Hunger not of the belly kind

Hunger and thirst are fundamental physiological drives crucial for maintaining homeostasis and ensuring the survival of both humans and animals. These drives are regulated through complex interactions between the brain, hormones, and sensory receptors.
Hunger arises when the brain detects changes in the body's nutrient levels, including glucose, lipids, amino acids, and hormones such as ghrelin and leptin. The hypothalamus plays a central role in hunger regulation. The lateral hypothalamus acts...

Pyloric obstruction, also referred to as gastric outlet obstruction, is a condition characterized by narrowing or blockage at the pylorus—the muscular valve regulating the flow of stomach contents into the duodenum. When this passage becomes impaired, the stomach cannot effectively empty its contents into the small intestine. This disruption leads to a range of gastrointestinal symptoms, including early satiety, bloating, epigastric pain, postprandial nausea, persistent vomiting, and...

Short-term regulation of food intake primarily involves neural signals from the gastrointestinal (GI) tract, blood nutrient levels, and GI tract hormones. Communication between the gut and brain via vagal nerve fibers plays a significant role in evaluating the contents of the gut. Clinical studies have shown that protein ingestion produces a more prolonged response in these nerve fibers compared to an equivalent amount of glucose. Additionally, the activation of stretch receptors caused by GI...

During the initial hours of fasting, the body uses up its glycogen stores as an energy source. Once these glycogen reserves are depleted, the body begins breaking down stored triglycerides and structural proteins. During this stage, glycerol becomes a key substrate for gluconeogenesis, while free fatty acids undergo beta-oxidation to provide energy for tissues, such as skeletal muscle. In the fasting state, the body spares protein breakdown as much as possible to conserve muscle and structural...

Hypoglycemia is a blood glucose level below 70 mg/dL. It commonly occurs in individuals using insulin or insulin-secreting drugs, but may also arise in non-diabetic conditions. People with type 1 diabetes are at the highest risk because they depend on exogenous insulin. People with type 2 diabetes are also at risk, especially when treated with insulin or medications such as sulfonylureas, which increase insulin release regardless of blood glucose levels. It develops when insulin levels exceed...

Without prolonged fasting, healthy individuals maintain blood glucose levels above 3.5 mM due to a well-adapted neuroendocrine counterregulatory system that effectively prevents acute hypoglycemia, a potentially life-threatening condition. The primary clinical scenarios for hypoglycemia encompass diabetes treatment, inappropriate production of endogenous insulin or insulin-like substances by tumors, and the use of glucose-lowering agents in non-diabetic individuals. Notably, hypoglycemia in the...