Moderately Low-Carb Diet Helps Insulin Resistance

LAS VEGAS — Dieting and losing weight will help patients with insulin resistance, but it should be a moderately low-carbohydrate diet, Dr. Tracey McLaughlin emphasized at the Fourth World Congress on the Insulin Resistance Syndrome.

That recommendation runs counter to those made by the American Heart Association and the American Diabetes Association, which recommend a diet that has less than 30% of calories consumed from fat. But the evidence bears it out, said Dr. McLaughlin, of the division of endocrinology at Stanford (Calif.) University. A diet a little lower in carbohydrates than in fat can result in equal weight loss, a better lipid profile, and lower insulin levels.

The lipid profile of someone with insulin resistance tends to be one with high triglycerides and low HDL cholesterol. In fact, a ratio of those two parameters is a good easy screen for insulin resistance—it should be 3.0 (or 1.8 in SI units), according to one study (Ann. Intern. Med. 2003;139:802–9). A diet higher in fat will improve both those parameters, she said. And a number of studies have suggested that a high carbohydrate diet for persons with insulin resistance can worsen those parameters.

Dr. McLaughlin performed one of the recent studies. She and her colleagues randomly assigned 57 obese, insulin-resistant individuals to either a diet of 60% carbohydrate, 25% fat, and 15% protein, or one of 40% carbohydrate, 45% fat, and 15% protein, for 16 weeks (Am. J. Clin. Nutr. 2006;84:813–21). One aim of the study was to use diets that were not too extreme in their restrictions on carbohydrate or fat because such diets, often effective in the short run, are difficult for individuals to sustain.

Average weight loss over the 16 weeks was slightly better in the higher fat diet, though not significantly so (6.9 kg vs. 5.7 kg). But the study found daylong insulin levels dropped an average 32% in those on the higher fat diet, compared with 13% in those on the higher carbohydrate diet. Daylong triacylglycerol dropped an average 25% with the higher fat diet, compared with 7% with the higher carbohydrate diet.

LDL cholesterol went up 12% in the subjects on the higher fat diet, and was unchanged in the subjects on the higher carbohydrate diet. However, the ratio of total cholesterol to HDL did not change in the subjects on the higher fat diet, which suggests that the lipid profile was not harmed by this increase in LDL, Dr. McLaughlin said. The study also found the more weight lost, the greater the improvement in insulin sensitivity.

LAS VEGAS — Dieting and losing weight will help patients with insulin resistance, but it should be a moderately low-carbohydrate diet, Dr. Tracey McLaughlin emphasized at the Fourth World Congress on the Insulin Resistance Syndrome.

That recommendation runs counter to those made by the American Heart Association and the American Diabetes Association, which recommend a diet that has less than 30% of calories consumed from fat. But the evidence bears it out, said Dr. McLaughlin, of the division of endocrinology at Stanford (Calif.) University. A diet a little lower in carbohydrates than in fat can result in equal weight loss, a better lipid profile, and lower insulin levels.

The lipid profile of someone with insulin resistance tends to be one with high triglycerides and low HDL cholesterol. In fact, a ratio of those two parameters is a good easy screen for insulin resistance—it should be 3.0 (or 1.8 in SI units), according to one study (Ann. Intern. Med. 2003;139:802–9). A diet higher in fat will improve both those parameters, she said. And a number of studies have suggested that a high carbohydrate diet for persons with insulin resistance can worsen those parameters.

Dr. McLaughlin performed one of the recent studies. She and her colleagues randomly assigned 57 obese, insulin-resistant individuals to either a diet of 60% carbohydrate, 25% fat, and 15% protein, or one of 40% carbohydrate, 45% fat, and 15% protein, for 16 weeks (Am. J. Clin. Nutr. 2006;84:813–21). One aim of the study was to use diets that were not too extreme in their restrictions on carbohydrate or fat because such diets, often effective in the short run, are difficult for individuals to sustain.

Average weight loss over the 16 weeks was slightly better in the higher fat diet, though not significantly so (6.9 kg vs. 5.7 kg). But the study found daylong insulin levels dropped an average 32% in those on the higher fat diet, compared with 13% in those on the higher carbohydrate diet. Daylong triacylglycerol dropped an average 25% with the higher fat diet, compared with 7% with the higher carbohydrate diet.

LDL cholesterol went up 12% in the subjects on the higher fat diet, and was unchanged in the subjects on the higher carbohydrate diet. However, the ratio of total cholesterol to HDL did not change in the subjects on the higher fat diet, which suggests that the lipid profile was not harmed by this increase in LDL, Dr. McLaughlin said. The study also found the more weight lost, the greater the improvement in insulin sensitivity.

LAS VEGAS — Dieting and losing weight will help patients with insulin resistance, but it should be a moderately low-carbohydrate diet, Dr. Tracey McLaughlin emphasized at the Fourth World Congress on the Insulin Resistance Syndrome.

That recommendation runs counter to those made by the American Heart Association and the American Diabetes Association, which recommend a diet that has less than 30% of calories consumed from fat. But the evidence bears it out, said Dr. McLaughlin, of the division of endocrinology at Stanford (Calif.) University. A diet a little lower in carbohydrates than in fat can result in equal weight loss, a better lipid profile, and lower insulin levels.

The lipid profile of someone with insulin resistance tends to be one with high triglycerides and low HDL cholesterol. In fact, a ratio of those two parameters is a good easy screen for insulin resistance—it should be 3.0 (or 1.8 in SI units), according to one study (Ann. Intern. Med. 2003;139:802–9). A diet higher in fat will improve both those parameters, she said. And a number of studies have suggested that a high carbohydrate diet for persons with insulin resistance can worsen those parameters.

Dr. McLaughlin performed one of the recent studies. She and her colleagues randomly assigned 57 obese, insulin-resistant individuals to either a diet of 60% carbohydrate, 25% fat, and 15% protein, or one of 40% carbohydrate, 45% fat, and 15% protein, for 16 weeks (Am. J. Clin. Nutr. 2006;84:813–21). One aim of the study was to use diets that were not too extreme in their restrictions on carbohydrate or fat because such diets, often effective in the short run, are difficult for individuals to sustain.

Average weight loss over the 16 weeks was slightly better in the higher fat diet, though not significantly so (6.9 kg vs. 5.7 kg). But the study found daylong insulin levels dropped an average 32% in those on the higher fat diet, compared with 13% in those on the higher carbohydrate diet. Daylong triacylglycerol dropped an average 25% with the higher fat diet, compared with 7% with the higher carbohydrate diet.

LDL cholesterol went up 12% in the subjects on the higher fat diet, and was unchanged in the subjects on the higher carbohydrate diet. However, the ratio of total cholesterol to HDL did not change in the subjects on the higher fat diet, which suggests that the lipid profile was not harmed by this increase in LDL, Dr. McLaughlin said. The study also found the more weight lost, the greater the improvement in insulin sensitivity.