A 2-Year Calorie Restriction Intervention Improves Diet Quality Without Compromising Nutritional Adequacy: The CALERIE Trial

Abstract

Background: The Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE) was the first randomized controlled trial of calorie restriction (CR) on biomarkers of aging and cardiometabolic health in humans without obesity. Objective: To determine diet quality and nutritional adequacy during a 2y calorie restriction intervention among healthy adults without obesity. Design: CALERIE phase 2 was a multi-site, randomized controlled trial of 2y of CR vs. ad libitum (AL) control. CR participants received extensive dietary education and support. Food diaries were completed at baseline and months 6, 12, 18, and 24 and analyzed using NDSR. Diet quality was evaluated using the PANDiet diet quality index. Nutritional adequacy was defined using sex- and age-specific Estimated Average Requirement (EAR) or Adequate Intake (AI) criteria for each nutrient. Results: 220 participants completed baseline assessments and were randomized (145 CR, 75 AL; 70% women, age 38±7 y, BMI 25.1±1.7 kg/m2); 86% completed the 2y study. The level of calorie restriction achieved averaged 11.9±0.7% during the 2y intervention. Diet quality improved in the CR group (BL 74.3±5.1%; CR average 76.3±5.3%, p < 0.0001), but not in the AL group ( p < 0.0002 between groups). Nutritional adequacy improved modestly in CR, but not in AL. More than 90% of CR participants achieved 100% of EAR or AI during CR for protein, carbohydrate, 6 of 12 vitamins (A, B1, B2, B3, B6, B12), and 5 of 9 minerals (copper, iron, phosphorus, selenium, sodium). Nutrients for which <90% of participants achieved adequacy included fiber, omega-3 fatty acids, vitamins B5, B9, C, E, and K, and the minerals calcium, magnesium, potassium, and zinc. Conclusion: A 2y CR intervention designed to promote healthy aging and comprised of comprehensive nutrition counseling promoted improvements in diet quality and maintenance or improvements in nutritional adequacy. This research was supported by grants U01AG020478, U01AG020480, U01AG020487, U01AG022132, U24AG047121, R33AG070455, and R01AG071717 from the National Institute on Aging. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.