High-Fat or Very High-Fat Diet Administered After Weaning: Which Is More Harmful to Muscle Metabolism?

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Medicine and Science in Sports and Science





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PURPOSE: Diets with a high-fat content (45% lipids) or very high-fat content (60% lipids) in combination with highly palatable sugary drinks are used to induce experimental obesity in rats. However, establishing an animal model of obesity with causes and characteristics similar to human ones is still a challenge. Besides, its effects on metabolism are not yet fully elucidated. The present study investigated the effects of two models of obesity induced by a high-fat or very high-fat diet associated with fructose drink on muscle metabolism and hormonal parameters of rats. METHODS: Twenty-seven male Wistar rats (21 days of age, 43±2g) were divided into 3 groups (n=9/group): (HF group - 45% lipids) or very high-fat (VHF group - 60% lipids) diet with fructose-drink (fructose 10%) for hydration, and control rats (C group - AIN93G) and water. The diets were administered for 70 uninterrupted days. Data were analyzed using one-way analysis of variance (ANOVA, p<0.05). RESULTS: The body mass gain (p<0.001), final body weight (p<0.001), the adipocyte area in inguinal depots (p<0.001), serum insulin (p=0.001), and leptin (p=0.001) were higher in the HF group, followed by VHF compared to C group. Lee Index was higher only in HF compared with C (p=0.02). The soleus (p=0.01), gastrocnemius, and EDL muscles presented lower relative mass in HF e VHF compared with C (p<0.001). The relative mass of the anterior tibialis and quadriceps were lower in HF compared to C and VHF, with VHF lower than C (p<0.001). Both HF and VHF diets promoted muscle wasting, suggesting damage to the metabolism. The visceral (retroperitoneal, omental, perirenal) and inguinal (subcutaneous) adipose depots were higher in HF and VHF than in the C group (p<0.01). The HF showed higher HOMA2-IR values (p=0.004) than C and VHF, suggesting insulin resistance condition. HOMA-CFβ (p=0.001) was similar between HF and C, and both were higher than VHF, indicating damage to beta-pancreatic cells. CONCLUSIONS: The data suggest that HF diet administered with fructose induced muscle wasting as well as hormonal changes similar to human obesity. In addition, it is possible that this obesity model has generated some type of sarcopenic obesity.

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Metabolism; Diet


Biochemical Phenomena, Metabolism, and Nutrition | Dietetics and Clinical Nutrition



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