from it.
THERE IS SOME GOOD NEWS
Among all of this bad news are the studies looking at energy intake and its links to metabolic syndrome and cancer. The multi-decade study investigating calorie-restriction and reduced illness and death in rhesus monkeys has been ongoing for over 15 years. The monkeys have been fed a slightly calorie-reduced (CR) diet compared to their peers who could eat at will. The CR monkeys maintain a healthy body fat range between 10-22 percent and don’t get fat, they avoid the age-related changes that lead to abnormal blood sugar control, obesity and diabetes, and they may live longer.
Numerous laboratory studies are beginning to link high-energy intakes with pre-cancerous changes in the machinery of cells and the chemistry of the body. When energy getting to the cells is restricted slightly, the risk of pre-cancerous changes diminishes.
GET IN ON THE ACTION!
If you’re already fit, then make sure you eat well and stay physically active. If you are overweight, even though we don’t have conclusive evidence that shows if you lose weight you’ll decrease your risk of developing cancer, you know that your risk is high right now. Undoubtedly, you’ll be healthier if you eat a more balanced diet and include physical activity in your schedule every day. If you control your calorie intake, you’ll ultimately lose weight.
Establish an action plan. Most people find success with a planned nutrition and exercise program, rather than just flying by the seat of their pants. A new study that reviewed six research publications evaluating diets between 800 and 1,600 calories using vitamin and mineral-fortified meal replacement products (MRPs), plus at least one meal per day, showed that subjects successfully lost weight during a three-month period and then again at a one-year follow-up. They also showed positive changes in biomarkers of cardiovascular disease and diabetes. The subjects using the MRPs showed significantly better weight loss results compared with those not using the products, but following a diet with the same number of calories.
Not only are calories and body weight important, but so are the foods you eat— and don’t eat. Some studies point toward the Mediterranean Food Guide Pyramid as one of the best anti-cancer diet strategies.
There are numerous diet plans available. What works for your neighbor might not work for you. But what is most important is that you find a plan that will work with your lifestyle for the rest of your life. Don’t look for a quick fix. Before you know it, you’ll have dropped off the plan and found all the weight that you lost, and more. Make sure to include daily exercise that pumps your muscles and your heart, get plenty of rest and find a creative outlet to turn to when your spirits are low. You will be stronger, happier and better equipped to handle the stresses of the day. This is where you have control over cancer.