How sustainable are hypocaloric and balanced diets for weight loss?

Background Promoting healthy diets with low environmental impact is pivotal. The EAT-IT diet aligns with the EATLancet Commission, tailored to Italian food habits. However, a comparison with weight loss diets has not been done. This cross-sectional study compares EAT-IT with historical diets of an urban nutritional care facility. Objective To compare conventional hypocaloric and balanced weight-loss diets with the sustainable EAT-IT diet, investigating their alignment, the influence of BMI and sex on EAT-IT adherence, to optimize the EAT-IT diet for weight management. Methods 4032 patients (72% female, median age 49y, BMI 29 kg/m2) received hypocaloric diets based on Mediterranean principles (51% carbohydrates, 31% lipids, 0.9 g/kg body weight protein, 17 g/1000 kcal fiber), following Italian dietary guidelines. Results Linear regression revealed lower EAT-IT alignment in males (-2.6%, p < 0.001) and a small BMI effect on food group adherence (0.4%, p = 0.005). Only 44% of prescribed food groups were in line to EAT-IT. Protein sources (fish 13%, red meat 13%) were generally higher than EAT-IT, except for legumes (26%) and nuts (10%) prescribed in lower quantities and frequencies, as well as vegetable oil (12%) and fresh fruits (11%). Complex carbohydrates-rich foods (13% bread, 12% pasta/cereals) and vegetables (21%) were prescribed in higher quantities in hypocaloric diets, being more aligned with the EAT-IT pattern. Conclusions Protein sources, being less sustainable, pose challenges in hypocaloric diets. Differences in consumption of vegetable foods were found according to sex and BMI, highlighting the struggle to meet EAT-IT sustainability criteria. Reconciliation between sustainable and hypocaloric dietary interventions is crucial.