Since this regulatory role of insulin in fat metabolism was established in the 1960s, a viable alternative explanation for the cause of obesity has been that it is caused by a dysregulation of insulin signaling. By this logic, the way to treat obesity is not by eating less and exercising more, as Ms. Parker-Pope implies, but by reducing insulin levels, perhaps as low as possible. That is accomplished most efficiently by severely restricting the carbohydrate content of the diet and removing, in particular, refined grains and sugars that have the greatest effect in stimulating insulin secretion.
The implication of this basic endocrinology is that obesity is caused not by eating too much and sedentary behavior, but by a disruption of the hormonal and enzymatic regulation of fat tissue caused by the easily digestible, refined carbohydrates and sugars that we do eat. Indeed, by this logic, calorie-restricted diets – starvation and semi-starvation diets as used in the studies Ms. Parker-Pope discusses – can be thought of as particularly counterproductive ways to reduce carbohydrate consumption and so insulin levels, starving the body, as they do, of the energy required to effectively run metabolic processes.
In the past decade, clinical trials have repeatedly demonstrated that when obese and overweight individuals consciously restrict the carbohydrates they eat, but not calories, they not only lose weight, on average, but their heart disease and diabetes risk factors improve significantly. Their insulin resistance, in effect, resolves. Those of us who have lost weight ourselves and witnessed the effect of these diets on our patients can confirm that this is exactly what happens.