307 - Human Starvation (Dr Hoffer lecture)

Starvation is the physiological condition created in the body by chronically insufficient food intake

Physiological and Pathological

• Its a disease:
• Protein energy malnutrition (PEM)
• Starvation disease
• Starvation- related malnutrition

Due to a lack of adaptation

• Reduced body weight
• Adipose tissue depletion
• Muscle wasting and decreased strength
• Reduced respiratory and cardiac muscular capacity
• Skin thinning
• Deceased metabolic rate
• Hypothermia
• Apathy
• Edema
• Immunodeficiency

• Reduced protein store
• ↓↓ Skeletal muscle mass
• ↓ Heart muscle mass
• ↓ Respiratory muscle mass 
• ↓ Protein reserve

• Reduced metabolic rate
• Hypotension
• Bradycardia
• Hypothermia

• Protein and energy balance = 0
• Normal serum albumin

• Continuing protein and fat loss
• Hypoalbuminemia
• Immune deficiency

• > 25%
• The Canadian Malnutrition Task Force reports prevalence as 45%

• 1. Starvation related malnutrition (SRM)
• 2. Chronic disease-related malnutrition (CDRM)
• 3. Acute disease related malnutrition (ADRM)

• Simple, uncomplicated PEM
• Muscle atrophy and fat depletion caused by solely by starvation

Cachexia: Muscle atrophy and fat depletion caused by a combination of starvation and chronic systemic inflammation

• Not necessarily an existing disease per se
• Rapid severe muscle catabolism induced by critical illness of severe trauma or sepsis
• Likely mitigated by sufficient protein provision
• Patient may or may not have existing PEM

• PEM
• Halts the loss of body mass despite continuing starvation

• Cessation of fat loss
• Cessation of lean tissue

• Reduced ↓ mass of metabolically active tissue (muscle mass) (slow, and takes weeks)
• Reduced ↓ energy expenditure per unit active tissue (fast, takes days)

• Reduced work of moving
• Reduction of voluntary movements

• Reduced heart rate and blood pressure
• Reduced muscle tone

• Diminished ↘ lean tissue mass
• More efficient retention of dietary protein
• Lean tissue mass stabilizes despite continued low protein intake

• Involves:
• Reduced energy "requirement" for homeostasis
• Reduced protein"requirement" for homestasis

Survival

• Lean tissue loss
• Fatigue and inactivity
• Immunodeficiency
• Reduced tolerance to stress

• Pathological starvation
• Obese people benefit from reducing their excessive body store of adipose tissue to a desirable size
• To accomplish this goal, they have to consumme less energy for a long time (aka they must starve)

• Muscle atrophy
• Lowered basal metabolic rate
• Fatigue
• Apathy
• Hypothermia

Common cause in the world is involuntary food deprivation

• Anorexia
• Pain 
• Nausea
• Chewing and swallowing problems
• Poverty
• Gastrointestinal obstruction
• Dysgeusia (when things taste bizarre)

• starvation disease combined with chronic low grade systemic inflammation

Cachexia

• Acute phase response (hypoalbuminemia and increased C-reactive protein concentration)
• Increased muscle protein catabolism
• Anorexia
• Impaired adaptation to starvation

• Anorexia
• Pain
• Nausea
• Chewing and swallowing problems
• Poverty
• Gastrointestinal obstruction

• Chronic infection
• Autoimmune disease
• Chronic kidney
• Heart or lung disease
• Certain Cancers

• Cardinal features of starvation disease are generalized muscle atrophy and fat depletion but they are easy to detect
• 2 reasons:
• Patients with in-hospital starvation often have a normal BMI
• Patients commonly have multiple reasons for muscle atrophy

• Muscle atrophy
• (Fat depletion)

• 1. Cachexia - systemic inflammation
• 2. Hormone excess or deficiency
• 3. Old age - sarcopenia 9 loss of muscle w/age)
• 4. Protein energy malnutrition (PEM) - starvation disease
• 5. Inactivity - disuse atrophy
• 6. Neuromusclar disease

• Starvation can be Physiological and Pathological
• Pathological starvation: Leads to the disease called PEM
• PEM: common + difficult to treat disease in Montreal hospitals
• SRM: simples, uncomplicated PEM (as in AN)
• CDRM: PEM + chronic systemic inflammation that:
•            ↑ muscle protein catabolism, induces anorexia and impairs the adaptation to starvation