USE OF LIPIDS: OXIDATION OR STORAGE?

The stability of body weight and composition requires an equilibrium between the intakes and outputs of energy and macronutrients. Fat mass depends on the equilibrium between the input and output of lipid but also on the metabolic fate of lipids (oxidation or storage). Examination of metabolic pathways and of their regulation shows that cells have efficient biochemical and molecular mechanisms to stimulate acutely and on the long term carbohydrate oxidation, lipogenesis and lipid storage and to inhibit lipid oxidation. On the contrary, the ability of cells to acutely stimulate lipid oxidation is limited. These differences in regulation of lipid and carbohydrate metabolism are also present at the whole body level. The ability to increase lipid oxidation in response to an increased lipid intake is still more reduced in obese subjects. Despite numerous attempts to develop pharmacological approaches, modifications of dietary intakes and physical exercise remain the best ways to reduce lipid storage and to increase fat oxidation.