Does the stomach shrink in cases of starvation?

Stomach Shrinkage During Starvation

During starvation, the stomach does not physically shrink in size, but metabolic and functional changes occur that affect hunger perception and digestive capacity.

Metabolic Adaptations During Starvation

• Starvation causes non-specific alterations in substrate metabolism similar to those observed in inflammation, characterized by reduced carbohydrate oxidation and increased lipid oxidation 1
• These metabolic changes are reversible when adequate nutritional support is provided 1
• The body progressively selects fat as the primary fuel source during starvation, with ketoacid levels becoming elevated in the blood over the first week 2
• The brain begins to preferentially use ketones instead of glucose, which helps spare protein, though negative nitrogen balance still occurs 2

Gastrointestinal Changes During Starvation

• Acute gastric dilatation, rather than shrinkage, has been observed in chronically starved individuals who suddenly consume large meals 3
• Structural and functional changes in the stomach due to chronic starvation can affect gastric motility and emptying 3
• In animal studies, starvation has been associated with gastric lesions, with the location varying based on the weight of the animal and genetic factors 4

Hunger Regulation During and After Starvation

• Sickness-associated anorexia (SAA) during infection involves decreased food intake as part of the body's adaptive response 1
• After periods of starvation, humans typically experience hyperphagia (increased hunger and food intake) as an autoregulatory mechanism attempting to restore body weight 5
• This post-starvation hyperphagia is determined by feedback mechanisms from both fat and lean tissues - the greater the depletion of these tissues, the stronger the hyperphagic response 5

Metabolic Rate and Energy Conservation

• Starvation results in an energy-conserving reduction in metabolic rate as an adaptive response 6
• During starvation, there are decreases in cardiac output, blood flow to various organs (including the heart, skin, white adipose tissue, and muscles), and regional oxygen consumption 6
• Resting energy expenditure may vary depending on inflammatory activity and nutritional status, but is generally similar to healthy subjects or slightly increased when calculated in relation to fat-free mass 1

Clinical Implications

• In patients with chronic diseases like Crohn's disease, changes in substrate metabolism during periods of reduced intake are similar to those in starvation and are not disease-specific 1
• Understanding the metabolic effects of feeding and fasting is vital in treating and predicting outcomes in various clinical conditions 1
• Current "one size fits all" feeding regimens in clinical settings could potentially harm patients by interfering with conserved physiological responses to reduced intake 1

Nutritional Considerations

• An intake of 25-30 kcal/kg/day is usually adequate to meet energy requirements for patients recovering from starvation 1
• After starvation, there is a risk of "overshooting" body fat during refeeding, which has implications for both obesity treatment and nutritional rehabilitation 5
• Insulin appears to be the principal regulatory hormone during starvation, with decreased levels of active T3 potentially playing a role in sparing calories by decreasing metabolic needs 2