Is physical weakness part of adjustment

Hi Brooke and team,
I am wondering if I am eating too little or is it just adjustment. For example. Yesterday I had black coffee in morning feeling weak, then tuna salad around noon. By 3pm I was so weak I could barely sit up in my chair. I had been drinking lots of water. I walked for about 30 minutes listening to your podcast hoping to shake it of. I did feel better but underlying weakness still there. I had raw vegetables and meatloaf for dinner. Still weak but not like before. I usually walk 4-5 miles 3 times a week. I don’t think I can do that now especially in heat. Or is it just mind set? In high school I developed an eating disorder trying to be very strict on “healthy” foods. I once passed out in my boyfriend’s living room. Feels the same to me. I wanted to be athletic and bike and hike but I had no energy. I want my body to burn fat for fuel. My husband does that beautifully. No dieting and always 2 meals a day no problem, not even hunger. I can deal with the hunger and cravings. But this weakness isn’t serving me. I will try eating more vegetables and more fat. Is this weakness typical with adjustment? If so I will guts it out. Any insight or advice?