For anyone who has tried to lose weight or eat more healthily, Gary Taubes' book Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease will likely be revelatory reading (disclosure: I haven't read it yet). Taubes is a correspondent for Science magazine. He is also "the only print journalist to have won three Science in Society Journalism awards, given by the National Association of Science Writers, [and] he has contributed articles to The Best American Science Writing 2002 and The Best American Science and Nature Writing 2000 and 2003."
According to the publisher's website about the book, the following are the most significant conclusions of Taubes' investigation:
The 11 Critical Conclusions of Good Calories, Bad Calories:
1. Dietary fat, whether saturated or not, does not cause heart disease.
2. Carbohydrates do, because of their effect on the hormone insulin. The more easily-digestible and refined the carbohydrates and the more fructose they contain, the greater the effect on our health, weight, and well-being.
3. Sugars—sucrose (table sugar) and high fructose corn syrup specifically—are particularly harmful. The glucose in these sugars raises insulin levels; the fructose they contain overloads the liver.
4. Refined carbohydrates, starches, and sugars are also the most likely dietary causes of cancer, Alzheimer's Disease, and the other common chronic diseases of modern times.
5. Obesity is a disorder of excess fat accumulation, not overeating and not sedentary behavior.
6. Consuming excess calories does not cause us to grow fatter any more than it causes a child to grow taller.
7. Exercise does not make us lose excess fat; it makes us hungry.
8. We get fat because of an imbalance—a disequilibrium—in the hormonal regulation of fat tissue and fat metabolism. More fat is stored in the fat tissue than is mobilized and used for fuel. We become leaner when the hormonal regulation of the fat tissue reverses this imbalance.
9. Insulin is the primary regulator of fat storage. When insulin levels are elevated, we stockpile calories as fat. When insulin levels fall, we release fat from our fat tissue and burn it for fuel.
10. By stimulating insulin secretion, carbohydrates make us fat and ultimately cause obesity. By driving fat accumulation, carbohydrates also increase hunger and decrease the amount of energy we expend in metabolism and physical activity.
11. The fewer carbohydrates we eat, the leaner we will be.
Examples of good and bad calories are also described on this site. Here is the lowdown:
Good Calories
These are from foods without easily digestible carbohydrates and sugars. These foods can be eaten without restraint.Meat, fish, fowl, cheese, eggs, butter, and non-starchy vegetables.
Bad Calories
These are from foods that stimulate excessive insulin secretion and so make us fat and increase our risk of chronic disease—all refined and easily digestible carbohydrates and sugars. The key is not how much vitamins and minerals they contain, but how quickly they are digested. (So apple juice or even green vegetable juices are not necessarily any healthier than soda.)Bread and other baked goods, potatoes, yams, rice, pasta, cereal grains, corn, sugar (sucrose and high fructose corn syrup), ice cream, candy, soft drinks, fruit juices, bananas and other tropical fruits, and beer.
Needless to say, I'm sure this summary is not the complete picture, given its lack of the necessary qualifiers. So, read the book instead!
Update: Taubes' article questioning the relationship between exercise and fat loss is also worth reading. You can find it here.