Yes, it’s pretty normal. Your healing & recovering from a pretty major surgery & feeling tired is yiur body telling you to rest to allow it to heal. Plus you’ve made considerable changes to your diet which takes a bit of getting used to as well. If you feel tired, rest. Don’t push yourself to do more. It does get better though you may still experience periods of tiredness at times. Try an electrolyte drink (I used hydralyte) to give you a little boost of energy on days when you have a few chores to do. Take some with you when you’re out or stop at a cafe and rest over a cup of tea. I did this often.