The study's findings, published this week in the American Journal of Clinical Nutrition, have conflicting implications, says Michael Lowe, PhD, a professor at Drexel's College of Arts and Sciences.
"On one hand, giving overweight people a realistic sense of the dilemma that they are in and the powerful forces they are up against -- including a genetic predisposition toward obesity and an increased susceptibility to many food cues in the environment -- may actually promote cognitive restraint over their eating in the short-term," Lowe said. "But, on the other hand, this message did not motivate participants to make numerous changes to the foods they surround themselves with."
Lowe and a team of researchers originally set out to determine the effectiveness of three weight loss interventions: behavior therapy, behavior therapy plus meal replacements, or a condition focused on getting people to change foods in their home food environments. They enrolled 262 overweight and obese individuals and assigned them to one of the three methods, while tracking their weight over a three-year period.
Behavior therapy -- the current "gold standard" in weight loss treatment -- involves group support, regular weigh-ins, exercise, explicit goal setting and monitoring food intake, while meal replacement treatment replaces breakfast and lunch with calorie-controlled shakes or nutrition bars.
Behavior therapy is aimed at bolstering someone's internal sense of self-regulation over food intake and exercise. But research has shown that increases in self-control are not sustainable, and lost weight is almost always regained. The powerful lure of foods high in fat, sugar and salt has been well-documented, and existing treatments do not do enough to ensure that foods kept in the home are permanently changed in ways that make self-control more feasible, according to Lowe.
"You can't just give advice," he said. "You have to work with people to eliminate and substitute very specific foods, and teach them to prepare food differently."
That's why his research team hypothesized that modifying the home food environment (or HFE) would be the most effective strategy for losing and maintaining weight loss. Participants in this group were given homework assignments to identify and make numerous changes to specific foods that were still satisfying but less calorically damaging.
"Asking people to make healthy decisions, when there are thousands of food choices available, is both emotionally challenging and also complicated," Lowe said. "HFE treatment is really about mechanically trying to ensure that these changes are made, so the level of chronic temptation generated by foods in their homes is reduced."
Most importantly, the research team repeatedly reminded the HFE group about the challenges associated with weight loss and maintenance. In doing this, the researchers aimed to acknowledge the participants' vulnerability to overconsume favorite foods.
"We said, 'It's impressive and encouraging that you are taking this step to improve your weight and health, but we need to help you understand the daunting challenges you're facing.' The reason we did this was not to discourage them, but to give them a more realistic sense of how crucial it is for them to make lasting changes in their parts of the food environment that they could control," Lowe said.
People struggling with their weight are likely to hold themselves responsible, even though a number of internal (heredity, for example) and external (fast food restaurants) forces are at play and beyond their control, Lowe said. The researchers suggested that by making multiple changes to their food environment, participants would be reducing the need to perpetually exercise self-control to maintain the weight they lost.
In addition to measuring the participants' weights during six assessment sessions over three years, the researchers also assessed conditions such as binge eating, quality of life, cognitive restraint and food cravings by using questionnaires and statistical analysis.
At the end of the three-year study period, the researchers found that those in the HFE group lost more weight than those in the behavior therapy group. However, the differential in weight loss was modest, and all participants showed the familiar trend toward weight regain.
"We failed to get them to translate our warnings into the kind of actions we were trying to get them to take," Lowe said.
The warnings did, however, have a positive -- though unanticipated -- effect. Cognitive restraint -- defined by a participant's ability to actively make healthy choices and measured with mediation analysis -- showed the longest, most prolonged increase in the HFE participants, when compared to the other two treatment groups.
This suggests that the researchers' rhetoric about the difficulties of sustaining weight loss may have actually caused the participants in the HFE group to "push back" against this message and increase their vigilance over their eating, Lowe said.
"That is, by questioning the usefulness of building self-control skills, the HFE treatment may have bolstered the very capacity it was meant to downplay -- stronger self-control with regard to food," the study authors write.
Though surprising, these results have potentially clinically-useful implications. By emphasizing the many factors that make lasting weight loss so difficult, it may help motivate individuals to mentally and behaviorally cope with these factors, according to Lowe.
"Rather than acting as cheerleaders giving facile encouragement, leaders of weight loss groups might serve their clients better by providing a more sobering description of the challenges participants face," Lowe explained.
However, since the participants in the HFE condition did not make greater changes to their home food environment, future studies should examine how to better improve and monitor this weight loss intervention, such as sending dieticians or other practitioners directly to clients' homes for periodic visits.
For Lowe, the study reinforces the challenging reality for those seeking to maintain weight loss -- and makes a strong case for policies (such as Philadelphia's beverage tax) that focus on preventing, rather than treating, the problem of obesity in the United States.
"Once these conditions develop and you are continuing to live in the same obesogenic environment, it is unrealistic to expect that many people will be able to sustain a large weight loss," he said. "Society ultimately needs to prevent these unhealthy weight gains before they occur."