For being one of the most nutrient-dense natural foods on the planet, eggs sure have taken a beating in the past few decades. The reason eggs have gotten such a bad rap is because they contain a fair amount of dietary cholesterol — about 185 mg per egg, almost all of which is housed in the yolk.
Decades ago, when the link between high cholesterol and cardiovascular disease was uncovered, medical experts advised limiting or completely avoiding the consumption of eggs (especially yolks), because dietary cholesterol could potentially raise blood cholesterol levels, therefore increasing the risk of heart problems.
With the passage of time and the publication of lots of new data, much of the negative hype about cholesterol in eggs and its effects on the heart has been refuted.
A strong body of research has shown that egg yolks have a much smaller effect on LDL (bad) cholesterol and triglycerides than originally thought, and actually boost HDL (good) cholesterol levels. In addition, large, long-term studies published in various reputable journals disproved any claims that eggs raised the risk of stroke and cardiovascular disease in healthy people.  
Furthermore, a seemingly small but very significant effect that eggs have on cholesterol has far-reaching implications. The consumption of eggs seems to change the pattern of LDL cholesterol in the blood from smaller, denser particles to larger, more buoyant forms. Smaller, denser particles are strongly associated with high LDL and triglycerides and low HDL, and are dangerous because they can squeeze between cells to reach the artery walls and cause blockages. So the larger the particles are, the better.
This finding was one of many factors that led researchers at the University of Connecticut to examine eggs’ role in improving cholesterol and insulin sensitivity in individuals with metabolic syndrome. In particular, they were curious to see how eggs affected atherogenic dyslipidemia, a strong factor associated with metabolic syndrome and heart disease. It is a condition that comprises a triad of increased blood concentrations of small, dense LDL particles, decreased HDL particles, and increased triglycerides.
Researchers followed 37 men and women aged 30–70 years who had metabolic syndrome for a 12-week period. The participants were given guidelines to follow a moderately carbohydrate-restricted diet for the entire 12 weeks (25 percent to 30 percent carbs, 25 percent to 30 percent protein, 45percent to 50 percent fat).
In addition, they were randomly divided into two groups. Researchers instructed the first group to consume three whole eggs per day, and the second group to consume the equivalent amount (about 1/2 cup) of yolk-free egg substitute (which is basically nutrient-fortified egg whites).
Each daily serving of whole eggs contained 534 mg of cholesterol, 0 g of carbohydrates, 16 g of protein, 12 g of fat and about 186 calories. In contrast, the daily serving of egg substitute contained about 2 g of carbohydrates, 14 g of protein and about 60 calories. (Note: The study authors did not mention how much cholesterol or fat was in the egg substitute. This is likely because most egg substitutes do not contain cholesterol or fat, or at least very minimal amounts since the yolk is removed.)
After 12 weeks, both groups experienced a 4 percent weight loss. But the main finding was that the combination of moderate carbohydrate restriction and whole egg intake improved atherogenic dyslipidemia and insulin resistance in the participants.
All the participants experienced decreased triglycerides and increased HDL cholesterol, as well as increased LDL particle size. However, those eating the whole eggs ended up with greater increases in HDL and LDL particle size, as well as larger reductions in total very-low density lipoproteins (VLDL), which contain the highest amount of triglycerides.
Researchers concluded that whole egg consumption, along with a moderately carbohydrate-restricted diet, provides improvements in lipid profiles and insulin resistance in individuals with metabolic syndrome.
Eat Those Eggs — Whole
Finally, whole eggs are truly getting the respect they deserve! All the attention surrounding cholesterol content has completely overshadowed the fact that eggs are nutritional powerhouses — with the majority of the nutrients residing in the yolk.
Ironically, egg yolks are a good source of heart-healthy omega-3 fatty acids (particularly DHA) and monounsaturated fats. And eggs as a whole, but especially the yolks, are a rich source of folate, vitamin A, selenium, potassium, calcium, choline, and the eye-protective carotenoids zeaxanthin and lutein. And, of course, as any bodybuilder will verify, eggs are a substantial source of muscle-building protein.
Simply put, for most people, there’s no reason to avoid whole eggs or to use egg substitutes. Now this recommendation rings exceptionally true for those who are dealing with metabolic syndrome. If you’re one of those people, feel good about enjoying eggs as nature intended — yolk and all.
 Weggemans RM et al. Dietary cholesterol from eggs increases the ratio of total cholesterol to high-density lipoprotein cholesterol in humans: a meta-analysis. Am J Clin Nutr. 2001 May;73(5):885–91.
 Hu FB et al. A prospective study of egg consumption and risk of cardiovascular disease in men and women. JAMA. 1999 Apr 21;281(15):1387-94.
 Qureshi AI et al. Regular egg consumption does not increase the risk of stroke and cardiovascular diseases. Med Sci Monit. 2007 Jan;13(1):CR1-8.
 McNamara DJ. The impact of egg limitations on coronary heart disease risk: do the numbers add up? J Am Coll Nutr. 2000 Oct;19(5Suppl):540S-48S.
 Fernandez ML. Dietary cholesterol provided by eggs and plasma lipoproteins in healthy populations. Curr Opin Clin Nutr Metab Care. 2006 Jan;9(1):8–12.
 Blesso CN et al. Whole egg consumption improves lipoprotein profiles and insulin sensitivity to a greater extent than yolk-free egg substitute in individuals with metabolic syndrome. Metabolism. 2012 Sep 26. http://dx.doi.org/10.1016/j.metabol.2012.08.014.