I am reducing fat for a month doing gym and spinning, and now I'd want to add cycling to it. On spinning days I've been eating like in non-training days, about 2100kcal. But it lasted 1,5h max, what about long 5h cycling session days? How much should I increase my calories intake? What should I eat?
1Can you elaborate more on the nature of the 5 hour rides? Fuelling requirements for slow endurance session on the flat are totally different to riding a brisk pace on hilly terrain.– Andy PMar 15, 2016 at 11:11
Flat terrain, road bike, slow endurance session - about 25km/h avg.– khernikMar 15, 2016 at 11:11
Understand that you need to get carbs, not fat or protein. And, at least until your body "learns" to store more carb-like stuff in the liver and muscles, you need to snack during the ride.– Daniel R HicksMar 15, 2016 at 12:30
Well to start with, you don't just leap from 1.5hr spin sessions to 5 hour rides - unless you have a long history of cycling this would most likely not end well.
However, to answer the nutrition question:
While you are riding, there is a limit to how many calories you can absorb. Most sources will quote 60-75g of carbohydrate per hour (240-300kcal per hour). You will want to choose an energy source that is mostly carbohydrate, although a small amount of protein can protect muscle mass and improve recovery.
Over a 5 hour ride this will add up to in the region of 1200-1500 extra calories, which may seem a lot, but will still be less than you are burning.
As you become more experienced with this type of ride, your body will adapt to use fat as its primary fuel source and you will find you are able to gradually reduce your energy intake should you wish to do so.
1You may also look at when you are consuming different types of calories and adjust accordingly. Caloric debt is caloric debt and you will lose weight that way, however, you can make things easier on yourself by consuming the right foods at the right times. Mar 15, 2016 at 17:05
1While not explicitly requested by the OP, I just wanted to bring up the importance of fluid intake on long rides. Without adequate hydration the body cannot make use of the consumed calories. Many underestimate hydration needs (drinking too little too late) making keeping on top of hydration can be difficult for most riders new to distance riding.– Rider_XMar 15, 2016 at 23:38