Response to Letter to the Editor: “Twice as High Diet-Induced Thermogenesis After Breakfast vs Dinner on High-Calorie as Well as Low-Calorie Meals”

We thank Ken Ho for his remarks on our article. This second letter to the editor reveals a spirited need for discussion and underlines the significance of our findings. The argumentation by Ho is apparently based on a divergent view on the definition of diet-induced thermogenesis (DIT). In accordance with the current international scientific terminology, we define DIT as the increase in energy expenditure above the basal fasting level due to food intake (1, 2). The standard method to determine DIT in human experimental studies is indirect calorimetry, which we used to determine postprandial energy production, that is, conversion of the chemical free energy of nutrients into the chemical energy of adenosine triphosphate plus loss of some energy during the oxidation process (3). We neither stated nor “assumed that what was measured is solely heat energy.”

However, the proportion of energy required for digestion and transport of solid meals with complex carbohydrates, proteins, and lipids consumed per os in our study is certainly not negligible in contrast to the cited experiment by Ho, which administered a liquid solution composed of a mixture of D-glucose, essential amino acids, and lipids via enteral and parenteral application (4).

Notwithstanding, we could do a small thought experiment and assume that the higher DIT in the morning is due to an increase in nutrient storage, as Ho argues. This would mean that people who regularly eat an extensive breakfast in the morning are at a higher risk of developing obesity and, vice versa, that individuals predominantly having large dinner meals are less likely to be overweight. This contradicts the results of numerous prevailing studies of the last years. Higher energy consumption in the morning and lower consumption close to bedtime, for example, is associated with lower body mass index (BMI) (5). In addition, a 6-year prospective cohort study showed that consuming more of the daily energy intake at dinner predisposes to obesity (6). Similarly, another study revealed that breakfast eaters and those who consume breakfast as the largest meal, display a decreased BMI compared with breakfast skippers and individuals preferring dinner as the most extensive meal of the day (7).

However, irrespective of the definition and interpretation of DIT, our conclusion of a better metabolic status after breakfast compared with dinner is substantiated by another human experimental study demonstrating that having a higher proportion of calories at breakfast indeed leads to greater weight loss in obesity (8).

Abbreviations

Abbreviations
 
• BMI

  body mass index

 
• DIT

  diet-induced thermogenesis

Additional Information

Disclosure Summary: The authors have nothing to disclose.

References