High-protein diets, such as the Atkins Diet and Zone Diet, restrict carbohydrate consumption. They work on the premise that the body must work harder to digest protein, so you burn more calories when you eliminate carbohydrates or minimize their consumption. While high-protein diets possibly cause fast weight loss, they may have unhealthy mental and physical side effects.
Ketosis
Your body uses carbohydrates for energy. When deprived of carbohydrates, your cells use fat as an energy source. This process creates molecules called ketones. Increasing the circulating ketones may cause an acid-base imbalance, warns the Physicians Committee for Responsible Medicine. Metabolizing proteins for energy also produces ammonia. Ammonia and ketosis both contribute to foul-smelling breath. While bad breath is not directly related to depression, it may cause social isolation, which could eventually lead to loneliness.
Mental Impairment
The ketosis associated with high-protein, low-carbohydrate diets may also impair mental functioning, reports R.R. Wing, lead author of a study published in the November 1995 "International Journal of Obesity and Metabolic Disorders." Wing's research team at the department of psychiatry, University of Pittsburgh School of Medicine, put two groups on low-calorie diets. Both diets contained the same amount of protein, but one diet, designated as a "ketogenic diet," contained no carbohydrates. The groups had similar weight-loss results, but subjects on the ketogenic diet performed poorly on the trail-making task, a neuropsychological test that requires advanced mental processing skills and mental flexibility.
Serotonin
Low-carbohydrate diets trigger a chain of chemical events in the brain, which reduce the absorption of the amino acid tryptophan into brain cells. This, in turn, decreases your levels of serotonin, a chemical that affects mood, reports Judith J. Wurtman, head of the Nutrition and Behavior Studies Group at Massachusetts Institute of Technology Clinical Research Center in Boston, and author of "The Serotonin Power Diet." Low serotonin levels cause depression, anxiety and irritability, which can create a craving for high-carbohydrate foods.
Additional Side Effects
In 2002, the Physicians Committee for Responsible Medicine created a registry that allowed people to report any adverse health conditions incurred while switching to a high-protein, low-carbohydrate diet. A total of 429 participants experienced health issues. Constipation, reduced energy levels, gastrointestinal problems, mood swings, nausea, high blood pressure and osteoporosis were among the reported illnesses and conditions. MayoClinic.com warns that some high-protein diets are also high cholesterol and may eventually cause heart disease and some types of cancers.
References
- Physicians Committee for Responsible Medicine; Analysis of Health Problems Associated with High-Protein, High-Fat, Carbohydrate-Restricted Diets Reported via an Online Registry; May 2004
- "International Jorunal of Obesity and Related Metabolic Disorders"; Cognitive Effects of Ketogenic Weight-Reducing Diets; R.R. Wing, et al.; November 1995
- "Journal of Affective Disorders"; Cognitive Function in Major Depression; M.P. Austin; May 1992;
- "The Serotonin Power Diet"; Judith Wurtman; December 2009
- MayoClinic.com: Low-carb Diet
- "The Telegraph"; Atkins-style Low Carb, High Protein Dieters More Likely to Suffer Depression; November 2009
