Full-fat dairy vs. low-fat dairy with energy restriction for weight and metabolic outcomes in adults with overweight/obesity

BACKGROUND: Habitual dairy consumption reduces risk factors for obesity and its associated characteristics of the metabolic syndrome. OBJECTIVES: This study aims to describe the effect of adding 3 daily servings of full-fat dairy to the diet of adults with overweight and obesity, counseled to follow Canada's Food Guide (CFG). METHODS: A 12-wk single-blinded, parallel, randomized study was conducted in 74 participants [age: 36.55 ± 1.04 y; body mass index (BMI): 29.34 ± 0.43 kg/m] assigned to 1 of 3 groups: 1) low dairy energy restriction (LD-ER): 500 kcal restriction with ≤1 serving of low-fat dairy, 2) 3 dairy energy neutral (3D-EN): 500 kcal restriction replaced by 3 servings of full-fat dairy, and 3) 3 dairy ad libitum (3D-AL): no energy restriction with 3 servings of full-fat dairy. Changes in physiological outcomes and dietary intakes were measured over 12 wk. RESULTS: Body weight and BMI were reduced by treatment (P < 0.05) in LD-ER over the 12 wk (P > 0.05). In 3D-AL, a decrease (0.25 ± 0.34 cm) in hip circumference (P < 0.05) and in systolic blood pressure (2.72 ± 2.18; P < 0.05; SBP) was found at week 12. SBP also decreased in LD-ER (P < 0.05). Triglycerides increased in all groups at week 4 (P < 0.05) but returned to baseline by week 12. Neither treatment nor time affected waist circumference, fat and fat-free mass, resting metabolic rate, fasting blood cholesterol, and urine creatinine and urea (P > 0.05). Protein and calcium (P < 0.04) intakes were increased with time in 3D-EN and 3D-AL but not in LD-ER. Compliance with CFG, assessed by a food tracker, increased with time (77% by week 12). CONCLUSIONS: Frequent and daily consumption of full-fat dairy as part of a healthy diet is consistent with CFG. This study was registered at clinicaltrials.gov as NCT04399460 on 22 May, 2020 (https://www. CLINICALTRIALS: gov/study/NCT04399460).