Background/Objectives: A high-energy-density (HED) diet promotes body weight gain, fat accumulation, and gut dysbiosis, contributing to obesity. The aim of this study was to characterize the initial response to HED diet consumption, as well as identify any sex differences in body composition, systemic inflammation, gut microbiome, and fecal fat excretion in rats. Methods: Male and female Sprague-Dawley rats were fed a low-energy-density (LED) diet for 10 days and were then switched to an HED diet for four weeks. Food intake, body weight, and body composition were measured routinely. Serum samples were collected to measure inflammatory cytokines/chemokines. Fecal samples were collected for microbiome analysis and lipid content. Results: After the HED diet, all rats gained body weight and fat mass, with males exhibiting increased susceptibility to weight gain. Males displayed either a diet-induced obesity phenotype (DIO-P) or a diet-resistant (DR) phenotype, as characterized by their differential body weight gain. Males showed elevated TGF-β levels, while females exhibited increases in Interferon gamma-inducible protein 10 (IP-10), regulated on activation, normal T cell expressed and secreted (RANTES) protein, and basic fibroblast growth factor (FGFb). Changes in gut microbiota composition revealed a reduction in beneficial species, like Bacteroides uniformis and Parabacteroides distasonis, and an increase in species such as Akkermansia muciniphila. Sex differences in fat metabolism were shown in the greater fecal fat excretion observed in males. Conclusions: Our study demonstrates that short-term consumption of a high-energy diet elicits notable sex-specific differences in body weight, body composition, inflammatory markers, gut microbiota, and fat excretion in Sprague-Dawley rats. While we recognize that this study has a small sample size and a short-term intervention, our findings highlight the critical role of sex as a biological variable in diet-induced obesity research.

Obesity and type 2 diabetes are closely linked and often referred to as diabesity. Therapies of diabesity include improving intestinal health and reducing intake of fat and sugars. Diagnosis of diabesity-related metabolic disorders would involve monitoring of glucose and other factors. Nanocellulose, also known as cellulose nanomaterials, is emerging as a potential material for various applications. It has unique properties, such as high surface area, biodegradable, biocompatibility and tunable surface chemistry. In this review, we initially provided a brief description of differently produced nanocellulose and their potential applications in different areas, including therapeutics and diagnostics, by focusing on obesity and diabetes. Then, the uptake, absorption, distribution, metabolism and excretion of nanocellulose were discussed. Further, the mechanisms of nanocellulose in modulating diabesity were summarized by emphasizing the role of gut microbiota. Finally, we discussed gut microbiota-related health effects of nanocellulose, both beneficial and detrimental. It was found that the interactions between nanocellulose and gut were complex, with alterations of microbial composition, metabolic activity, and the immune functions both locally and systemically. There seemed to be many beneficial changes following short-term exposure to nanocellulose (e.g., increased beneficial bacteria and decreased pathogenic ones); however, some of these effects were no longer seen after long-term consumption. Importantly, long-term nanocellulose consumption may be associated with certain detrimental health effects, e.g., malnutrition and its associated neurotoxicity, although additional studies are needed to substantiate such health implications. This information is critical for developing safe and effective nanocellulose derivatives that can be applied in food and medicine as well as to harness the benefits of the gut microbiota.

Background/Objectives: Consumption of a high energy density diet (HED) leads to increased body weight and fat mass, gut dysbiosis, and obesity. The aim of this study was to characterize the initial response to HED consumption, as well as identify any sex differences, on body composition, systemic inflammation, gut microbiome, and fecal fat excretion in rats. Methods: Male and female Sprague-Dawley rats were fed a low energy density (LED) for 10 days and then were switched to HED for four weeks. Food intake was measured twice a week, body weight and body composition were measured weekly. Serum samples were collected to measure inflammatory cytokines/chemokines. Fecal samples were collected for microbiome analysis and lipid content. Results: Both males and females experienced increases in body weight, fat mass and fecal fat excretion, while males were more susceptible to significant weight gain, particularly in the diet-induced obesity-prone (DIO-P) group. Males showed elevated TGF-β levels, while females exhibited increases in IP-10, RANTES, and FGFb. Changes in gut microbiota composition revealed a reduction in beneficial species like Bacteroides uniformis and Parabacteroides distasonis and an increase in species such as Akkermansia muciniphila. Sex differences in fat metabolism were shown in the greater fecal fat excretion observed in males. Conclusions: Our study demonstrates that short-term consumption of a high-energy diet elicits notable sex-specific differences in body weight, body composition, inflammatory markers, gut microbiota, and fat excretion in Sprague-Dawley rats. These findings underscore the importance of considering sex as a biological variable in studies of diet-induced obesity and its metabolic consequences.