2.4 Macronutrient balance and energy metabolism

Macronutrient balance is crucial for optimal health and energy metabolism. The right mix of carbs, proteins, and fats supports body composition, metabolic health, and disease prevention. Imbalances can lead to nutrient deficiencies and health issues.

Energy metabolism is influenced by diet composition, physical activity, and individual factors like genetics and hormones. Different dietary approaches for weight management and disease prevention manipulate macronutrient balance to achieve specific health outcomes.

Macronutrient balance for health

Recommended macronutrient distribution ranges (AMDR)

• Macronutrient balance refers to the proportion of carbohydrates, proteins, and fats in the diet, typically expressed as percentages of total energy intake
• The recommended macronutrient distribution ranges (AMDR) for adults:
  • 45-65% of energy from carbohydrates
  • 10-35% from protein
  • 20-35% from fat
• Consuming a balanced ratio of macronutrients ensures an adequate supply of essential nutrients (vitamins, minerals, essential fatty acids, and amino acids)
• Macronutrient balance supports optimal body composition (lean muscle mass and body fat percentage) and helps maintain metabolic health (insulin sensitivity and glucose control)

Consequences of imbalanced macronutrient intakes

• Imbalanced macronutrient intakes may lead to various health issues:
  • High-fat diets may result in nutrient deficiencies (fiber, vitamins, and minerals), metabolic disturbances (insulin resistance and dyslipidemia), and increased risk of chronic diseases (cardiovascular disease and certain cancers)
  • High-protein diets may strain kidney function, alter calcium balance, and increase the risk of dehydration
• The optimal macronutrient balance may vary depending on individual factors such as age, sex, physical activity level, and health status (pregnancy, lactation, or presence of chronic diseases)
• Achieving macronutrient balance through a diverse diet containing whole grains (quinoa and brown rice), lean proteins (poultry and fish), healthy fats (avocados and nuts), and ample fruits and vegetables is crucial for long-term health and disease prevention

Factors influencing energy metabolism

Dietary factors

• Energy metabolism refers to the processes of energy expenditure and storage in the body, which are influenced by multiple factors
• Diet composition, particularly the proportion and quality of macronutrients, affects energy metabolism:
  • High-protein diets may increase diet-induced thermogenesis (energy expenditure during food digestion and absorption) and satiety (feeling of fullness), leading to increased energy expenditure and reduced energy intake
  • High-carbohydrate diets, especially those rich in simple sugars (refined grains and sugary beverages), can lead to rapid blood glucose fluctuations and altered insulin sensitivity, affecting energy storage and utilization
  • High-fat diets may promote fat storage and reduce insulin sensitivity, particularly when consumed in excess of energy needs
• The quality of macronutrients (refined vs. whole grains, saturated vs. unsaturated fats) also influences energy metabolism and overall health

Non-dietary factors

• Physical activity is a major determinant of energy expenditure, with higher levels of activity leading to increased energy metabolism and improved body composition (increased muscle mass and reduced body fat)
• Individual variations in energy metabolism are influenced by factors such as:
  • Basal metabolic rate (BMR), which is largely determined by body size, composition, age, and sex
  • Genetic variations in metabolic pathways and hormonal regulation, which can affect energy balance and body weight
  • Hormonal status, particularly thyroid hormones (regulate metabolic rate) and insulin (regulates glucose uptake and storage), which regulate energy metabolism and storage
• Adaptive thermogenesis, a process by which the body adjusts energy expenditure in response to changes in energy intake or physical activity (starvation or overfeeding), can influence long-term energy balance and weight management

Dietary approaches for weight management vs disease prevention

Weight management approaches

• Different dietary approaches for weight management often manipulate macronutrient balance to achieve specific outcomes
• Low-fat diets, which typically emphasize carbohydrates and limit fat intake, have been associated with modest weight loss and improved lipid profiles (reduced LDL cholesterol), but long-term adherence may be challenging
• Low-carbohydrate diets, such as the ketogenic diet, restrict carbohydrate intake (typically <50 g/day) and promote higher fat and protein consumption, leading to rapid weight loss and improved insulin sensitivity in the short term, but long-term safety and sustainability are controversial
• High-protein diets, which allocate a greater proportion of energy to protein (typically 25-35%), may enhance weight loss, preserve lean body mass, and improve cardiometabolic risk factors (blood pressure and lipid levels), but excessive protein intake may have adverse effects on kidney function and bone health
• Intermittent fasting approaches, which manipulate the timing of food intake rather than macronutrient balance (16/8 method or 5:2 diet), have shown promise for weight loss and metabolic health, but long-term effects and applicability to diverse populations require further research

Disease prevention approaches

• Mediterranean-style diets, characterized by a balance of whole grains, lean proteins, healthy fats (olive oil and fatty fish), and abundant plant foods (fruits, vegetables, and legumes), have been consistently associated with reduced risk of chronic diseases (cardiovascular disease, type 2 diabetes, and certain cancers) and long-term weight management
• Plant-based diets, which emphasize whole plant foods and minimize animal products, have been linked to lower risk of chronic diseases and improved weight control, likely due to their high fiber content, low energy density, and favorable nutrient profiles (antioxidants and phytochemicals)
• The effectiveness of any dietary approach depends on individual adherence, sustainability, and overall nutritional adequacy, emphasizing the importance of personalized nutrition strategies based on individual preferences (food culture and taste preferences), lifestyle (time constraints and cooking skills), and health status (presence of food allergies or intolerances)