One food diets work, if you choose your one food carefully, choose a food without carbohydrate, and limit your calories. My 4 favorite one food diets are steak, eggs, hot dogs and hamburgers. If you eat just steak, and limit yourself to 2 pounds a day, you can lose weight. A pound of steak is 800-1200 calories. Steak is 50-80 calories an ounce, depending on how fat or lean it is. If you eat just hot dogs (no buns), and limit yourself to a package a day, you can lose weight. A package of hot dogs usually is 800-1600 calories, and mustard is carbohydrate and calorie free. If you eat a dozen eggs a day, you can lose weight. Eggs are 80 calories each, so a dozen eggs are 960 calories. Add 400-800 calories for butter, and you’re at 1360-1760 calories a day, so you can lose weight. A fast food hamburger without the bun is 200 calories. You can eat 4-8 a day (800-1600 calories) and lose weight.