My Body is Fighting Against Me

Male, 75 years old. About three months ago, I stepped onto a scale for the first time in about 3 years. I was aghast to see that I had gained 60 pounds, from about 185, my weight for the last 10 years, to 245. I noticed my gut swelling, but didn't pay it any heed because I had always lost weight easily in the past. This was a whole new experience. I cut my diet, but not drastically. Within about a week, I lost 10 pounds and was down to 235 or so. Easy-peasy, I thought. Boy, was I wrong. For the next two months or so, I vacillated between 235 and 240. I decided to try an all-protein diet. I got down to 230 and have not been able to drop below that, even by consuming 600-800 calories per day. The all-protein diet, even with a little vegetable, made me constipated, so I had to abandon all-protein and go back to my ordinary diet, which included a few half-cupfuls of lentils and wild rice. Here's a typical day's consumption: 3 soft boiled eggs at 6 AM and decaf with little sugar and cream small handful of walnuts 9 AM bare 3oz hamburger patty lean with slice tomato and mustard 11 AM couple spoonfuls of cottage cheese 4% fat before 2 PM nap bunless chicken sausage cut and stuffed with sauerkraut 5 PM 1/2 cup of spinach in a little broth 8 PM few spoonfuls of nonfat yogurt four times a day to wash down vitamins I cannot calculate more than about 700 calories in that diet. Yet I am up to 231 one day and then down to 230 the next. Sometimes I'm so hungry in the morning that I start to feel sick, and I have to wolf down a small slice of wheat bread (70 calories) to get some carbs into my system after 10 hours of not eating. My conclusion: It appears my body would rather send me into malnutrition before it gives up any pounds. Anyone else experiencing this?