Invité par Carole Knibbe (Eq. DO-IT), le lundi 16 octobre de 13 à 14h, nous avons eu le plaisir d’écouter Samuel Bernard pour un séminaire scientifique à Lyon Sud (salle Confluences au RDC du bâtiment Cens-Eli 2D) intitulé :
« Implication of lipid turnover for the control of energy balance »
Il vient de publier, avec Kirsty Spalding du Karolinska Institute, une étude de modélisation sur la dynamique de prise et perte de poids, qui adresse une question polémique : est-ce que la nature des macronutriments ingérés est importante, ou bien est-ce juste le nombre de calories qui compte ?
Résumé: The ongoing obesity epidemic is a consequence of a progressive energy imbalance. The
energy-balance model (EBM) posits that obesity results from an excess in food intake and
circulating fuels. A reversal in causality has been proposed recently in the form of the
carbohydrate-insulin model (CIM), according to which fat storage drives energy imbalance.
Under the CIM, dietary carbohydrates shift energy use in favour of storage in adipose tissue.
The dynamics of lipid storage and mobilisation could therefore be sensitive to changes in
carbohydrate intake and represent a measurable component of the CIM. To characterise
potential changes in lipid dynamics induced by carbohydrates, mathematical models were
used. Here we propose a coherent mathematical implementation of the CIM (energy
deposition model, CIM-EDM), which includes lipid turnover dynamics. Using lipid turnover
data previously obtained by radiocarbon dating, we build two cohorts of virtual patients and
simulate lipid dynamics during aging and weight loss. We identify clinically testable lipid
dynamic parameters that discriminate between the CIM-EDM and an energy in, energy out
implementation of the EBM (EBM-IOM). Using a clinically relevant two-month virtual trial,
we additionally identify scenarios and propose mechanisms whereby individuals may
respond differently to low carbohydrate diets.
energy-balance model (EBM) posits that obesity results from an excess in food intake and
circulating fuels. A reversal in causality has been proposed recently in the form of the
carbohydrate-insulin model (CIM), according to which fat storage drives energy imbalance.
Under the CIM, dietary carbohydrates shift energy use in favour of storage in adipose tissue.
The dynamics of lipid storage and mobilisation could therefore be sensitive to changes in
carbohydrate intake and represent a measurable component of the CIM. To characterise
potential changes in lipid dynamics induced by carbohydrates, mathematical models were
used. Here we propose a coherent mathematical implementation of the CIM (energy
deposition model, CIM-EDM), which includes lipid turnover dynamics. Using lipid turnover
data previously obtained by radiocarbon dating, we build two cohorts of virtual patients and
simulate lipid dynamics during aging and weight loss. We identify clinically testable lipid
dynamic parameters that discriminate between the CIM-EDM and an energy in, energy out
implementation of the EBM (EBM-IOM). Using a clinically relevant two-month virtual trial,
we additionally identify scenarios and propose mechanisms whereby individuals may
respond differently to low carbohydrate diets.