Nowadays, there’s considerable discussion around the pros and cons of high-carb diet and low-carb/high-fat diet. The majority of people are aware of the importance of carbohydrate and fat in producing energy during working out. But they know less about the merits of high- or low-carb diets.
Low-carb/high-fat diets are widely recognized as a good way to improve performance and metabolism. But these claims are largely unproven, if not wrong.
Recently, a study compared the impact of a high-carb diet and a high-fat diet in more detail. The study concentrated particularly on the muscles’ ability to use oxygen, which is essential when using different energy sources.
After completing a glycogen depleting training session, eight men started either a high-fat diet (73% fat, 22% protein and 5% carbohydrate) or high-carb diet (80% carbohydrate, 10% fat, 10% protein) for six days. They then carried out an exercise test on days five and six, which involved cycling at low intensity and building up to high intensity (80% lactate threshold). During this test, oxygen uptake was assessed, along with carbohydrate and fat oxidation.
Researchers discovered that those on high-fat diets took longer to adapt to taking in more oxygen as intensity increased than those following high-carb diets. This indicates a lower capacity for muscle blood flow and oxygen delivery, which causes the muscle to use carbohydrate at a lower rate.
Therefore, if your target is improving performance, your form could suffer if you’re on a high-fat diet for more than six days.
Periodizing carbs is a good approach to take. Have lots of of carbohydrate when performance is your target but lower your intake when doing lower-intensity, shorter sessions or on rest days.