The anti-obesity effect of starch in a whole grain-like structural form

Obesity is a risk factor for many chronic diseases, and the anti-obesity effect of starch in a whole grain-like structural form (WGLSF) prepared through co-gelation with oat β-glucan and alginate was studied using high-fat (HF) induced obese male C57BL/6J mice. In vitro human fecal fermentation of WGLSF-starch showed a slower rate of fermentation and a higher production of butyric acid (132.0 μmol per 50 mg sample) when compared to the physical mixture counterpart of starch, β-glucan, and alginate (PM) (110.5 μmol per 50 mg) or β-glucan itself (96.2 μmol per 50 mg). The body weight gain of obese mice fed with a HF-WGLSF diet was significantly reduced (42.0% lower than the HF group, 30.2% lower than the physical mixture) with decreased cell size in white adipose tissue and similar levels of serum lipid profiles to the control of the low-fat (LF) group. Western blotting experiments showed the down-regulated lipogenic transcription factor of SREBP-1c and fatty acid synthase (FAS), but the lipid-oxidation related transcription factors of peroxisome proliferator-activated receptor-α (PPAR-α) and phosphorylated AMP-activated protein kinase (p-AMPK) were up-regulated. Energy metabolism analysis revealed increased lipid-sourced energy expenditure with higher heat production and respiratory exchange ratios. Consistently, the expression of hypothalamic pro-opiomelanocortin (POMC), favoring energy expenditure, was increased significantly while the neuropeptide Y (NPY) was reduced. Thus, the increased energy expenditure stimulated by starch in a whole-grain-like structural form is responsible for the reduced body weight gain of obese mice fed with a high fat-based diet.