4. Discussion of Health Concerns
Extract from "Updated Analysis of Health Problems Associated with High-Protein, High-Fat, Carbohydrate-Restricted Diets Reported via an Online Registry" by the Physicians Committee for Responsible Medicine (PCRM) (Dec, 2003)
Note: Numbers in brackets refer to research references. See Low Carb Eating References
Constipation
Constipation was reported by 44 percent of the registrants. One registrant reported severe problems with constipation: “I frequently resorted to laxatives and sometimes went two weeks without a bowel movement.” In one study, 68 percent of subjects on a low-carbohydrate diet reported problems with constipation. (1)
Carbohydrate-rich plant foods, including vegetables, fruits, grains, and legumes, are the main sources of fiber in the diet. High-protein, carbohydrate-restricted diets are typically low in fiber, and, as a result, often lead to constipation. In our nutrient analysis of the sample menus in Dr. Atkins’ New Diet Revolution, fiber content ranged from two grams per day on the Induction Diet to 18 grams per day on the Maintenance Diet. The new Institute of Medicine recommendations target fiber intake at 14 grams per 1000 kcals, which works out to 28 to 42 grams per day for an average adult. Individuals consuming Atkins-like diets generally fall far short of this healthy goal.
Lack of Energy
Loss of energy was reported by 40 percent of registrants. One registrant noted feeling “exhausted, dizzy, and nauseated before almost passing out on the 5th day of the diet.” Another noted being “so weak I can hardly function.” A third stated, “After two weeks I felt terribly tired and ended the diet with a donut binge session.” Loss of energy would be expected on a carbohydrate-restricted diet, because the preferred fuel for the body is carbohydrate in the circulating form of glucose or the storage form of glycogen. Muscles need glucose to do maximal effort work. (19) Limiting carbohydrate intake requires the body to utilize other fuels, such as fats, amino acids, and ketone bodies. Conversion of these nutrients to useable fuels takes longer than providing glucose from carbohydrates. For brain function and high-intensity activities, these fuels are poor substitutes for glucose. In addition, during the induction and maintenance phases, recommended caloric intake (1500–1700 kcals) is well below adult energy requirements.
Bad Breath (Halitosis)
Bad breath was reported by 40 percent of the registrants. One registrant noted, “I was miserable on this diet. I had no appetite, no energy, and a terrible taste in my mouth all the time.” A second summed up her statement with, “Bad breath, funny taste in mouth, feeling lethargic...and this diet is good for you? My body didn't think so!”
Bad breath occurs on high-protein, carbohydrate-restricted diets, especially during the induction and weight-loss phases, when a ketotic state is achieved. Problems with bad breath were reported in 63 percent of patients on such diets in a study done at Duke University. (1) When fatty acids are the primary source of energy and carbohydrate is severely restricted, part of the fat particle cannot be metabolized and builds up in the fluids outside the cells. These particles are converted to ketones (an “emergency” energy source), and unused ketones are excreted in the urine and expired air, resulting in acetone-smelling breath. (16)
Lack of Concentration
Difficulty concentrating was reported by 29 percent of the registrants. One registrant described her experience this way: “I felt horrible. I couldn’t concentrate or focus and felt foggy all the time.” Another stated, “I was only on the diet a short time and had a vertigo attack. I have since been out of balance and have a loss of concentration.”
The primary fuel for the brain and nervous system is carbohydrate in the form of glucose. When carbohydrate or total food intake is restricted (especially when such restriction is <40 g/day), there is little or no glucose available for the brain. The brain cells can utilize ketone bodies for energy in an emergency, such as starvation or severe carbohydrate restriction, (20) but some individuals can still note the deficiency of glucose available to the brain. Possible symptoms include difficulty concentrating or light-headedness.
INDEX to PCRM Low Carb Health Problems Report
-----------------------------------------------------------------------
The PCRM Report:
- Introduction and Methods
- Findings
- Nutrient Analysis
- Discussion
of Health Concerns
- Constipation
- Lack of Energy
- Bad Breath
- Lack of Concentration
- Kidney Problems (and Gout)
- Heart Disease
- Gall Bladder Problems
- Diabetes
- Cancer
- Limitations of Weight Loss - References
- Appendix: Diet Menus Used for Nutrition Analysis
