Originally Posted by
thehammerdog
just returned from 25 mile ride feeling good. I ate handful of peanuts, coffee glass of iced tea.
been riding early since Covid often on empty stomach.
feeling good, losing weight. by cutting back on my food I'm feeling better. but dumb founded. so what is the science here?
Overnight your body converts fat into carbs via gluconeogenesis, so you should generally have 25g of blood sugar (100 calories), 100g of glycogen in your liver (400), and 400g (1600) in your muscles noting you can't move glycogen between muscle fibers.
Exercise is powered by an intensity, training, and diet dependent mix of carbs and body fat. A little fat helps satiety and protein alertness although they can't be digested fast enough to provide energy.
At high intensity, recruiting fast twitch muscle fibers allows using the glycogen in them and endurance is too limited to run out.
At lower intensity, only 1/4 to 1/3 of your calories come from carbs.
Most people with some training don't need to eat on or before rides under four hours, and past that you only need to keep up with the 1/4 to 1/3 of your calories coming from carbs.
Rob Gray's metabolic test results from the wattage list. FTP was 292W. On flat ground 200W is about 20 MPH, 150W 18, and 100W 15. 1 kj out = 1 W * 1 sec = 1 kcal = 1 calorie in is a useful approximation; e,g, 100% of FTP. = 292 W, * 3600 w = 1051 calories.
