Pathophysiology and Comprehensive Intervention of Obesity in the Elderly: From Hormonal Changes to Diet and Exercise Prescriptions
I. Pathophysiological characteristics of obesity in the elderly
Hormone Level Changes in the Elderly (1) Growth Hormone: Growth hormone secretion gradually declines with age in the elderly, often resulting in reduced skeletal muscle mass, abnormal blood lipids, and increased abdominal fat. Relative growth hormone deficiency is one of the intrinsic factors causing obesity in the elderly. (2) Leptin: Leptin resistance is common in obese individuals. Serum leptin levels increase with age, promoting fat accumulation in the abdomen and internal organs, while also causing a decline in muscle mass and function. (3) Insulin: Abdominal fat increases with age, and most obese elderly individuals experience a decrease in insulin sensitivity. Increased abdominal fat is the main cause of insulin resistance.
Changes in body composition with aging are accompanied by a decrease in muscle mass and an increase in fat content. Muscle strength begins to decline around age 30, accelerating after age 60. Decreased basal energy expenditure exacerbates fat accumulation, especially visceral fat. Fat cell infiltration of muscle tissue reduces muscle strength, leading to a decline in physical activity levels in older adults. Older adults are more prone to sarcopenic obesity.
Metabolic disorders and abdominal fat accumulation promote insulin resistance, increasing the risk of cardiovascular disease, diabetes, hyperuricemia, and chronic kidney disease. II. Key Points for Obesity Management in the Elderly
Diagnostic criteria: BMI ≥ 28 kg/m² is considered obese. Considering the characteristics of abdominal obesity, a waist circumference ≥ 90 cm for men and ≥ 85 cm for women is recommended as the diagnostic criteria. The WHO recommends a body fat percentage of ≥ 25% for men and ≥ 33% for women. Bioelectrical impedance analysis can be used to determine sarcopenia (the cutoff point for sarcopenia is 7.0 kg/m² for men and 5.7 kg/m² for women).
Behavioral therapy: In principle, the BMI of older adults should ideally be no lower than 20.0 kg/m² and no higher than 26.9 kg/m². Weight loss goals should be set on an annual basis, aiming to lose 5% to 10% of body weight within a year. Self-monitoring includes weighing oneself daily, recording diet, and avoiding prolonged sitting.
Dietary management principles: (1) Control total energy intake. It is recommended to reduce by 300-500 kcal/day, and the daily energy supply should not be less than 1000 kcal. (2) Adequate protein intake. The intake should account for 15%-20% of total energy, or 1.0-1.5 g/kg body weight, and the proportion of high-quality protein should reach 50%. (3) Limit dietary fat intake. Control it to 20%-30% of total energy, choose vegetable oil, and limit high-cholesterol foods. (4) Adequate carbohydrate intake (40%-30 g). (5) Limit salt (35 g) and purines. (6) Use less oil for cooking (steaming, boiling, and roasting), and abstain from alcohol.
Exercise management: Appropriate exercise can reduce abdominal fat and increase muscle mass. The ultimate goal is at least 150 minutes of aerobic exercise per week and resistance training 2-3 times per week. Exercise should be increased gradually.