A study to investigate the effect of a low-ED prescription (consume ≥10 foods ≤ 1.0 kcal/g and ≤ 2 foods ≥ 3.0 kcal/g per day) versus an energy balance prescription (consume a daily energy intake at estimated energy needs for maintenance) on weight loss maintenance.

Obesity increases the risk of several health conditions. Weight loss of 5-10% of initial weight reduces the risk of several diseases. This degree of weight loss is achievable in behavioral obesity programs. However, about 33% of initial weight loss is regained within one year and very little weight loss is maintained within three to five years. Thus, new strategies improving long-term weight loss maintenance are needed. One dietary strategy that increases self-reported satiation and satiety is consuming a low energy density (ED) diet. A low-ED diet allows a greater weight of food relative to total energy to be consumed, which is the proposed mechanism for the enhanced self-reported satiation and satiety found with low-ED meals. Research has shown that when participants are served low-ED meals, while total weight of food consumed does not change, meal energy intake decreases. Importantly, when low-ED meals are consumed across several days, reduced energy intake continues to occur, showing no degree of energy intake compensation. To address the gaps regarding the relationship between dietary ED and weight loss maintenance, we propose to conduct a randomized controlled trial (RCT) examining the effect of a low-ED prescription and its proposed mechanisms on weight loss maintenance.

The primary hypotheses are:

1. Low-ED will have less weight regain than Energy Balance at 22 months.

   a. Weight regain at 10, 16, and 22 months will be examined to determine if differences occur between conditions.

2. Low-ED will consume a lower ED diet, less energy and percent energy from fat, and greater grams from solid food and fiber than Energy Balance at 10, 16, and 22 months.

   The secondary hypotheses are:

3. Identify mechanisms (mediators) by which reducing ED improves long-term lower energy intake, thus:

   1. Low-ED will self-report lower hunger and greater satiation and satiety during EMA than Energy Balance at 10, 16, and 22 months.

Inclusion Criteria:

• Age between 18 and 70 years
• Body mass index (BMI) between 27 and 45 kg/m2

Exclusion Criteria:

• Report a heart condition, chest pain during periods of activity or rest, or loss of consciousness on the Physical Activity Readiness Questionnaire
• Individuals reporting joint problems, prescription medication usage, or other medical conditions that could limit exercise will be required to obtain written physician consent to participate
• Report being unable to walk for 2 blocks (1/4 mile) without stopping
• Report major psychiatric diseases or organic brain syndromes.
• Are currently participating in a weight loss program and/or taking weight loss or appetite regulation medication or lost > 5% of body weight during the past 6 months
• Have had bariatric surgery for weight loss or are planning to have bariatric surgery in the next 22 months
• Intend to move outside of the metropolitan area within the time frame of the investigation
• Are pregnant, lactating, < 6 months post-partum, or plan to become pregnant during the investigation
• Report not being able to consume meal replacements

To participate in the weight loss maintenance phase, participants will need to lose equal to or greater than 8% of their body weight from the baseline measure at the conclusion of the 4-month weight loss phase.