Weight Loss Blog

Weight management, exercise and proper nutrition are key to reducing your risk of cancer. And the earlier in life you adopt these practices, the better off you’ll be, a new study suggests.

Factors such as birth weight, childbearing, breast-feeding, and adult height and weight also influence cancer risk, according to the report released Wednesday by the American Institute for Cancer Research and the Britain-based World Cancer Research Fund. Understanding how these factors affect cancer risk, and how to put this information to use to prevent the disease, offer promising new directions for cancer research, the study authors said.

“We need to think about cancer as the product of many long-term influences, not as something that ‘just happens,’ ” Dr. Walter J. Willett said in a prepared statement. Willett, a professor of epidemiology and nutrition at the Harvard School of Public Health, was one of 21 authors of the report, Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective.

“Examining the causes of cancer this way, across the entire lifetime, is called the life course approach,” he added.

The report, an analysis by scientists from around the world of more than 7,000 studies, offers 10 recommendations to help prevent cancer. They include staying lean, getting at least 30 minutes of exercise daily, limiting your intake of red meat and alcohol, and avoiding processed meats.

“These findings are right on,” said Colleen Doyle, director of nutrition and physical activity at the American Cancer Society. “They are consistent with our own nutrition and physical activity guidelines. They clearly put the emphasis where the emphasis needs to be, and that’s on controlling your weight.”

“This is a good-news report,” added Karen Collins, a nutrition adviser at the American Institute for Cancer Research. “If we are watching our weight, working regular physical activity into our daily life and eating a healthy balance of foods, we could prevent a third of cancers,” she said. “Extra weight is not dead weight,” she said. “It’s an active metabolic tissue that produces substances that promote the development of cancer.”

“People should take this message to be empowering,” Collins said.

The analysis of the studies found a definite link between excess fat and cancers of the esophagus, pancreas, colon and rectum, endometrium, kidney as well as breast cancer in postmenopausal women.

The risk from excess weight begins at birth, according to the report. The reason for the link between birth weight and breast cancer has to do with body fat. Excess body fat influences the body’s hormones, and these changes can make it more likely for cells to undergo the kind of abnormal growth that leads to cancer, the researchers said.

In addition, overweight girls can start menstruating at an earlier age. So, over their lifetime, they will have more menstrual cycles. This extended exposure to estrogen is associated with increased risk for premenopausal breast cancer, the report found.

Not smoking is the most important thing one can do to reduce the risk of cancer, Doyle said. But, she added, “there are estimates that obesity will overtake smoking as the leading preventable cause of death.

“It’s great to see another report that emphasizes being active, watching your weight and eating a healthy diet are not only going to help you reduce your risk of cancer but heart disease and diabetes as well,” Doyle said.

The report also found that breast-feeding can lower a mother’s risk for developing breast cancer. In addition, breast-fed infants have a lower risk of becoming overweight or obese, and this means a lower risk of developing cancer.

“The evidence is uniformly strong on breast-feeding, and the fact that it offers cancer protection to both mothers and their children is why we made breast-feeding one of our 10 Recommendations to Prevent Cancer,” Willett said.

In addition, tall people seem to have a higher risk of colorectal and postmenopausal breast cancer, according to the report.

“We found that tallness is also probably linked to increased risk for ovarian, pancreatic and premenopausal cancer as well,” Willett said. Although the association between height and cancer is convincing, tall people are not destined to get cancer, he added.

Willett noted that being at increased risk is not a guarantee that you are going to develop cancer. “Risk isn’t fate,” he said. “The evidence clearly shows that risk can be changed.

“We wanted to point these emerging links out, because we now believe them to be more important than the scientific community, much less the public, has yet realized,” Willett added. “Whether or not we get cancer has to do with our genes and with the choices we make everyday. Our cancer risk is also influenced by our whole accumulated life experience, from conception onwards.”

Body weight and composition is a big factor, one expert said.

“This report really reinforces the connection between being overweight or obese and the increased risk of many, if not all, cancers,” said Carolyn Lammersfeld, the national director of nutrition at Cancer Treatment Centers of America. “The majority of Americans are not aware of that connection. They are more concerned with pesticides and environmental contaminants, but obesity is a much greater risk factor,” she said.

But risks can be minimized, she added. “If you don’t have cancer, it’s never too late to try to do what you can to lower your risk,” Lammersfeld said. “In addition, cancer survivors should follow the diet and weight recommendations to prevent a return of cancer.”

The report said that people should not use dietary supplements to try to offset cancer risk — something Lammersfeld agreed with. “You can’t fix a crappy diet with supplements,” she said.

Report stresses link between obesity and cancer

Keeping slim is one of the best ways of preventing cancer, as is avoiding excessive amounts of red meat and wine, a landmark study has revealed.

The World Cancer Research Fund (WCRF) said the link between body fat and cancer is closer than generally realized.

It found convincing evidence of a link to six types of cancer, five more than in its last report, 10 years ago.

Among the new types are colorectal (bowel) and post-menopausal breast cancer.

Professor Michael Marmot, chair of the panel of 21 eminent scientists who compiled the report, said: “We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood.”

The report, which selected 7,000 studies from a worldwide pool of 500,000 written since records began in the 1960s, includes five key findings.

They are that processed meats, such as ham and bacon, increase the risk of colorectal cancer, and should be eaten sparingly.

Another is the link between red meat and colorectal cancer, for which the evidence is stronger than ever. People should not eat more than 500g of cooked red meat a week — or between 700g and 750g for “blue” or uncooked meat.

A further finding was the strongest evidence yet that alcohol is a cause of cancer. If people must drink, the report said, they should limit their intake to two units a day for a man or one for a woman. A unit is a half pint of beer or a small glass of wine.

The report recommended mothers breastfeed exclusively for the first six months after birth followed by complementary breastfeeding, after evidence showed breastfeeding protects the mother against breast cancer.

It did not recommend dietary supplements as prevention.

“This report is a real milestone in the fight against cancer, because its recommendations represent the most definitive advice on preventing cancer that has ever been available anywhere in the world,” said Professor Martin Wiseman, project director of the report.

Scientists believe there are several reasons for the link between body fat and cancer.

One is the relationship between excess fat and the hormonal balance in the body.

Research has shown that fat cells release hormones such as estrogen, which increases the risk of breast cancer, while fat around the waist encourages the body to produce growth hormones, which can increase levels of risk.

Evidence of a link is most convincing for cancer of the esophagus, pancreas, colorectum, endometrium (womb), kidney and post-menopausal breast cancer.

The report makes 10 recommendations including 30 minutes of moderate activity a day, rising to 60 minutes; drinking water rather than sugary drinks; eating fruit, vegetables and fiber and limiting salt consumption.

Obese people face bigger cancer risk

Obese people have a higher risk of certain kinds of cancer, according to a report Wednesday which found that red meat and processed meats cause bowel cancer.

The World Cancer Research Fund (WCRF) report, based on analysis of some 7,000 cancer studies from around the world, said there was “convincing” evidence that excess fat can cause breast, bowel and pancreatic cancer.

“We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood,” said Professor Michael Marmot, who chaired the panel which drew up the report.

“This might sound difficult but this is what the science is telling us more clearly than ever before. The fact is that putting on weight can increase your cancer risk, even if you are still within the healthy range.

The 360-page report, available on the website www.dietandcancerreport.org and launched in London, lists specific cancer risks for a range of foodstuffs.

For vegetables and fruit there were no “convincing” evidence of a link to particular cancers, it said, but for meat and fish there were clear indications of increased risks.

“The strongest evidence, corresponding to judgements of convincing’ and probable’, shows that red meat and processed meat are causes of colorectal cancer,” said the report.

The findings will fuel particular concern amid signs of increasing obesity levels in the Western world.

According to recent government-backed forecasts, 60 percent of men, 50 percent of women and a quarter of children in Britain will be obese by the year 2050. In 2004 nearly a quarter of men and women in England were obese.

The report, including recommendations by a panel of 21 experts, found a strong link between fat around the abdomen and bowel cancer, and a “probable” connection between body fat and gall bladder cancer.

“So the best advice for cancer prevention is to avoid weight gain, and if you are already overweight then you should aim to lose weight,” said Marmot.

Clinical obesity is defined as a Body Mass Index (BMI) of 30 or more, where BMI is calculated by dividing a person’s weight in kilograms by height in metres squared.

Normal weight corresponds to a BMI of 18.5-24.9, while 25-29.9 is “overweight”.