This pilot study will randomize 34 patients with hypertension and obesity to either time-restricted feeding alone or a commitment device to encourage time-restricted feeding, including a commitment pledge, involvement of a supportive partner, setting of implementation intentions, and multiple daily reminder text messages. The intervention will last 12 weeks, followed by a 6-week follow-up period. The primary outcome is adherence to the IF regimen, captured via daily text message, over 18 weeks

1.1. Non-Pharmacologic Interventions to Improve Blood Pressure Control: Despite the wide availability of multiple classes of antihypertensive agents, compelling data that blood pressure (BP) lowering reduces mortality and cardiovascular events, and decades of public health campaigns, half of American adults with hypertension do not achieve adequate BP control. Randomized controlled trials of interventions to improve BP control in patients with hypertension have largely focused on home blood pressure monitoring, nurse- or pharmacist-lead education and medication titration, and/or financial incentives. Though many of these interventions improve short-term blood pressure control, they are cost-additive to health systems, post-intervention data is mixed, and none have been widely implemented.

Though consensus guidelines recommend dietary changes to improve hypertension control, with a particular recommendation in favor of the DASH (Dietary Approaches to Stop Hypertension) diet, very few U.S. patients adhere to this complex dietary pattern. The DASH diet reduced systolic BP (SBP) by 11 mmHg in randomized controlled trials in which participants were provided with food, and 4 mmHg in a study testing a 6-month, 18-visit intensive lifestyle intervention intended to promote the DASH diet; however, BP control was not sustained 12 months after the end of the intensive intervention.

1.2. Effect of Intermittent Fasting on Metabolic Parameters: In contrast to the DASH diet, intermittent fasting (IF) is a dietary pattern that emphasizes temporal restriction of caloric intake rather than restricting the number of calories and/or changing the types of foods eaten. The simplest and most popular variation of IF involves restricting caloric intake to an 8-hour period each day, and consuming no calories for the other 16 hours (so-called 16:8 time-restricted feeding). In animal studies, IF has been shown to activate cellular pathways with potential disease-modifying benefits in a number of conditions. In small human studies, IF is associated with a reduction in SBP by 5-10 mmHg, LDL cholesterol by ~8 mg/dl, and weight by ~ 3 kg, though none of the studies of a time-restricted feeding regimen included concurrent controls. Some patients report that IF is easier to initiate and maintain than other dietary patterns, though this has not been tested empirically.

1.3. Commitment Devices to Promote Healthy Behaviors: Commitment devices are centered in theoretical research that posits a planner-doer framework, wherein an individual can be conceptualized as dual sub-selves: The planner, who cares about long-term well-being; and the doer, who cares only for the present and prioritizes immediate payoffs. Conflict between the motivations and priorities of the planner and the doer sub-selves results in failure to follow-through with a plan when the moment to act arrives. Commitment devices are mechanisms by which the planner sub-self constrains the actions of their future doer sub-self by making certain choices more costly. Hard commitments impose a financial penalty for failing to follow through on the commitment, and soft commitments impose a psychological penalty. Hard commitments have been shown to change health behaviors, as in a study where smokers forfeited money deposited in a savings account if they failed to quit smoking after 6 months. However, monetary losses may not be attractive to many people, and effective soft commitment devices may be more appealing.

Pre-clinical research suggests that both intra- and interpersonal commitments might be useful components of a soft commitment device. Intrapersonal commitments have also been framed as implementation intentions, or specific plans as to where, how, and/or when an action will be taken. In small experiments, smokers who set a quit date were more likely to quit, and college students who set a date and time to visit a vaccination clinic were more likely to receive their vaccination. Interpersonal commitments leverage social networks, so that the penalty involves letting down a support partner. Involvement of social networks has been used to increase physical activity and improve control of weight and blood glucose in patients with obesity and diabetes. Social networks have been used explicitly within the context of commitment devices to encourage deposits in a savings account in a study of Chilean micro-entrepreneurs who either attended or did not attend a weekly peer support group meeting. Weight loss studies encouraging participants to exercise and change their eating behavior have employed commitment devices, including some that leveraged the involvement of family members or friends of the participant, with mixed results.

1.4 Rationale for the IFAST Study: The IF dietary pattern, though not inspired by behavioral economic concepts, is structured to take advantage of them and thus may be particularly amenable to a robust commitment device intervention. Changing one's eating patterns to a complex new diet is a cognitively intense process that requires active consideration of complex information multiple times per day, leading to cognitive overload and impaired decision-making. By contrast, IF, especially time-restricted feeding, is cognitively very simple. This simplicity may help participants avoid cognitive overload, initiate the dietary pattern and adhere over the long term.

This study seeks to test how a robust soft commitment device, incorporating both intra- and interpersonal commitments, affects uptake and adherence to an intermittent fasting dietary pattern, as compared with control, in patients with obesity and hypertension

Inclusion Criteria:

• Age 18 or older
• Body mass index > 30 kg/m2
• Systolic blood pressure > 150 mmHg
• Owns a smartphone or tablet operating the iOS or Android operating system

Exclusion Criteria:

• Unable or unwilling to provide informed consent, including but not limited to cognitive or language barriers (reading or comprehension)
• Type 1 diabetes
• Use of insulin or insulin secretagogues (sulfonylureas, metaglinides)
• Use of medications that require food intake
• Ongoing use of pharmacologic therapy for weight loss
• Self-reported eating disorder
• Other medical condition that could be harmed by intermittent fasting as judged by study physician
• Anticipated life expectancy less than 6 months
• Any other reason why it is not feasible to complete the entire 6-month study

18 weeks