Pros and Cons of High-Protein Diets
Experts look at the pros and cons of high-protein diets.
The Pros of High-Protein Plans
A big No. 1 on the list of pros for high protein is that it leaves a dieter feeling full and happy.
"Protein seems to leave the stomach slower than carb or fat, so a person may feel full longer with more protein in their diet," says Moores.
Fuller "longer" means that a dieter doesn't feel the need to eat as frequently, which can lead to weight loss. Appetite aside, high-protein diets encourage weight loss -- physiologically speaking.
"Weight loss occurs, often fairly quickly, which results in happy dieters -- short-term happy that is," Moores tells WebMD.
Why the short-term satisfaction? Because the weight loss is generally coming from the wrong place, and once the diet ends, the pounds come back.
"Much of the weight lost with the Atkins diet is water," says Karol Watson, MD, co-director of the UCLA Program in Preventive Cardiology.
Watson explains that eating only protein forces the body into starvation mode because most tissues, including the brain, typically prefer to run on glucose, or blood sugar, which is supplied by carbohydrates. On a carb-deprived, high-protein diet, trouble sets in.
"When there is not enough carbohydrate to convert into blood sugar, the body is forced to use stored blood sugar from the liver and muscles," Watson tells WebMD. "This process results in muscle breakdown. Because muscle is mostly water, one will lose weight very rapidly in the first few days. If the carbohydrate restriction is prolonged, the brain eventually will run on fat stores for fuel, called ketosis."
Unfortunately, ketosis brings with it more than weight loss, but a host of problems -- some serious.
"Ketosis is associated with irritability, headaches, and enhanced kidney work," says Johnston. "Also, ketosis may cause heart palpitations and has been implicated in cardiac arrest."
The effect of high-protein diets on the heart doesn't stop there -- the cardiovascular system comes into play as well.
"High-protein diets are often also high in saturated fat," says Watson. "Increased saturated fat intake raises the risk of coronary heart disease and stroke. In addition, some high-protein/low-carbohydrate diets limit intake of high-fiber plant foods, which can help lower cholesterol."
Overall, these diets might be power-packed in the protein department, but beyond that, they're lacking.
"High-protein diets lack critical nutrients," says Watson. "Restricting carbohydrates means you restrict plant-based foods, which are rich in phytochemicals and antioxidants. These chemicals offer protection against cancer and other diseases."
Keeping the Pounds Off
Another issue with protein-packed diets begins when the diet ends, and the pounds come marching in.
"It is often difficult to adhere to high-protein diets, and as soon as the diet ends, the weight is rapidly regained, leading to a potentially dangerous cycle of 'yo-yo dieting,'" says Watson.
High-protein diets can also impair kidney function in some individuals.