Eating well is the first defence. If appetite is low, try soups, protein shakes, smoothies - prioritise protein and fruits and veg. I lost muscle through the MLC diet and still rebuilding now. Any weight lost will not just be fat.
Rest, rest, rest. I still need more sleep than prior MLC, though getting back to normal. If you're tired, rest. Delegate, prioritise. Don't be a hero, ask for help! If people offer, take them up on it. Often people do want to help but don't know what would be of most benefit to you. And yet we don't ask. Exhaustion is your body's way of saying stop, you're working too hard. Simplify your life where possible.
5htp is my go to supplement for sleep. Magnesium and vitamin D are important. I meditate, do yoga, and walk daily with the dog, usually in a park or nature reserve. I also don't watch much telly, especially not the news. I love myself and prioritise what makes me happy and healthy.