Carbohydrates and energy balance

Area of Science:

• Nutritional Science
• Human Metabolism
• Dietary Studies

Background:

• Early 1970s: Carbohydrates (CHOs) linked to overconsumption and fat deposition.
• Current View: CHOs perceived to protect against these metabolic consequences.
• Shift in Understanding: Requires re-evaluation of CHO's role in energy balance.

Purpose of the Study:

• Evaluate the evidence behind the changing interpretation of carbohydrates' metabolic effects.
• Compare energy density, metabolic handling efficiency, and appetite regulation of CHOs versus other macronutrients.
• Assess the impact of CHOs on energy intake and fat deposition in Western diets.

Main Methods:

• Analysis of energy content (delta Hc) and digestibility of carbohydrates.
• Evaluation of the energetic efficiency of de novo lipogenesis from dietary CHOs.
• Comparison of macronutrient effects on satiety and autoregulation of stores via oxidation.
• Review of studies on high-carbohydrate (HC) diets and their impact on energy intake and weight management.

Main Results:

• CHOs are the least energy-dense macronutrients with variable digestibility; fiber increases this variability.
• De novo lipogenesis from CHOs is inefficient and limited in high-fat Western diets.
• Macronutrient oxidation hierarchy: protein > CHOs > fat.
• Satiety hierarchy: protein > CHOs > fat, especially when fat is energy-dense.
• High-carbohydrate diets do not consistently promote spontaneous weight loss.

Conclusions:

• The energetic handling and satiety effects of CHOs are less concerning than previously thought, especially in Western diets.
• While excess CHO intake can promote fat storage, de novo synthesis is limited.
• Current evidence does not support the idea that CHO-rich diets or those with sweeteners cause spontaneous weight loss.