Why am I still so tired after 10 days on 20:4?

TIA for any help you can give me.

I’ve been on a 20:4 fast for 10 days, eating between 1200-1400 calories a day on a Mediterranean diet. I’m 65 years old, haven’t exercised in 20 years. I’ve lost a tiny bit of weight, I’d say probably only about 5 lbs, but I don’t own scales so I don’t weigh myself. I’m about 40 lbs. overweight.

I’m not consciously doing low carb, but I don’t eat a lot of carby foods either, mostly salmon, sardines, shrimp, fish with salad or veggies, occasional brown rice, a few eggs a week. I don’t eat sugar. I don’t eat fruit right now, because I’m avoiding carbs. I don’t have time to track my food, so I just mostly do serving sizes to track calories.

I’m doing this to lose belly fat because at my last doctor’s appt., he said I had fatty liver and was 3 points away from pre-diabetes. I knew I was eating way too much sugar, so I cut it out that day.

I don’t know why I’m still so fatigued. For one or two days, I had a sudden burst of energy, but paid for it the next day and haven’t really had much energy at all since then.

I do exercise, calisthenics with and without weights and also walk in place for at least 30 minutes a day. It’s just too danged hot to walk outside right now, but as soon as it cools down, I’ll be walking at least a mile or two a day.

What can I do to have more energy during the day? My eating window is 10 to 2 pm. Should I push it back some? I don’t want to have it in the evening, because I have night eating syndrome, where you don’t get hungry until after 7 at night, so I really want my stomach to be empty by 7. I could go 12 to 4, but I don’t see me pushing it any further than that. Does it really matter what time you eat?