The availability of fat to the muscles increases after fat-rich meals, as well as during physical activity and in the hours after the exercise bout. Fat is an important source of energy for the muscles, but besides the direct stimulation of fat combustion as substrate it also acts as a signalling molecule which stimulates increased production of proteins involved in fat metabolism, whereby the fat metabolic capacity is increased.

This review article in the highly recognized journal Nature Reviews Endocrinology discusses, on the basis of human studies, how both the consumption of a fat-rich diet and endurance exercise training bring about improvements in the fat-burning ability of the muscles and stimulate many of the same improvements in the ‘orchestra’ of different proteins that control fat combustion in the muscles. These are proteins involved in the uptake of fat from the blood into the muscle, the transport of fat into the combustion units of the muscles – the mitochondria – and the burning of fat in the fat-burning reaction, known as β-oxidation, in the mitochondria. The result of changes in these proteins, brought about by repeated physical activity (training) and repeated intake of fat-rich meals, is that the system becomes better to deal with available fat – be it from the diet or from body fat stores – and more of the fat is burned. This means that you can both eat and exercise your way to better fat-burning ability.

“Part of the key to achieving healthy, efficient metabolism in people with metabolic disorders such as type 2 diabetes may lie in improving fat-burning ability and the potential to switch from burning sugar to burning fat (and vice versa) depending on which of the two energy sources is available and most advantageous in the given situation.”

Excess weight is typically characterized by an impaired ability to burn fat in the muscles, and individuals with overweight often do not show the same upward adjustment of the ability to burn fat when fat intake is high. This impaired ability to burn fat is a factor in these individuals’ increased risk of developing metabolic diseases such as type 2 diabetes. Fortunately, though, individuals with overweight appear to benefit from endurance exercise training, too. In individuals with overweight, endurance exercise training also improves the ability to burn fat, as seen in normal weight individuals, and exercise training appears to improve the ability to shift between combustion of dietary carbohydrates and combustion of dietary fat, which may reduce the risk of developing metabolic disease. Part of the key to achieving healthy metabolism in individuals with metabolic disorders such as type 2 diabetes may lie in improving fat-burning ability and the ability to switch from burning sugar to burning fat (and vice versa) depending on which of the two energy sources is available and most advantageous in the given situation.

CONTACT
Andreas M. Fritzen (PhD, Postdoc) and Anne-Marie Lundsgaard (PhD, Postdoc)
Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen

Their email addresses are:
amfritzen@nexs.ku.dk
amlundsgaard@nexs.ku.dk

READ THE ARTICLE HERE
Fritzen, A. M., Lundsgaard, A.-M., & Kiens, B. (2020). Tuning fatty acid oxidation in skeletal muscle with dietary fat and exercise. Nature Reviews Endocrinology, 16(12). https://doi.org/10.1038/s41574-020-0405-1
Published: 22 September 2020.