Nutritional interventions are one of the most promising non-pharmacological approaches that attenuate aging. Continuous calorie restriction (CR), the most studied intervention, extends lifespan in animals and, in humans, slows biological aging and improves healthspan (e.g., disease risk factors, quality of life). In the largest clinical trial of CR in humans (CALERIE 2), adherence to 25% CR waned to ~12% CR over 2 years, which questions the practicality of such interventions over longer periods. CALERIE 2, however, did not benefit from a more advanced approach, namely a Just-in-Time Adaptive Intervention (JITAI), which tailors and optimizes the intervention for each subject. JITAIs strive to provide individuals with the right type and amount of personalized support when necessary by adapting the intervention delivery to the present adherence, needs and environment of the subject. This is accomplished by the use of mobile health (mHealth) technology (smartphones, sensors) to objectively evaluate intervention adherence in real-time and to adapt intervention delivery to each individual over time. The near real-time collection of ecologically valid and objective data from people in their free-living environment dramatically improves the ability to promote adherence and subject engagement.~Newer approaches, such as time-restricted eating (TRE), where food intake is restricted to less than a 10-hour period of the day, may also benefit aging. Short-term pilot studies of TRE showed that, independent of CR, eating over a 6-hour window that began in the morning significantly improved diabetes and cardiovascular risk factors (healthspan) and biomarkers of primary aging (e.g., autophagy, oxidative stress, nutrient sensing). The long-term feasibility of TRE is unknown, and it is unclear if TRE interventions with JITAI designs enhance intervention feasibility and adherence in the context of healthy aging.~The current trial will examine the feasibility and preliminary efficacy of two CR and two TRE interventions to modulate healthspan and biomarkers of aging in healthy, young (25-45 years) individuals. In a 5-arm pilot and feasibility trial, 90 people without obesity (BMI 22-29.9 kg/m2) will be randomized to either ad libitum Control, Traditional CR, Adaptive CR, Traditional TRE, or Adaptive TRE for 24 weeks (n=18/group) for six months
The purpose of this study is to conduct a five-arm pilot and feasibility trial in healthy, young individuals without obesity to evaluate the feasibility and efficacy of dietary intervention approaches to slow mechanisms of aging.