Behavioral weight-loss interventions that focus on diet and/or exercise are considered the most effective treatments for obesity. Such programs have also been proven effective in treating and reducing the risk of developing type 2 diabetes. Weight loss through diet and exercise modification has been found to have a preventive effect by reducing the risk of developing diabetes by more than 30% with as little as a 4.5 kg weight loss.⁴ In addition, several studies have found that individuals with diabetes derive many health benefits from losing weight.

Although weight loss has been found to be beneficial in treating and preventing diabetes, the long-term efficacy of weight-loss on diabetes is unknown given that weight regain is common.⁵ This articles will describe the structure and components of a typical behavioral weight-loss program and then discuss some new research directions aimed at improving treatment outcomes.

Problem solving and assertiveness techniques are taught so that participants can effectively deal with difficult situations that threaten their weight control efforts. Thoughts and emotions related to overeating and inactivity are also addressed during treatment sessions to understand and decrease the influence of these factors on weight control. Toward the end of treatment, attention is given to motivation enhancement and relapse prevention to help individuals maintain their weight loss. Table 2 lists sessions covered in a typical behavioral weight-loss program.

Few studies have addressed whether modest weight-loss goals are feasible or effective in improving long-term weight loss. One challenge with this shift in goal setting appears to be the acceptability of modest goals among individuals interested in losing weight. Foster and colleagues¹⁰ found that women participating in a weight- loss program expected to lose 34% of their body weight. However, after 48 weeks of treatment they lost only 16% of their initial weight, and most indicated that they were not satisfied with their weight loss. These and other researchers have speculated that unrealistic expectations and dissatisfaction with weight loss may be a primary factor in weight regain. Thus, convincing patients that modest weight-loss goals of 5–15% are attainable and sufficient for health improvements may prove to be a challenge.

A recent study conducted by Jeffery et al.¹¹ examined whether reaching a self-selected weight-loss goal was related to better long-term weight loss. They found that participants in a behavioral weight-loss program who reached their weight-loss goal did not maintain a greater weight loss at follow-up. Moreover, they found that participants who lost the most during the initial 6 months had the best long-term outcome. Thus, these correlational data do not support the hypothesis that encouraging modest initial weight-loss goals improves long-term weight loss.

Another approach to modifying unrealistic weight-loss goals has been to promote self-acceptance of weight using a "non-dieting" treatment. These programs aim to combat the belief that "thinner is better" and encourage participants to abandon efforts to restrict intake and instead eat only in response to physiological signals of hunger. Although these programs have produced positive changes in mood and psychological functioning, they unfortunately produce little or no weight loss,¹² leaving individuals vulnerable to the negative consequences of obesity. Whether modifying weight-loss goals will improve long-term weight loss deserves further attention.

Two of the most frequently cited barriers to developing consistent exercise habits are lack of time and limited access to exercise equipment or a place to exercise. Recently, Jakicic and colleagues¹⁴ designed a study to examine the effect of addressing these common barriers. To reduce the problems associated with lack of time, these researchers suggested that exercise be completed in four 10-minute bouts rather than as one continuous 40-minute bout. To improve access, treadmills were provided to some of the participants. These strategies were tested within the context of a weight- loss treatment program. All subjects were encouraged to exercise a total of 40 minutes for at least 5 days per week. There were three groups in this study: 1) long bout, a group that was encouraged to exercise in one long bout (40 minutes) 5 days per week, 2) short bout, a group that was encouraged to break up their activity into several 10 minute bouts that add up to 40 minutes per day for at least 5 days per week, and 3) short bout with treadmill, a group that was encouraged to engage in several short bouts of exercise and that also received a treadmill to use in their home.

After 18 months of behavioral weight-loss treatment, the short bout with treadmill group lost more weight than the short bout group and exercised at a higher level than both the long-bout and short-bout groups. All subjects experienced an increase in cardiorespiratory fitness from baseline to 18-month follow-up. The results of this study indicate that availability of exercise equipment and engaging in short bouts of exercise may improve long-term weight loss. This study also demonstrates that accumulating exercise through short bouts of exercise is sufficient to reap health benefits such as decreased cardiovascular risk factors and increased fitness level.

Some researchers have speculated that perhaps different types of exercise would promote better long-term weight loss. Wadden and colleagues¹⁵ conducted an investigation to study this notion by randomizing obese participants to one of four groups: 1) diet alone, 2) diet plus aerobic training, 3) diet plus strength training, or 4) diet with aerobic and strength training combined. After 48 weeks of treatment, there were no differences between any of the groups on measures of weight, body composition, and energy expenditure. This study suggests that type of exercise does not have a differential effect on weight regain and long-term weight loss.

Another new direction in exercise and behavioral weight-loss programs is the amount of exercise recommended for long-term weight loss. Recent studies have suggested that weight-loss maintenance may require much more activity than the typically recommended weekly goal of 1,000 calories expended through exercise.⁶ Given that exercise is a predictor of long-term weight loss,¹⁶ researchers have been interested in determining exactly how much exercise is associated with weight maintenance.

In a descriptive study of 784 participants of a national registry of successful weight losers, it was found that participants who lost an average of 30 kg and kept off at least 13.6 kg for an average of 5.5 years reported exercising at a very high level.¹⁷ Specifically, participants expended an average of 2,800 kcal per week through physical activity. An example of this level of exercise would be brisk walking for 1 hour (or 4 miles) every day of the week. Other recent studies have also concluded that successful long-term weight loss may require a much higher level of physical activity than is usually recommended. A secondary analysis in the Jakicic et al. study¹⁴ revealed that participants who exercised more than 200 minutes per week had greater weight loss at 18 months than those who exercised 150–200 minutes per week. Participants who exercised less than 150 minutes per week had the least weight loss. This dose-response effect should be considered when recommending exercise for long-term weight loss.

Two recent studies examined the effect of encouraging participants to self-monitor their behavior during the winter holidays, which is considered a "high-risk" time of the year in terms of weight control. Half of the participants enrolled in a weight-loss program that utilized self-monitoring were asked to complete detailed self-monitoring records during 2 weeks from before Christmas to after the New Year.¹⁹ This group also received additional phone calls and daily reminders to self-monitor. The other half was not instructed to change their self-monitoring behavior in any way. After the holiday season, the group that focused on self-monitoring had lost an average of 2 pounds while the other group had gained 2 pounds. A similar study conducted by Baker and Kirschenbaum²⁰ studied participants of a ongoing weight-loss program and compared the consistency of self-monitoring during three holiday weeks versus seven nonholiday weeks. They found that only participants in the most consistent self-monitoring quartile lost weight over the holiday weeks. Thus, these studies emphasize the importance of self-monitoring in behavioral weight-loss programs, particularly during high-risk times.

In a similar study conducted by Wing and colleagues,²² overweight individuals enrolled in a weight-loss program were randomized to one of four groups: 1) a standard behavioral treatment that served as the control group, 2) a standard treatment group that also received meal plans (i.e., a daily menu of the exact type and amount of foods to be eaten) and relevant grocery lists, and 3) a standard treatment group that received food for five breakfasts and five dinners each week for which they paid $25 per week, or 4) same as group 3 but the participants did not have to pay for the food. Results revealed that the three experimental groups (groups 2–4) lost more weight at 6 months and 18 months compared to the control group (group 1). However, there were no significant differences among groups 2–4. The authors concluded that structured meal plans and grocery lists were the most effective components of these treatments.²²

A similar finding was reported by Klem et al.²⁴ who recently studied the acceptability of three weight- gain prevention treatment programs and found that women aged 25–34 preferred a correspondence course or a no-treatment control group over a group format. The group format, however, produced the greatest weight loss after 10 weeks of treatment, although this difference was not found at the 6-month follow-up.

Studies examining the long-term effect of weight-gain prevention interventions have not been as promising. In a 3-year weight-gain prevention study of more than 1,200 participants, Jeffery and French²⁵ randomized participants to one of three groups: 1) no-contact control, 2) education through monthly newsletters, or 3) education plus incentives for participation. Initially, the intervention groups gained weight at a slower rate. However, at the 3-year follow-up there were no differences between groups in term of weight gain. This study suggests that more intensive strategies may be needed to prevent weight gain in adults.

Women who have recently given birth are considered another high-risk population in terms of weight gain. In a recent study by Leermakers and colleagues,²⁶ new mothers who had retained a weight gain of at least 6.8 kg above their pre-pregnancy weight were randomly assigned to a correspondence weight-loss intervention or a no-treatment control group. These researchers found that participants who received the correspondence treatment lost significantly more of their excess postpartum weight than the no-treatment control group (79% vs. 44%). Preventing excess weight gain during pregnancy and developing interventions to help women lose excess postpartum weight deserve further attention.

The weight-gain prevention studies described above have been aimed at select populations. There have also been studies examining how to prevent weight gain in communities.

For example, French and colleagues²⁷ monitored the effect of changing the price of low-fat snacks in vending machines. There was a 4-week baseline period followed by a 3-week intervention followed by a 3-week post-intervention (return to baseline). They found that when low-fat snack prices were reduced by 50%, the proportion of low-fat snacks purchased increased from 26% to 46%.

Another environmental intervention study examined the effect of reducing the prices of fruit and salad by 50% in a workplace cafeteria and increasing the numbers of fruits and salad items that were available.²⁸ Three weeks of baseline observation were followed by 3 weeks of intervention (reduced prices and increased availability), which were followed by 3 weeks of the original condition. It was found that fruit and salad purchases increased threefold during the intervention period with women being more likely to choose these foods. These studies suggest that workplace cafeterias and public vending machines may be useful in large-scale nutrition interventions.

Manipulating environmental cues to increase physical activity has also been examined. Andersen and colleagues²⁹ placed signs beside escalators suggesting that individuals use the adjacent stairs for either health- or weight-related reasons. They found that stair use increased from 4.8% to 6.9% and 7.2%, respectively. Older individuals appeared to be more affected by the signs and increased their stair use from 5.1% to 8.1% with a health-related sign and to 8.7% with a weight-related sign. Interestingly, it was found that lean individuals used the stairs more often at baseline compared to overweight individuals (5.4% vs. 3.8%). However, the signs were equally effective in increasing stair use in both normal- weight and overweight individuals. Overall, this study demonstrated that a simple intervention such as posting a sign encouraging stair use can increase physical activity.

The availability of exercise equipment has been identified by some researchers as a major barrier to exercise. Jakicic and colleagues³⁰ examined the relationship of exercise equipment in the home and physical activity level. These researchers found a significant correlation between number of pieces of exercise equipment and self-reported exercise in women. This relationship was not found for men. However, when the sample was separated into quartiles, it was found that the quartile with the most equipment reported the greatest amount of exercise. Thus, owning exercise equipment may facilitate a higher level of activity. Similarly, Sallis et al.³¹ has shown a correlation between living near an exercise facility and actual activity levels. It remains unclear, however, whether more active people choose to live closer to exercise sites or whether easy access to exercise leads to increased levels of activity.

Given the beneficial effects of behavioral weight-loss treatment on medical conditions such as diabetes and cardiovascular disease, researchers continue to search for innovative ways to improve treatment outcomes and weight-loss maintenance. Some new directions in behavioral weight-loss treatment programs include placing an emphasis on self-monitoring during high-risk times, providing meal plans and grocery lists, prescribing multiple short bouts of activity, encouraging "lifestyle" activity, and encouraging a higher level of exercise for long-term weight loss.

Weight-gain prevention is another area of research receiving some attention. In addition, community interventions that manipulate the environment to help individuals eat healthful foods and exercise more have achieved some success and warrant further attention to address the widespread epidemic of obesity.