Dr. Robert Lustig, Professor of Clinical Pediatrics at University of California San Francisco Center for Obesity Assessment, Study and Treatment, specializes in the role hormones play in weight and behavior. Through his published research, Lustig believes that sugar consumption promotes fat storage and weight gain through increased insulin production and is a factor in obesity. Although Lustig does not support a specific diet, he does make dietary recommendations based on his studies.
Background
Lustig first made the connection between insulin and obesity when he was observing children at St. Jude's Children's Research Hospital who became obese following brain tumor operations, a syndrome known as hypothalamic obesity. In this syndrome, damage to the hypothalamic brain area appears to promote excess food consumption and weight gain. Lustig believed that this damage caused leptin resistance. Leptin is a hormone that signals your brain that you have enough metabolic energy, which promotes a feeling of fullness and prevents overeating.
Leptin Resistance
Lustig theorized that leptin resistance triggers the brain to signal your pancreas for more insulin, a hormone involved in carbohydrate metabolism and fat storage. Lustig examined the effects of octreotide, an insulin-blocking drug, in a double-blind placebo-controlled study published in the June 2003 issue of "The Journal of Clinical Endocrinology and Metabolism." His study indicates that treating children suffering from hypothalamic obesity with octreotide resulted in significant weight loss and increased physical activity.
Elevated Insulin
Evidence published in the September 2005 issue of the "International Journal of Obesity," supports Lustig's suggestion that elevated insulin levels promote weight gain and obesity. He enrolled patients in this study who were at least moderately obese with evidence of elevated insulin secretion. These patients experienced significance weight loss after receiving a minimum of 40 milligrams of the insulin-blocking drug octreotide for six months.
Sugar Connection
Based on his research, Lustig recommends reducing your sugar consumption because sugar stimulates insulin production. The glycemic index is a numerical ranking system used to indicate how fast and how high a particular food can raise our blood glucose levels. Lustig recommends restricting high glycemic carbohydrates like candy, and focusing on healthy carbohydrate foods such as legumes, vegetables and whole grains. These types of carbohydrates digest slowly, triggering less insulin production. Lustig also recommends eating fruits because they are fiber-rich, which also slows sugar digestion. Lustig does not necessarily recommend a low-carb diet; he recommends choosing healthy carbohydrates that will not create a surge in insulin levels.
Fructose
Nationwide fructose consumption has been linked to obesity and diabetes, according to Lustig in his book "Obesity Before Birth." Lustig recommends eliminating fructose, a common sweetener. Although his research is ongoing, he believes that the fructose added to food and beverages causes a more dramatic increase in insulin than other types of sugars. There is a small amount of fructose found naturally in fruits and vegetables, which is not considered harmful. Lustig recommends eliminating sugar-sweetened beverages as well.
References
- The Journal of Clinical Endocrinology and Metabolism: Octreotide Therapy of Pediatric Hypothalamic Obesity: a Double-blind, Placebo-controlled Trial
- International Journal of Obesity: A Multicenter, Randomized, Double-blind, Placebo-controlled, Dose-finding Trial of a Long-acting Formulation of Octreotide in Promoting Weight Loss in Obese Adults with Insulin Hypersecretion
- Nutrition and Metabolism: Dietary Carbohydrate Restriction in Type 2 Diabetes Mellitus and Metabolic Syndrome: Time for a Critical Appraisal
- Obesity Before Birth: Maternal and Prenatal Influences on the Offspring; Robert H. Lustig; September 2010
- Pituitary Network Association: Hypothalamic Obesity
