Nutritional quality of calorie restricted diets in the CALERIE™ 1 trial

Objectives: The aim was to determine the nutritional adequacy of calorie restricted (CR) diets during CR interventions up to 12 months. Methods: The Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE (TM)) phase 1 trial consisted of 3 single-site studies to test the feasibility and effectiveness of CR in adults without obesity. After baseline assessments, participants who were randomized to a CR intervention received education and training from registered dietitians on how to follow a healthful CR diet. Food diaries were completed at baseline and during the CR interventions (similar to 6, 9, and 12 months) when participants were self-selecting CR diets. Diaries were analyzed for energy, macronutrients, fiber, 11 vitamins, and 9 minerals. Nutritional adequacy was defined by sex- and age-specific Estimated Average Requirement (EAR) or Adequate Intake (AI) criteria for each nutrient. Diet quality was evaluated using the PANDiet diet quality index. Results: Eighty-eight CR participants (67% women, age 40 +/- 9 y, BMI 27.7 +/- 1.5 kg/m(2)) were included in the analysis. Dietary intake of fiber and most vitamins and minerals increased during CR. More than 90% of participants achieved 100% of EAR or AI during CR for 2 of 4 macronutrients (carbohydrate and protein), 6 of 11 vitamins (A, B1, B2, B3, B6, B12), and 6 of 9 minerals assessed (copper, iron, phosphorus, selenium, sodium, zinc). 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, and potassium. The PANDiet diet quality index improved from 72.9 +/- 6.0% at baseline to 75.7 +/- 5.2% during CR (p < 0.0001). Conclusion: Long-term, calorie-restricted diets were nutritionally equal or superior to baseline ad libitum diets among adults without obesity. Our results support modest calorie restriction as a safe strategy to promote healthy aging without compromising nutritional adequacy or diet quality.

Automated summary

The study aimed to assess the nutritional adequacy of long-term calorie-restricted (CR) diets. The results showed that calorie-restricted diets were nutritionally equivalent or superior to ad libitum diets in terms of nutritional adequacy and diet quality among adults without obesity.