Diet tops exercise for cutting weight, cancer risk, new study shows – Fred Hutch News Service

The scales of the women studied revealed the power of portion over perspiration:

• Women who followed the weight-loss diet – a daily calorie goal based on starting weight and a reduction of fat to less than 30 percent of total calories – lost, on average, 8.5 percent of their starting weight after one year.
• Those who followed that diet while exercising moderately to vigorously for 45 minutes a day, five days a week lost, on average, a bit more – 10.8 percent of their weight after a year.
• But those who stuck to that exercise plan while not curtailing their calories lost, on average, only 2.4 percent of their weight when the year had elapsed. (Most women will not gain a substantial amount of muscle mass with exercise, said McTiernan.)

The study enrolled 439 women from the Seattle area who were randomly placed into one of four groups – exercise only, diet only, exercise plus diet, or no change to health habits. The women were aged 50 to 75, sedentary, postmenopausal, and either overweight or obese but otherwise healthy.

“We know that being overweight and having a sedentary lifestyle is associated with an increase in risk for developing certain kinds of cancer. However, we don’t know exactly why,” Duggan said.

That’s where the three proteins examined by Duggan and McTiernan may offer clues.

Blood samples were collected from the study participants at the trial’s start. In each of those samples, researchers measured three proteins – VEGF, PAI-1 and PEDF – that flow through the body and help in the formation of brand-new blood vessels, a process called angiogenesis.

That mechanism can boost the body in tiny or most important ways, such as amid wound healing. But angiogenesis – a sprouting of fresh blood vessels to carry oxygen and nutrients – also occurs during the growth of tumors. The three measured proteins are involved in nurturing the growth and survival of cancer cells.

Judy Casey, 72, was a trial participant who was part of the exercise-only group. She was motivated to enroll, she said, because her mother, Marion, was diagnosed with breast cancer and died of thyroid cancer in 1999 at age 79.   

“I’ve never been a large person but I found that I walked taller (from exercising), that it improved my physical and emotional health,” said Casey, who lost between 5 and 8 pounds during the study.  

The women who adhered for one year to the caloric restriction and lower-fat eating – or a combination of the diet and workout plans – had significantly decreased levels of those angiogenesis-related proteins, the study found.

Those same women met regularly with dietitians who helped them infuse their menus and dining habits with more fruits and vegetables, better portion control, daily weighing and food journaling.

Lower levels of the cancer-associated proteins were not found in the women who participated in the exercise-only group, the study showed.

The Hutch researchers cannot currently say that when someone loses weight and lowers their levels of angiogenic-related proteins it definitively decreases that person’s likelihood of a cancer diagnosis.

But the findings do add to a growing body of evidence showing the link between being overweight and having elevated levels of certain proteins associated with a higher cancer risk, Duggan said.

The National Cancer Institute and the Breast Cancer Research Foundation funded the study.

The authors say they would certainly advise sedentary, overweight, older adults to perhaps use the findings as a motivation to improve their diets and add more cardio.

“It’s never too late to adopt a health lifestyle that can lower risk factors for cancer,” McTiernan said.

Adults who have actually a stable, healthy body mass index (less than 25) don’t need to restrict calories, McTiernan added.

“Regardless of whether weight loss is a goal, exercise at any level is beneficial for numerous health effects,” Duggan said. “However, diet is the most effective method to achieve weight loss.”

Participant Judy Casey said that since the study ended she has actually worked to maintain her routine of brisk, three-mile walks in her Seattle neighborhood, she said.

“The findings are interesting. I’m always telling myself: you cannot eat cookies for breakfast. And the exercise, well, I don’t think it ever becomes easy. The people who say, ‘If I don’t run I get crazy,’ I would certainly like to be able to say that about my walking,” Casey said. “Walking is still my thing. But I would certainly always like to say I had a lot of fruits and vegetable today.”