Eating carbohydrate mostly at lunch and protein mostly at dinner within a covert hypocaloric diet influences morning glucose homeostasis in overweight/obese men

Purpose

To evaluate the effects of two dietary patterns in which carbohydrates and proteins were eaten mostly at lunch or dinner on body weight and composition, energy metabolism, and biochemical markers in overweight/obese men.

Methods

Fifty-eight men (30.0 ± 7.4 years; 30.8 ± 2.4 kg/m²) followed a covert hypocaloric balanced diet (?10 % of daily energy requirements) during 8 weeks. Subjects were randomly assigned to three groups: control diet (CT); diurnal carbohydrate/nocturnal protein (DCNP); and nocturnal carbohydrate/diurnal protein (NCDP). Main analyzed outcomes were weight loss, body composition, diet-induced thermogenesis (DIT), and glucose/lipid profile.

Results

In all groups, a significant decrease in body weight, BMI, and fat mass (kg and %) was verified, without differences between groups. Interestingly, within group analyses showed that the fat-free mass (kg) significantly decreased in NCDP and in CT after 8-week intervention, but not in DCNP. A detrimental increase in fasting glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA_IR) was verified only in DCNP, while NCDP and CT groups presented a non-significant reduction. Moreover, significant differences between DCNP and the other groups were detected for fasting insulin and HOMA_IR. After the adjustments, NCDP presented a significantly higher DIT and energy expenditure after lunch, compared with DCNP, but after dinner, there were no differences among groups.

Conclusion

Eating carbohydrates mostly at dinner and protein mostly at lunch within a hypocaloric balanced diet had similar effect on body composition and biochemical markers, but higher effect on DIT compared with control diet. Moreover, eating carbohydrates mostly at lunch and protein mostly at dinner had a deleterious impact on glucose homeostasis.