Basics

• Any protein-heavy diet emphasizes protein and fat intake while limiting carbs. Some diets, such as the Atkins, require followers to keep their carb intake to less than 20 g per day during the first two weeks (although the amount of carbs increases during on-going stages). Instead, followers of such a plan choose mostly protein-enriched foods such as eggs, lean meats, fish, poultry and low-starch vegetables. For instance, someone on a protein diet might have a cheese omelet with a side of sausage for breakfast, but no hash browns or a double cheeseburger with no bun for lunch.
  
  

Philosophy

• Supporters of protein plans say foods on their diet burn calories just by eating them, as the restriction on carbs switches the body from burning glucose to burning stored body fat. Protein is also considered the building block of muscle, which is why protein diets are often the choice of body builders. During initial phases, followers often experience headaches and a lack of energy as the body adapts. These side effects are later replaced by weight loss and improved vigor and mood, according to followers of these diets.
  
  

Pluses

• According to an extensive study published in the New England Journal of Medicine, if followed properly, a diet heavy in protein and low in carbs will indeed result in weight loss and increased energy. And while these diets do not allow you to consume unlimited amounts of protein and fat, they do allow you to eat plenty of your favorite foods without feeling hungry or deprived. Also, after the initial phases, most protein plans allow you to slowly incorporate some carbs back into your diet.
  
  

Minuses

• Since protein diets eliminate fruit and other high-fiber foods such as bread and pasta, followers can experience side effects like constipation or light-headedness (which is why it is critical for anyone on a protein diet to drink plenty of water and even take fiber supplements). Also, detractors question the long-term effects of diets that allow such high intakes of fat, particularly on the heart and kidneys. Besides that, protein diets severely limit food choices, making meat, fish or chicken the centerpiece of practically every meal.
  
  

Summary

• Protein diets can indeed have a short-term positive effect, especially when it comes to weight loss. Typically, people on protein diets lose most of their weight within the first two weeks (sometimes up to 10 or 15 lbs.). That slows during latter stages, as carbs are incorporated back into the diet. But like many "fad" diets, there is no evidence that protein diets are a healthy long-term solution.