INS and obesity due to melanocortin 4 receptor deficiency: The results of these studies indicate that plants and plant-derived compounds improve obesity- or high-fat/high-sucrose diet-induced cognitive impairment through various mechanisms, including attenuation of neuroinflammation, improving central and peripheral insulin resistance, enhancing neurogenesis and neuroprotection, and affecting the synthesis and release of cognition-associated neurotransmitters (Figure 2).