Change diet, exercise habits at same time for best results, study says

Now, researchers at the Stanford University School of Medicine have discovered that focusing on changing exercise and diet at the same time gives a bigger boost than tackling them sequentially. They also found that focusing on changing diet first -- an approach that many weight-loss programs advocate -- may actually interfere with establishing a consistent exercise routine.

Their findings were published online April 21in the Annals of Behavioral Medicine.

"It may be particularly useful to start both at the same time," said Abby King, PhD, lead author of the study and a professor of health research and policy and of medicine. "If you need to start with one, consider starting with physical activity first."

The few published studies on how to introduce more than one shift in healthy habits report conflicting findings -- and few have looked at exercise and dietary change together. In examining the issue, the researchers also wanted to study people who specifically complained that the demands of their schedules didn't give them enough time to make healthy dietary and exercise choices. The reasoning was that if successful programs could be developed for these time-strapped individuals, they would likely work for others, as well.

Researchers split 200 initially inactive participants, ages 45 and older and with suboptimal diets, into four different groups. Each group received a different kind of telephone coaching. The first group learned to make changes to diet and exercise at the same time. The second group learned to make dietary changes first and didn't try changing their exercise habits until a few months later. The third group reversed that order and learned to change exercise habits before adding healthy dietary advice. The fourth group, for comparison, did not make any dietary or exercise changes, but was taught stress-management techniques. Researchers tracked participants' progress in all four groups for a year.

Despite the challenge of making multiple changes to their already-busy routines at once, those who began changing diet and exercise habits at the same time were most likely to meet national guidelines for exercise -- 150 minutes per week -- and nutrition: five to nine servings of fruit and vegetables daily, and keeping calories from saturated fats at 10 percent or less of their total intake.

Those who started with exercise first did a good job of meeting both the exercise and diet goals, though not quite as good as those who focused on diet and exercise simultaneously.

The participants who started with diet first did a good job meeting the dietary goals but didn't meet their exercise goals. King, who also is a senior researcher at the Stanford Prevention Research Center, speculates this is because changing diet and introducing exercise both have unique challenges. "With dietary habits, you have no choice; you have to eat," she said. "You don't have to find extra time to eat because it's already in your schedule. So the focus is more on substituting the right kinds of food to eat."

But, she said, finding time for exercise if you already have a busy schedule can be challenging. She pointed out that even the most successful group, those receiving the two behavioral health programs simultaneously, lagged behind in meeting the physical activity goal at first, though over the course of a year were eventually able to meet it.

King credits the way health educators explained the dietary and exercise advice to participants for their overall success and the study's high retention rate. They met with participants in person just once at the beginning of the one-year period. After that, they called once a month, spending as little as 10 to 15 minutes -- and no more than 40 minutes -- providing advice and support for diet and exercise.

For the participants, whose schedules and stressful lives had previously interfered with making healthy lifestyle choices, this approach worked, King said. She said that telephoning participants was a convenient and flexible way to provide personalized information. "These health behaviors aren't things that we change over a six-week period and then our job is done," she said. "They're things that people grapple with their whole lives, so to develop 'touches' of advice and support in a cost-efficient way is becoming more and more important."

Participants in this study were not actively trying to lose weight, just trying to develop healthy habits. King's next step is to test the same sequential-versus-simultaneous approaches among people who are trying to lose weight.

Other Stanford authors of the study include senior research scholar Cynthia Castro, PhD; statistical analyst David Ahn, PhD; and former postdoctoral scholars Matthew Buman, PhD, and Eric Hekler, PhD, (who are both now at Arizona State University) and Guido Urizar, PhD (now at Cal State Long Beach).

The study was supported by the National Institute on Aging (grant R01AG21010) and the National Heart, Lung and Blood Institute (grant 5T32HL007034).