Struggling with less fat/protein

Advice wanted. I’m trying to go fat free until lunch but I’m finding it really difficult. I start my day with LW and then CJ and I’m eating steamed potatoes 400g worth , carrots, peas, green beans etc for breakfast and a banana and an apple a little later. I’m finding myself going into an almost comatose state with extreme fatigue, tingling fingers, blurry vision and brain fog after eating that slowly improves about 2 hours later. I’m currently significantly underweight and suffering circulation issues, hair loss and weakness due to that. I’m coming into MM after trying an almost ketogenic diet very high in animal products and fat to try and solve my chronic fatigue and SIBO. Now as soon as I eat protein or fat at lunchtime it’s like my body finally feels balanced again and my energy stabilises. Is this reaction normal? I truly don’t think I can handle fat free mornings anymore as the crashes are so severe I can’t function. What should I do? I also can’t ignore my low weight and I feel as though I’m going to lose if I keep eating like this. Should i maybe try to stabilise my weight first and then approach MM properly? Thanks in advance