In 1977 and 1983, National dietary guidelines were introduced by the US and UK governments, advising us to reduce the intake of saturated fat and promoted a high carbohydrate diet in an attempt to reduce heart disease. Interestingly enough, the obesity epidemic in the United States started at almost the exact same time the low-fat guidelines first came out.
Recent reviews of all the research on saturated fat published in the American Journal of Clinical Nutrition found there was no correlation between saturated fat and heart disease. Researchers have found that, while it’s true that lowering saturated fat in the diet may lower total cholesterol, it’s actually lowering the good kind of cholesterol, LDL that’s not the problem. Additionally, the low-fat, high carbohydrate theory promoted the overeating of carbohydrates which prevent a higher percentage of fats from being used for energy, and lead to an increase in fat production and storage. It also raises your insulin levels, which in short order can cause insulin resistance, followed by diabetes and linked to a variety of chronic ailments
Your body has a limited capacity to store excess carbohydrates. This is one of the reasons why elevated blood sugar follows their overconsumption. One of the ways your body avoids dangerously elevated blood sugar is through converting those excess carbohydrates into excess body fat primarily in your belly. The way it works is that any carbohydrates not immediately used by your body are stored in the form of glycogen. Your body has two storage sites for glycogen: your liver and your muscles. Once the glycogen levels are filled in both your liver and muscles, excess carbohydrates are converted into fat and stored in your adipose, that is, fatty, tissue. Even “fat-free” carbohydrates follow the same mechanism
To make matters worse, any meal or snack high in carbohydrates will also generate a rapid rise in blood glucose. To adjust for this rapid rise, your pancreas secretes insulin into your bloodstream, which then lowers your levels of blood glucose. The problem is that insulin is essentially a storage hormone, evolved to put aside excess carbohydrate calories in the form of fat. In other words, when you eat too much sugar, bread, pasta, and any other grain products, you're essentially sending a hormonal message, via insulin, to your body that says "store more fat”. For nearly everyone reading this, having insufficient calories is not an issue, so this protective mechanism actually sabotages your health. Conversely, eating fat makes you fuller sooner and longer. Eating sugar/carbohydrates leads to a sugar crash which makes you hungrier sooner and in a position to crave more sugar
According to Paul Jaminet, PhD. in his book Perfect Health Diet, a 20 percent carb diet is healthy for nearly everyone. He also believes that 50-70 percent of your diet should be healthy fat (healthy fats include not only monounsaturated fats like olive oil but also saturated fats, like those found in raw dairy products and grass-fed meat). Adequate protein intake is also necessary for a healthy balanced diet as well as avoiding transfats/fried foods which are both high in unhealthy fat as well as refined carbohydrates.
So what kind of fats should you be eating?
Olives and olive oil
Raw nuts such as almonds, walnuts or pecans
Grass fed meats
Coconuts and coconut oils
Eggs with the yolks