From the Guidelines
The girl is likely in a fasting state characterized by early starvation metabolism, with her body relying on alternative energy sources, such as gluconeogenesis and lipolysis, to maintain blood glucose levels and provide energy for vital functions. Her body has depleted its readily available glucose stores (glycogen) in the liver and muscles, and has begun to break down muscle protein and fat stores to produce glucose and ketone bodies 1. This metabolic state is similar to that experienced by individuals with diabetes who fast for religious reasons, such as during Yom Kippur or Ramadan, who are at increased risk for hypoglycemia, dehydration, hyperglycemia, and ketoacidosis 1. Some key physiological changes that may be occurring in the girl's body include:
- Depletion of glycogen stores in the liver and muscles
- Increased gluconeogenesis to produce glucose from amino acids, glycerol, and lactate
- Increased lipolysis to produce ketone bodies as an alternative fuel source
- Elevated glucagon and decreased insulin levels to promote glucose production and fat mobilization
- Possible symptoms such as hunger, fatigue, irritability, difficulty concentrating, and headaches or lightheadedness due to these metabolic changes. It is also important to consider the risk of dehydration, particularly in hot and humid climates or with excessive physical activity, as well as the potential for orthostatic hypotension, syncope, and falls 1.
From the Research
Physiologic State After 24 Hours of Fasting
The girl's physiologic state after 24 hours of not eating can be represented by the following factors:
- Metabolic switch from glucose to fat and ketones (G-to-K) [ 2 ]
- Deactivation of mTOR regulated nutrient signalling pathways and activation of the AMP protein kinase, triggering cell repair and inhibiting anabolic processes [ 2 ]
- Potential improvement in cognition due to the rise of ketones, which can be used for brain energy [ 2 ]
- Reduced appetite due to the production of ketones [ 2 ]
Potential Health Effects
The girl may experience:
- Weight loss and improved metabolic health [ 3 ]
- Improved health outcomes due to the influence of intermittent fasting on circadian biology, the gut microbiome, and modifiable lifestyle behaviors [ 3 ]
- Increased life and health span, enhanced intrinsic defences against oxidative and metabolic stresses, and decreased cardiovascular risk [ 2 ]
Gastrointestinal Symptoms
The girl may experience gastrointestinal symptoms such as:
- Postprandial fullness, abdominal distention, abdominal pain, gastric distension, and early satiety [ 4 ]
- Altered esophageal motility, postprandial distress syndrome, superior mesenteric artery syndrome, irritable bowel syndrome, and functional constipation [ 4 ]
- Nausea and vomiting, which can be caused by various pathophysiological processes, involving gastrointestinal and non-gastrointestinal causes [ 5 ]
- Abdominal bloating and distension, which can be characterized by symptoms of trapped gas, abdominal pressure, and fullness [ 6 ]