Timing Matters To Make Diet and Exercise Changes Last

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When it comes to making healthy lifestyle changes, which should come first — changing your diet or becoming more physically active?

Researchers from Stanford University School of Medicine report in the Annals of Behavioral Medicine that neither strategy was likely to help individuals meet healthy eating and fitness recommendations and stick with them for a year. For the best results, the scientists found that changing diet and fitness habits simultaneously made the most sense.

Previous studies suggested that providing people with too much information about nutrition and physical activity at once can be overwhelming, and tends to discourage, rather than motivate them to improve their habits. That, say the researchers, has led to the popularity of advising people to make incremental changes, and set smaller, more achievable goals to eat healthier meals and to become less sedentary. But, say some experts, continually making new changes can also drain energy and motivation, and lead to a drop in compliance over time.

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So to assess how the two strategies fared in a head-to-head comparison, the scientists recruited 200 inactive participants who were age 45 or older and randomly assigned them to one of four groups that provided nutrition and exercise coaching over the phone. One group was instructed about making diet and fitness changes at the same time, the second group were taught about diet changes first, then fitness changes four months later, the third group changed their exercise habits first and made changes in their eating habits four months later, and the final, control group were not instructed about either diet or fitness changes but about how to manage their stress.

The researchers tracked the groups for a full year to determine which strategy was more successful in helping participants achieve the nationally recommended goals of 150 minutes of exercise per week, eating five to nine servings of fruits and vegetables daily and keeping saturated fat intake at less than 10%.

Compared to the group that did not receive any dietary or exercise advice, the three intervention groups made healthy changes in their diet. Those that changed their fitness regimen first also significantly increased the amount of exercise they received daily compared to the other groups after four months. However, at the end of the year, the group that changed both diet and exercise at the same time was the only one that met the nationally recommended targets for both exercise and nutrition levels, while those who worked on improving their nutrition first were unable to meet the recommended levels of fitness after a year.

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The results raise interesting questions about behavior changes and compliance. The researches suspect that modifications to diet are easier to make than changes to physical activity, since meals are already part of a daily schedule, and exercise requires more effort to incorporate into an already busy day.

The findings show, however,  that pairing dietary and exercise changes may help to overcome some of the barriers people face in adding more physical activity into their lives. If folks change diet and exercise sequentially, the scientists say, they may end up placing more importance on the first set of behavior changes and feel less pressured to address the second set. Paying attention to both healthy behaviors at the beginning of a program, on the other hand, could help to give them equal priority, and therefore make it more likely that people will be able to maintain the habits over a longer period of time.