The effect of sucrase-isomaltase deficiency on metabolism, food intake and preferences: protocol for a dietary intervention study by Senftleber, NK, Skott Pedersen, K, Schnoor Jorgensen, C, Pedersen, H, Bjerg Christensen, MM, Kabel Madsen, E, Andersen, K, Jørsboe, E, Gillum, MP, Frost, MB, Hansen, T, Jorgensen, ME