My preceding post got rather technical and delved into the finer points of cell biochemistry. For those who want to learn more about how cells work, I thoroughly recommend Metabolism at a Glance (Paperback) by Jack G Salway, Sen. Lecturer in Medical Biochemistry, University of Surrey. It's crammed with metabolic pathway diagrams.
I also recommend Medical Biochemistry at a Glance (Paperback) by Jack G Salway.
For general information on nutrition and metabolism, I recommend Introduction to Nutrition and Metabolism (Paperback) by David A Bender, Sen. Lecturer in Biochemistry, UCL.
A good site for information on fat loss, muscle gain etc is https://www.bodyrecomposition.com/.
A good site for nutrient data is https://nutritiondata.self.com/
A good site for peer-reviewed evidence is https://www.ncbi.nlm.nih.gov/pubmed/
A good site for searching textbooks is NCBI Bookshelf
A good site for clinical studies is https://clinicaltrials.gov/
A good site for enzyme structures is https://www.ebi.ac.uk/thornton-srv/databases/enzymes/.
Here's a searchable version of Biochemistry, by L Stryer.
It's a bit dry, but of interest is:-
Food Intake and Starvation Induce Metabolic Changes and
Phosphatidate Is a Common Intermediate in the Synthesis of Phospholipids and Triacylglycerols.
Here's a YouTube video of ATP Synthase, which takes a proton gradient and, using a molecular motor-generator, converts ADP + Phosphate into ATP, the energy source that cells use.
Happy reading and viewing!