When you're interested in losing weight, it's easy to become confused by the many popular diets available. One diet that's popular is a low-carbohydrate diet, also sometimes called a protein diet. These diets, however popular they are, challenge your body in multiple ways from a biochemical perspective and can be hazardous to your health and welfare.
Illusion of Weight Loss
One of the reasons that protein diets are so popular is that they often lead to dramatic, fast weight loss. If you're dieting, you probably want rapid results. As such, the 5 to 10 lbs. that dieters often lose in the first few weeks of a protein diet might tempt you to try one. Unfortunately, most of this early weight isn't fat weight -- it's water. According to Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry," when you deny your body carbohydrate, your brain pulls stored carbohydrate out of the liver and muscles for energy. This carbohydrate stores with lots of water, which is heavy. As you use the carbohydrate, you urinate out the water, leading to significant weight loss -- but it's water weight, rather than fat.
Weakness and Fatigue
Protein diets deny the brain and the muscles their preferred fuel -- glucose. The muscles use glucose and fat to produce movement, but hard efforts require large amounts of glucose, which you obtain from eating carbohydrate. The brain, too, needs glucose to function. A 2001 article in Obesity Research says that many protein dieters experience weakness and fatigue -- both mental and physical -- as a result of protein diets. This makes it hard to think, work and function, not to mention hard to work out. Since exercise is an important part of a healthy lifestyle, the inability of a protein dieter to maintain an exercise regimen can lead to a number of negative outcomes.
Ketosis
Protein diets force the body into a biochemical state called ketosis, says Dr. R.C. Kirby in a 2005 paper developed for the American Academy of Family Physicians. Because the brain's preferred fuel is glucose, when you deny your body carbohydrate, your brain begins to starve. Cells produce compounds called ketone bodies, which enter circulation and feed the brain. This allows your brain to continue to function, but it's a strong starvation signal, and your body responds to ketosis as a metabolic emergency. As a result, your cells start using less energy, meaning you need fewer calories to sustain your weight -- the result of which can be that it becomes harder to lose, and easier to gain, weight in the future.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Obesity Research"; Popular Diets: A Scientific Review; M. Freedman et al; 2001
- "Discussion Paper Developed for the AAFP Commission on Public Health"; Atkins Diet Discussion Paper; R.C. Kirby; 2005
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