Although there isn't one particular "protein and veggie" diet, low-carb diet plans emphasizing protein and vegetables while avoiding sugar and starch have been popular since the 1970s. Close to 32 million carb-conscious Americans spent $10 billion in the low-carb market in 2003, according to the market research firm Frost and Sullivan. Yet, studies investigating the health benefits and side effects of these diets have produced mixed results as to whether they're more helpful or harmful over the long term.
Identification
Most low-carb diets limit carbohydrate-rich foods such as potatoes, grains, pasta, bread and fruit to 50 g to 150 g daily and instead anchor their meal plans around protein sources such as meat, fish, dairy, eggs, nuts, beans and soy and non-starchy vegetables. Several of these diets rank foods according to a glycemic index, a measure of how quickly their sugars are released into your bloodstream, with carb-heavy foods at the high end and meats and green vegetables at the low end.
History
Research into ancient civilizations indicates that hunter-gatherer ancestors ate primarily protein, fat and low-carb vegetables. It wasn't until farming and industrial practices that humans began eating lots of sugar and carbohydrates, compounds implicated in a variety of health problems such as cancer and heart disease. In the 1860s, William Banting created the first modern low-carbohydrate diet, followed by Dr. Irwin Stillman in 1967 and Dr. Robert Atkins in 1972. By 2003, it was estimated by the professional food service company ARAMARK that 18 percent of Americans were limiting carbohydrates.
Effects
In principle, diets centered on protein and vegetables lower your insulin levels and allow your body to burn its stored fat for energy, resulting in weight loss. However, when your body burns fat instead of glucose for energy, it can lead to ketosis, or the development of compounds called ketones that can cause gout or organ failure in extreme cases. Some experts feel that the weight reduction from low-carb diets may just as likely be caused by other factors such as a decrease in calories, the diuretic effects of avoiding carbohydrates, and an increase in satiety since protein and fiber take longer to digest. (References 1, 3)
Expert Insight
One study that investigated the link between a low-carb diet and weight loss was led by
Gary Foster, PhD, director of Temple University's Center for Obesity Research and Education. His team followed 307 participants for two years, some of whom were on a low-fat diet and others who were on a low-carbohydrate diet with mostly protein and vegetables. The results, published in the "Annals of Internal Medicine" in August 2010, showed that the weight-loss results were about the same, 15 pounds or seven percent of body weight. However, the subjects on the low-carb diet had a potential added health benefit of a 23 percent increase in the levels of their good HDL cholesterol, as opposed to only 12 percent in the low-fat group. (References 5) Another study in the same journal, published one month later, used data from the decades-long Nurses' Health study to look at the types of low-carb diets. Teresa T. Fung, ScD, led the review that discovered a small but significantly higher mortality risk from a low-carb diet with more meat, versus a low-carb diet with a higher vegetable-to-meat ratio. Low-carb dieters who ate more protein and fat from animal sources like red and processed meats were 14 percent more likely to die of heart disease and 28 percent more likely to die of cancer. (References 4)
Considerations
In July 2003, Philippe O. Szapary, M.D., part of a University of Pennsylvania study comparing a low-carb diet to a conventional one, concluded that the best type of diet probably varies from one person to another and is determined by hereditary factors. He added that low-carb diets may be best suited if you have abnormally high triglyceride levels or have low HDL cholesterol levels. (References 3) It's also been shown that low-carb diets only work as long as you stay with them. Once you discontinue the diet, it's likely you'll regain any lost weight and possibly even more. (References 1)
Warning
Dr. Szapary cautions that low-carb diets are probably not wise if you have coronary artery disease, gout or kidney disease. If you do choose to undertake such a diet, you should consider having levels of blood lipids, creatinine, uric acid and glucose on a regular basis. The nutrition committee of the American Heart Association issued a science advisory warning stating such diets can include dehydration, and that a high-protein diet is risky if you have diabetes, because it may lead to diabetic kidney disease. (References 3)
References
- Mayo Clinic Online: Low-carb diet -- Could it help you lose weight?
- University of Maryland Medical Center: Low-Carb Diets: The Right Way to Go?
- Quackwatch: Low-Carbohydrate Diets
- "Annals of Internal Medicine": Low-Carbohydrate Diets and All-Cause and Cause-Specific Mortality; Teresa T. Fung, ScD, et al; September 2010
- "Annals of Internal Medicine" Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet; : Gary D. Foster, PhD et al; August 2010
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