ABSTRACT
ABSTRACT Background: Several mechanisms, including excessive hunger, account for patients' difficulties in maintaining weight loss and dietary changes after caloric restriction. Objective: To evaluate the effect of short-term high-fiber calorie-restricted diet in appetite-regulating hormones, and hunger and satiety sensations in women with obesity. Methds: In a randomized controlled trial study, thirty women with body mass index (BMI) higher than 30 kg/m2, and aged from 20 to 50 years were hospitalized following a calorie-restricted diet (1000 kcal/day) for three days. The experimental group (n=15) received high-fiber diet and the control group (n=15), conventional diet. Body weight, BMI, resting energy expenditure (REE), acylated and total ghrelin, leptin, insulin and glucose, and hunger and satiety sensations were evaluated. Linear regression models with mixed effects (fixed and random effects) helped to assess the variables between the two groups and within the groups. Results: Body weight and BMI decreased in both the experimental and control groups (P<0.001). After the high-fiber diet, postprandial acylated ghrelin (P=0.04), glucose (P<0.001), insulin (P=0.04), and leptin (P=0.03) levels as well as the HOMA-IR index (P=0.01) decreased, whereas satiety improved (P=0.02). Obese women that followed the conventional diet had increased body fat percentage (P=0.04) and lower REE (P=0.02). The two diets did not differ in terms of hunger sensation. Conclusion: A short-term high-fiber diet improves satiety sensations and metabolic parameters while suppressing postprandial acylated ghrelin (60 minutes) and maintaining the resting energy expenditure.
RESUMO Contexto: Vários mecanismos, incluindo a fome excessiva, são responsáveis pelas dificuldades dos pacientes em manter a perda de peso e mudanças na dieta após a restrição calórica. Objetivo: Avaliar o efeito da dieta de curta duração rica em fibras e com restrição calórica nos hormônios reguladores do apetite e nas sensações de fome e saciedade em mulheres com obesidade. Métodos: Em um estudo randomizado controlado, 30 mulheres com índice de massa corporal (IMC) superior a 30 kg/m2 e com idade entre 20 e 50 anos foram hospitalizadas seguindo dieta com restrição calórica (1000 kcal/dia) por 3 dias. O grupo experimental (n=15) recebeu dieta rica em fibras e o grupo controle (n=15), dieta convencional. Foram avaliados peso corporal, IMC, gasto energético de repouso (GER), grelina acilada e total, leptina, insulina e glicose e sensações de fome e saciedade. Modelos de regressão linear com efeitos mistos (efeitos fixos e aleatórios) ajudaram a avaliar as variáveis entre os dois grupos e dentro dos grupos. Resultados: O peso corporal e o IMC diminuíram tanto no grupo experimental quanto no controle (P<0,001). Após a dieta rica em fibras, os níveis de grelina acilada pós-prandial (P=0,04), glicose (P<0,001), insulina (P=0,04) e leptina (P=0,03), bem como o índice HOMA-IR (P=0,01) diminuiu, enquanto a saciedade melhorou (P=0,02). Mulheres obesas que seguiram a dieta convencional apresentaram aumento do percentual de gordura corporal (P=0,04) e menor GER (P=0,02). As duas dietas não diferiram em termos de sensação de fome. Conclusão: Uma dieta rica em fibras de curto prazo melhora as sensações de saciedade e os parâmetros metabólicos, suprimindo a grelina acilada pós-prandial (60 minutos) e mantendo o gasto energético de repouso.
ABSTRACT
Objective To compare the levels of short-chain fatty acids produced by high-fiber diet and low-fiber diet in the intestinal metabolism of mice for exploring the effects of different fiber diets on the activation and function of microglia in mouse brain. Methods Mice fed with low-fiber and high-fiber diets were detected for the levels of three major short-chain fatty acids (acetic acid, propionic acid, butyrate) in the cecum. The distributions of microglia in the brain of different diet mice were compared by immunofluorescence. Real-time fluorescence quantitative PCR was used to detect expressions of genes associated with microglia activation in mouse brain between the above two groups of mice. Results The acetate level in the cecum of mice in high fiber diet group was higher than that of mice in low fiber diet group. There were no significant differences between the two groups in the levels of propionic acid and butyrate and the number and distribution of microglia. However, the levels of microglial activation-associated inflammatory cytokines such as IL-1β, IL-6, TNF-α, IL-12, CCL2, CCL5 and CCL7 mRNA were higher in high fiber diet group than in low fiber diet group after the intracranial stimulation by LPS. Conclusion The quantity of fiber in the diet after weaning can affect the maturation and activation of microglia in the brain, which may because of different levels of acetic acid after metabolism of different dietary structures by the intestinal flora.