The theory is that if the body doesn't have carbs to burn for energy, it goes into something called ketosis and burns fat instead, triggering weight loss. For breakfast, a mushroom and cheese omelette with a side of ham. Lunch could be a bacon cheeseburger from a fast food restaurant - hold the bun. For a snack, a handful of cheese cubes. And for dinner, shrimp cocktail with a mayonnaise and mustard sauce followed by a steak with a salad on the side.
People do lose weight over the first few weeks.
Although insulin definitely plays a role, the key is you're cutting calories. That's because under this plan, you typically get only about 1200 - 1500 calories a day. And when you cut calories, you lose weight. It's that simple. Although you may lose weight in the short-term, I have yet to see any studies that show how well it works in the long term.