From the Guidelines
During prolonged starvation, it is crucial to prioritize metabolic adaptations that preserve muscle mass, and the most effective approach is to ensure protein intake is above 1 g/kg/day up to 1.5 g/kg/day, as recommended by recent guidelines 1. When considering metabolic adaptation to preserve muscle mass in prolonged starvation, several physiological changes occur to minimize muscle loss. Initially, the body depletes glycogen stores and shifts to using fat as its primary fuel source. A key adaptation is the decreased reliance on protein breakdown for gluconeogenesis, with the body increasing ketone production from fatty acids to supply energy to the brain and other tissues.
Some key points to consider in preserving muscle mass during prolonged starvation include:
- Maintaining or increasing the level of physical activity to support muscle mass, physical function, and metabolic pattern, including individualized resistance exercise in addition to aerobic exercise to maintain muscle strength and muscle mass 1.
- Ensuring adequate protein intake, as mentioned, to support muscle preservation.
- If oral food intake has been severely decreased for a prolonged period, increasing nutrition slowly over several days to prevent refeeding syndrome is essential 1.
- Encouraging physical activity and exercise in individuals at risk of malnutrition to maintain or improve muscle mass and function, as supported by strong consensus in geriatric guidelines 1.
The most critical recommendation for preserving muscle mass during prolonged starvation is to maintain adequate protein intake and engage in regular physical activity, including resistance and aerobic exercises, to support muscle function and metabolic health 1.
From the Research
Metabolic Adaptation to Preserve Muscle Mass in Prolonged Starvation
- The human body has an adaptive starvation response that allows for survival during long-term caloric deprivation 2
- During starvation, the body initially consumes gluconeogenic amino acids and then shifts to lipid metabolism, marked by a surge in plasma nonesterified fatty acids 2
- This metabolic adaptation helps preserve muscle mass by reducing the breakdown of muscle proteins and promoting the use of alternative energy sources, such as fat 2
- Studies have shown that intermittent enteral nutrition, rather than continuous tube feeding, may be beneficial in preserving muscle mass during prolonged starvation 3
- Additionally, limiting nutrient intake during the first 48-72 hours of acute illness may be beneficial, followed by intermittent enteral nutrition targeting 20-25 cal/kg/day 3
Nutritional Management of Starvation
- Total parenteral nutrition may be necessary in the early stages of starvation, particularly in patients with short bowel syndrome 4
- The total parenteral nutrition diet should consist of a majority of calories from fat, followed by protein, and the remaining as carbohydrates, with added vitamins, minerals, and trace elements 4
- Treatment goals should focus on early transition to enteral nutrition, followed by oral feeds, to promote intestinal adaptation and absorption 4
- Pharmacologic treatment and the use of specific nutrients and growth factors may also stimulate intestinal absorption and adaptation 4
Importance of Nutrition in Preserving Muscle Mass
- Adequate nutrition is essential for preserving muscle mass, particularly in older adults, who require the same protein intake and micronutrients as younger patients 5
- Malnutrition can lead to a range of complications, including increased risk of infections, poor wound healing, and decreased quality of life 5
- Nutrition should be considered during every ward round, and the multidisciplinary team should maintain an awareness and responsibility for managing malnutrition 5