1. Fats would need to be broken down into glycerol and fatty acids first. If fatty acids were to be respired they would first be degraded acetyl CoA and enter the pathway.
2. Glycerol would enter the pathway after being converted to phosphoglyceraldehyde.
3. The proteins would be degraded by proteases and the individual amino acids depending on their structure would enter the pathway at some stage within the krebs cycle or even as pyruvate or acetyl CoA.