welcome back. I am wondering how thin you are now? In your photo you looked slim anyway and 40 lbs is a lot to loose. Unless you were overweight before, 40lbs would leave you very thin indeed. Maybe your mum is right?. Mums often know these things. My daughter lost a lot of weight 5 or so years ago due to depression and illness, and she looked awful, like one of those anoerexic sufferers. She has put about a 15 -20 lbs back on now, and looks just right, still slim but not skeletal.
As for your husband, cut out all sugar, sweets, potatoes, rice, pasta, cereals,cakes, most bread(and only eat wholmeal bread), chips, pastry, No white flour at all. I have lost 12lbs doing this, but am having to be very strict, and want to loose another 8 lbs. Its slow going, but if he has lot to loose he should loose it much faster.Also does he do exercise? A brisk walk every day is good.