For overweight individuals known to secrete high levels of insulin, a diet low in sugar leads to greater weight loss than a diet high in sugar, investigators in Boston report. However, dietary sugar load or “glycemic load” makes no difference when insulin secretion is relatively low, according to the team.

These findings, the investigators note, “offer the first evidence that simple indexes of insulin secretion may help enhance weight loss success in overweight individuals through the use of targeted dietary recommendations specific for insulin secretion status.”

With insulin resistance, the body does not use the normal amount of insulin secreted by the pancreas properly, causing the pancreas to secrete more insulin.

Because both resistance to insulin and insulin secretion are involved in the regulation of body weight, Dr. Anastassios G. Pittas, from Tufts-New England Medical Center, and associates theorized that dietary glycemic (sugar) load could influence the effect of a diet designed to lose weight.

To test their theory, they assigned 32 healthy overweight adults to a high-glycemic load diet (glycemic load 116 g/1000 kcal) or a low-glycemic load diet (glycemic load 45 g/1000 kcal). Calories were restricted 30 percent compared with baseline individual energy needs for 6 months.

For those with high insulin secretion, the low glycemic load diet was associated with significantly greater weight loss than the alternative diet. Although the opposite pattern was observed among those with low insulin secretion, the results did not reach statistical significance.

The authors note that there are probably a number of mechanisms that could explain these results. High-glycemic load diets increase post-meal “hyperinsulinemia, which favors fatty acid uptake, inhibition of lipolysis, and energy storage leading to weight gain,” they note.

They also suggest that a high glycemic load may also increase hunger and thus increase eating during the postabsorptive period.

SOURCE: Diabetes Care December 2005.