Investigating Metabolic and Psychological Adaptations in a Clinical Trial

Effect of Meal Timing and Dietary Changes on Metabolic and Behavioral Factors Involved in the Food Insecurity-Obesity Paradox

This study aims to explore how food insecurity, a lack of consistent access to enough food, may lead to changes in the body that make it harder to lose weight. The investigators are testing whether providing women experiencing food insecurity with a stable, healthy, and personalized meal plan can improve their metabolism and reduce their motivation to eat unhealthy foods. The hypothesis is that addressing food insecurity with a predictable diet can lower a person's respiratory quotient (a measure of how the body uses energy), promote fat burning, and improve overall health. This research will improve the understanding for how food insecurity contributes to obesity and may lead to better solutions for managing weight in individuals facing these challenges.

Women who experience food insecurity have unpredictable access to food and often miss meals and go hungry, but paradoxically are at a 50% greater risk for developing obesity than women who are food secure. This is due in part to metabolic and behavioral factors involved in food insecurity. Research suggests unpredictable access to food is associated with: 1) a high respiratory quotient (RQ) indicative of substrate oxidation that favors storage of fat and burning of carbohydrates; 2) an increase in fuel efficiency and a reduced thermic effect of food (TEF); 3) higher relative reinforcing efficacy of food (RREFOOD), due in part to periodic food deprivation that results from unpredictable access to food and being hungry, and 4) a short temporal window that involves making decisions that focus on meeting immediate versus long-term goals, as assessed by delay discounting (DD). While people with food insecurity and obesity should modify their diet, an RQ that favors storage of fat coupled with a reduced TEF, high RREFOOD and high DD may compromise the effects of traditional dietary approaches to weight loss. The goal of this pilot study is to examine the effects of providing a personalized, stable, predictable, low carbohydrate, low glycemic index, high protein, low energy dense diet on changes in metabolic and behavioral factors that characterize low-income women with food insecurity who have obesity, using a novel stepped wedge design. This work extends our research on behavioral and metabolic factors involved in food insecurity, and will provide strong pilot data for a randomized, controlled trial of a novel dietary approach that target factors involved in food insecurity and obesity that can improve weight control and reduce cardiometabolic risk factors. The investigators expect to screen at least 60 women, with an estimated screen failure rate of 80%. A goal for this pilot project is to provide effect sizes for future studies. The sample size was determined based on feasibility constraints, with the understanding that these results will serve as pilot data for a larger, fully powered randomized controlled trial.

Inclusion Criteria:

• Woman between the ages of 18-45.
• Premenopausal.
• Obese (BMI ≥ 30).
• Diagnosed with prediabetes (HbA1c: 5.7%-6.4%).
• Experiencing food insecurity (score of 2-6 on the six-item food insecurity questionnaire).
• Income below 300% of the household federal poverty threshold.
• Lives alone.

Exclusion Criteria:

• Actively planning to become pregnant (e.g., individuals trying to conceive or undergoing fertility treatment, based on self-report).

• Delivered a baby within the past 6 months (self-report).

• Non-ambulatory (e.g., individuals unable to walk independently or requiring a wheelchair for mobility).

• Intellectual impairment that would impact treatment adherence.

• Unmanaged mood disorders, substance use disorders, personality disorders, or a history of eating disorders, including:

  • Generalized anxiety disorder.
  • Depression.
  • Alcohol dependence.
  • Schizophrenia.
  • Anorexia nervosa, bulimia, or binge eating disorder within the past 6 months.

• Recent weight loss exceeding 5% of body weight within the past 6 months (self-report).

• Food allergies to study-related foods, including dairy, soy, nuts, or gluten.

• History of bariatric surgery or GLP-1 agonist use (self-report).

• Inability to read or write in English (self-report).

• Planned relocation out of the study area during the study timeframe (self-report).

• Uncontrolled diabetes (HbA1c > 9%) or hypertension (blood pressure > 160/100 mmHg), based on self-report or screening visit measurements.