A new study of the impact of adding eggs to the diet revealed some surprising results. It is known that obese, insulin-resistant people are more likely to have higher levels of “bad” choleserol in their blood and less “good” (HDL) cholesterol. Paradoxically, this new study showed that these same people are much less responsive to the cholesterol-raising effects of saturated fat and cholesterol from eggs than are normal subjects.1So why do obese people generally have more atherogenic cholesterol levels? It appears that insulin resistance itself promotes much of the adverse changes seen with weight gain and the metabolic syndrome. The impact on blood lipids of eating 4 eggs a day is significantly less in obese, insulin-resistant people than in people with normal insulin sensitivity. This may be why blood lipids often do not get much worse and even sometimes improve when obese, insulin-resistant people go on an Atkins-style diet and consume more cholesterol-rich foods such as eggs. However, weight loss itself usually improves insulin sensitivity. As weight is lost, this would likely restore the cholesterol-raising impact of eating more eggs. This may be why Dr. Flemming observed adverse changes in the blood lipids of obese subjects who lost 13.7% of their initial body weight by consuming an Atkins-style diet for one year. This would also help to explain why there was an alarming increase in “bad” cholesterol levels seen in Dr. Kwiterovich’s study of normal-weight children to a ketogenic diet high in saturated fat and cholesterol.By contrast, the far more modest changes observed in the blood lipids of obese adults in several studies when they adopt an Atkins-style diet may be due the fact that most were less responsive to the cholesterol-raising effects of eating more cholesterol-rich foods due to insulin resistance. Weight loss and a reduced calorie intake would tend to blunt the cholesterol-raising impact of a diet with a higher percentage of saturated fat and cholesterol.By James Kenney, PhD, RD, LD, FACN1. Arterioscler Thromb Vasc Biol 2003;23:1437-43.