The Paleo Diet - Loren Cordain [37]
Protein Satisfies Your Appetite
Protein’s high DIT is not the only reason you lose weight when you start eating more lean animal protein. Protein also affects your appetite. Protein satisfies hunger far more effectively than either carbohydrate or fat. Dr. Marisa Porrini’s research group at the University of Milan in Italy has found that high-protein meals are much more effective than high-fat meals in satisfying the appetite.
High-protein meats also do a much better job of reducing hunger between meals than do high-carbohydrate vegetarian meals. Dr. Britta Barkeling and colleagues at the Karolinska Hospital in Stockholm served twenty healthy women lunches of identical caloric value; the women ate either a high-protein meat casserole or a high-carbohydrate vegetarian casserole. The researchers then measured how much food the women ate at dinner. The women who had eaten the meat casserole ate 12 percent fewer calories during their evening meal. As this study illustrates, protein’s powerful capacity to satisfy hunger not only influences how much you eat at the very next meal but also how much you’ll eat all day long.
At the Rowett Research Institute in Great Britain, Dr. R. James Stubbs and colleagues fed six men a high-protein, high-fat, or high-carbohydrate meal at breakfast and then monitored their feeling of hunger for the next twenty-four hours. The high-protein breakfast suppressed hunger much more effectively than the other two breakfast meals did—even more than the high-fat breakfast. These experiments and many others have convincingly shown that if you want to feel less hungry and stay less hungry, lean animal protein is your best line of attack.
Theoretically, any leftover calories—whether they’re from protein, carbohydrates, or fats—would count as a calorie “surplus” and result in weight gain. In reality, the body doesn’t work that way. It is very difficult and inefficient for the body’s metabolic machinery to store excess protein calories as fat. The surplus almost always comes from extra fats or carbohydrates—and these are the foods that most frequently make you fat.
It is impossible to overeat pure protein. In fact, you couldn’t gain weight just on lean, low-fat protein if your life depended on it. The body has clear limits, determined by the liver’s inability to handle excess dietary nitrogen (released when the body breaks down protein). For most people, this limit is about 35 percent of your normal daily caloric intake. If you exceed this limit for a prolonged stretch of time, your body will protest—with nausea, diarrhea, abrupt weight loss, and other symptoms of protein toxicity.
But remember, protein is your best ally in waging the battle of the bulge—and when it is accompanied by plenty of fruits and veggies and good fats and oils, you will never have to worry about getting too much protein. Now let’s take a look at the next major reason why the Paleo Diet causes you to lose weight without nagging hunger.
Promoting Weight Loss by Improving Your Insulin Sensitivity
The Paleo Diet promotes weight loss not only because of its high protein level that simultaneously revs up your metabolism and reduces appetite, but also because it improves your insulin metabolism.
Insulin resistance is a serious problem, and most people who are overweight have it. In insulin resistance, the pancreas (the gland that makes insulin) must make extra insulin to clear blood sugar—glucose—from the bloodstream. There’s a bit of a “chicken and egg” argument as to which event happens first. Does being overweight cause insulin resistance or vice versa? Scientists aren’t