In a 1999 study, a group of obese women were placed on a low-calorie diet. Some lost weight and some didn't. The ability to lose weight did not vary based on insulin resistance or high insulin levels in the blood. Eat more calories than your body burns and you'll gain weight. Eat fewer calories and you will lose weight.
Weight loss is simply a matter of arithmetic.
The high-protein content can reduce appetite. The low carbohydrate content can also cause fluid loss in the beginning, which shows up on the scales as weight loss. And, research shows just about any restrictive diet, the Hellers' included, is likely to result in weight loss. In short, people quit. Depending on the food choices you make, the diet may be high in saturated fat, which can raise blood cholesterol.