Mike Mentzer and everyone said no nutrient make fat carbs or protein or fats, calories is what makes fat, so I think I can eat ice cream or anything I want If my calories are +300+500 calories above maintnace on lean bulk.
But then you get calories from eating nutrients. Carbohydrates require less energy (TEF) to digest, they also store as fat much easier that any other nutrient. Carbohydrates are converted into glucose, which are used for energy, and any extra glucose is stored in the liver and muscle as glycogen. After our glycogen storage is full extra energy is converted to adipose tissue. The shorter the carbon chain of the carbohydrate the easier/quicker it is to convert to glucose. So grape juice would quickly convert as compared to brown rice.
When fat is broken down into glycerol or odd carbon-chain fatty acids, it can be converted to glucose. So extra calories in fat are harder to convert into adipose. While it’s technically possible for some protein to be converted to fat, it’s not a major contributor to fat storage under normal circumstances. It i s also very energy costly for the body to digest and process protein.
Remember too ice cream is mile. Milk is full of lactose with is a simple sugar. It depends on your particular genetics, but for the most part simple carbohydrates should be limited.
Again, at your stage in the game, I would toss the lean bulk thing out the window and just eat. As long as you are training hard you are not going to put on very much fat at all and once you develop a solid base, then you can cut some of the fat off.