From Dr. John McDougall- Sickening Foods:
The foods recommended for a high protein diet are mainly meat, eggs, and dairy products, which are high in cholesterol, fat, and animal protein; and deficient in dietary fiber, carbohydrate; and are often highly contaminated with chemicals and microbes; and have serious vitamin and mineral imbalances.
"Nutrition and Health in the United States," published under the direction of Surgeon General C. Everett Koop MD in 1988 put to rest all controversy concerning whether or not diet is fundamental in the cause, prevention, and treatment of common diseases. "The Report's main conclusion is that overconsumption of certain dietary components is now a major concern for Americans. While many foods are involved, chief among them is the disproportionate consumption of foods high in fats, often at the expense of foods high in complex carbohydrates and fiber that may be more conducive to health." Similar recommendations to eat fewer animal products and more plants foods have been made by every other health organization, including the Senate Select Committee on Nutrition, American Heart Association, the American Cancer Society, The Diabetic Association, and the American Dietetic Association. They all believe, to one degree or another, that the chronic illnesses plaguing modern Western society are caused by an unhealthy diet and lifestyle, and that improved health comes from eating fewer animal products and a more plant food-based diet.
The diseases believed to be caused by meats, eggs, and dairy products include most cases of: obesity, heart diseases, adult diabetes, breast, colon, and prostate cancer, gallbladder disease, osteoporosis, kidney failure, kidney stones, multiple sclerosis, rheumatoid arthritis, constipation, diverticulosis, hemorrhoids, and hiatal hernia to name a few well studied diseases. You don't have to be a trained nutritionist to see the risk of becoming sick increases the more of these unhealthy foods that are eaten--like with high-protein diets.