Examinando por Autor "Ravussin, Eric"

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    Baseline body fat percentage is associated to weight and fat mass gain from high-fat overfeeding over 8 weeks
    (Oxford University Press; Endocrine Society, 2025-04-21) Galgani, Jose E.; Fernández-Verdejo, Rodrigo; Bray, George A.; Smith, Steven R.; Ghosh, Sujoy; Javvadi, Pravalika; Ravussin, Eric
    Background & aims: Epidemiological data suggest that participants with lower vs. higher body mass index (BMI) resist exposure to the obesogenic environment. To test this, we analyzed the relationship between overfeeding-induced weight and fat mass gains with baseline BMI and body fat percentage. Methods: In this controlled intervention study, 34 men (age: 26±5 y old; BMI: 25.5±2.4 kg/m2, body fat [DXA]: 19.3±5.1%) consumed for 8 weeks 40% more energy than needed at weight maintenance. The energy costs of weight and fat mass gain were calculated as the 8-week excess energy consumed divided by weight or fat mass gain. Energy expenditure (baseline and after overfeeding) was determined using a metabolic chamber and doubly labeled water. Transcriptomic analysis was conducted from abdominal subcutaneous adipose tissue samples. Results: Body weight increased 7.2±2.1 kg and fat mass 4.0±1.4 kg. There was no statistical association between baseline BMI and weight and fat mass gains. However, baseline body fat percentage was significantly associated with weight (r=0.57) and fat mass (r=0.59) gains. Body fat percentage was also statistically associated with energy cost of weight (r=-0.38) and fat mass (r=-0.40) gains. Metabolic adaptation in energy expenditure (adaptive thermogenesis) was unrelated to the energy cost of weight and fat mass gains. Transcriptomics analysis showed that high energy cost of weight gain was associated with up-regulation of inflammation-related pathways. Conclusion: Body fat percentage at baseline was inversely associated with overfeeding-induced weight and fat gain resistance. The underlying compensatory response appears unrelated to changes in energy expenditure.
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    Effects of ketone bodies on energy expenditure, substrate utilization, and energy intake in humans
    (American Society for Biochemistry and Molecular Biology, 2023-09-11) Fernández-Verdejo, Rodrigo; Mey, Jacob T.; Ravussin, Eric
    Recientemente se ha prestado atención al potencial de los enfoques cetogénicos para regular el equilibrio energético, ya que las cetonas pueden influir tanto en el gasto como en la ingesta de energía. En esta revisión narrativa, resumimos la evidencia más relevante sobre el papel de la cetosis en el gasto de energía, la utilización de sustratos y la ingesta de energía en humanos. Consideramos diferentes estrategias para inducir la cetosis, como el ayuno, la manipulación dietética y las fuentes exógenas de cetonas. En general, la cetosis no tiene una influencia importante en el gasto energético, pero promueve un cambio en la utilización del sustrato hacia la oxidación de los cuerpos cetónicos. Las estrategias para inducir la cetosis mediante la reducción de la disponibilidad de carbohidratos en la dieta (p. ej., dietas cetogénicas) no influyen de forma independiente en la ingesta de energía, por lo que son igualmente efectivas para perder peso que las dietas con mayor contenido de carbohidratos. Por el contrario, la ingesta de triglicéridos de cadena media y ésteres de cetonas induce cetosis y parece aumentar el gasto energético y reducir la ingesta energética en el contexto de una alta disponibilidad de carbohidratos. Estas últimas estrategias conducen a una pérdida de peso ligeramente mayor. Desafortunadamente, distinguir los efectos de las diversas estrategias cetogénicasper se de los efectos de otras respuestas fisiológicas no es posible con los datos humanos disponibles. Se necesitan estudios hospitalarios altamente controlados que utilicen estrategias específicas para aislar los efectos independientes de las cetonas para abordar adecuadamente esta brecha de conocimiento.
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    Leveraging shared variation among traits for the discovery of genetic variants in complex phenotypes such as obesity
    (Wiley; The Obesity Society, 2025-06-01) Fernández-Verdejo, Rodrigo; Hughes, David; Ravussin, Eric
    Identifying genetic variants associated with obesity is critical forunderstanding the role of genetics and its interaction with the envi-ronment in the regulation of body weight. Hundreds of genetic vari-ants have been identified so far, mostly associated with body massindex (BMI). Nevertheless, given the complex pathogenesis andthe evolving definition and diagnosis of obesity, exploring traitsbeyond BMI becomes crucial to advancing the field. Obesityresults from a prolonged positive energy balance, during which energyintake exceeds energy expenditure. Therefore, identifying geneticvariants associated with energy balance-related traits should provideadditional insight into the genetic basis of obesity.