Sincerely, Joshua M. Yelon
Vazquez JA, Adibi SA. Department of Medicine, Montefiore University Hospital, Pittsburgh, PA 15213.
Metabolism 1992 Apr;41(4):406-414
Although it is generally agreed that both ketogenic and nonketogenic very low calorie diets promote weight reduction, there is no consensus on a preference of one diet over the other in regard to protein sparing. In the present study, we compared the effects of isocaloric (600 kcal/d) and isonitrogenous (8 g nitrogen/d) ketogenic (low carbohydrate) and nonketogenic diets on parameters of protein and amino acid metabolism, in 16 morbidly obese women maintained on these diets for 4 weeks while confined to a metabolic ward. Cumulative urinary nitrogen excretion (g/4 wk) was significantly (P less than .01) greater (248 +/- 6 v 207 +/- 12, mean +/- SEM, n = 8), and cumulative nitrogen balance significantly (P less than .02) more negative (-50.4 +/- 4.4 v -18.8 +/- 5.7), during treatment with the ketogenic than with the nonketogenic diet. Plasma leucine concentration (mumol/L) was significantly higher (P less than .05) during treatment with the ketogenic than with the nonketogenic diet at day 14 (210 +/- 17 v 150 +/- 8), but not at day 28 (174 +/- 9 v 148 +/- 8). Whole-body rates of leucine oxidation (mmol/h) were significantly higher (P less than .05) during treatment with the ketogenic than with the nonketogenic diet at day 14 (1.29 +/- 0.20 v 0.92 +/- 0.10) and at day 28 (1.00 +/- 0.16 v 0.75 +/- 0.10). Conversely, proteolysis, as measured by leucine turnover rate and urinary excretion of 3-methylhistidine, was not significantly different between the diets.
Comments: they wanted to know: does a low-carb diet protect against muscle loss? So they got 16 women, and split them in two groups. Both groups got the same amount of calories (only 600, another starvation diet). Both got the same amount of protein. But, one group's diet included more fat, the other group's diet included more carbs. As it turns out, the low-carbers lost more muscle --- about 25% more. What they don't say is: how much fat did they lose? If the low-carbers lost 25% more fat, then the fact that they lost 25% more muscle would just mean they're losing weight 25% faster. There's no way to know from this abstract. If somebody could get a copy of the article and check on this, I'd appreciate it.
Walberg JL, Ruiz VK, Tarlton SL, Hinkle DE, Thye FW. Laboratory for Exercise, Sport, and Work Physiology, Virginia Tech, Blacksburg 24061.
Med Sci Sports Exerc 1988 Feb;20(1):34-43
Twelve obese women completed a maximal and an endurance exercise test (70% peak VO2) during a weight maintenance week. For the next 4 wk, the women consumed either a high (71%) carbohydrate (HC) or a low (33%) carbohydrate (LC), isonitrogenous very-low-calorie diet (VLCD) of 2,219 kJ (530 kcal).d-1. A supervised exercise session at 60% peak VO2 took place 3 times.wk-1 for 30 to 45 min. Peak VO2 and exercise endurance tests were repeated during the fourth week of the VLCD. One week of a 4,186 kJ (1000 kcal) diet followed the VLCD. The average weekly weight loss was 1.7 +/- 0.1 kg for the HC group and 2.0 +/- 0.2 kg for the LC group. Urinary nitrogen loss was greater for the LC group early in the VLCD but not different than HC over the entire experimental period. Serum cholesterol and high-density lipoprotein-cholesterol decreased in both groups but the ratio of these lipids improved over the treatment. Serum beta-hydroxybutyrate and uric acid increased significantly more for the LC than the HC group. Although absolute peak VO2 decreased, VO2 relative to body weight was maintained. Time to exhaustion improved by 36% for both groups in the endurance exercise tests. The endurance exercise R ratio was significantly more depressed by the LC than the HC treatment. In summary, both supervised treatments were effective in causing substantial weight reduction and improved blood lipid profiles in healthy young women but caused a net loss of body protein. Neither treatment compromised ability to participate in a thrice weekly exercise program. Although peak aerobic capacity did not increase, aerobic endurance at a fixed sub-maximal exercise load was improved.
Comments: 12 women were split into two groups (small sample size). Half received a low-carb diet, the other received a high-carb diet. This time, there really was a significant difference between the carb levels. Both diets were restricted to the point of near-starvation. They also made them exercise, and monitored the exercise so they exercised the same amount. The low-carb group lost more weight, but again, the difference was small. The low-carbers lost a little more muscle at first, but that trend negated itself later. The low-carbers had lower endurance as a group, both initially, and at the end. The exercise caused both groups to increase their endurance equally. Both groups improved their cholesterol and triglycerides.
Willi SM, Oexmann MJ, Wright NM, Collop NA, Key LL Jr. Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina. Record supplied by publisher.
Pediatrics 1998 Jan 1;101(1):61-67
Objective. To evaluate the efficacy and metabolic impact of a high-protein, low-carbohydrate, low-fat ketogenic diet (K diet) in the treatment of morbidly obese adolescents with initial weights of >200% of ideal body weight. Methods. Six adolescents, aged 12 to 15 years, weighing an average of 147.8 kg (range, 120.6-198.6 kg) and having an average body mass index of 50.9 kg/m (39.8-63.0 kg/m), consumed the K diet for 8 weeks. Daily intake consisted of 650 to 725 calories, which was substantively in the form of protein (80-100 g). The diet was very low in carbohydrates (25 g) and fat (25 g). This was followed by 12 weeks of the K diet plus two carbohydrates (30 g) per meal (K+2 diet). Main Outcome Measures. Anthropometric data and blood and urine were collected at enrollment, during week 1, and at 4-week intervals throughout the course of the study. Resting energy expenditure was measured by indirect calorimetry. Body composition was estimated using dual-energy x-ray absorptiometry, bioelectrical impedance analysis, and urinary creatinine excretion at enrollment and on completion of each phase of the diet. Nocturnal polysomnography and multiple sleep latency testing were conducted at baseline and repeated after an average weight loss of 18.7 kg to determine sleep architecture, frequency and duration of apneas, and daytime sleepiness. Results. Subjects lost 15.4 ± 1.4 kg (mean ± SEM) during the K diet and an additional 2.3 ± 2.9 kg during the K+2 diet. Body mass index decreased 5.6 ± 0.6 kg/m during the K diet and an additional 1.1 ± 1.1 kg/m during the K+2 diet. Body composition studies indicated that weight was lost equally from all areas of the body and was predominantly fat. Dual-energy x-ray absorptiometry showed a decrease from 51.1% ± 2.1% body fat to 44.2% ± 2.9% during the K diet and then to 41.6% ± 4.5% during the K+2 diet. Lean body mass was not significantly affected. Weight loss was accompanied by a reduction in resting energy expenditure of 5.2 ± 1.8 kcal/kg of fat-free mass per day. Blood chemistries remained normal throughout the study and included a decrease in serum cholesterol from 162 ± 12 to 121 ± 8 mg/dL in the initial 4 weeks of the K diet. An increase in calcium excretion was accompanied by a decrease in total-body bone mineral content. A paucity of rapid eye movement sleep and excessive slow-wave sleep were seen in all subjects at enrollment. Weight loss led to an increase in rapid eye movement sleep (P < .02) and a decrease in slow-wave sleep (P < .01) to near normal levels. Conclusions. The K diet can be used effectively for rapid weight loss in adolescents with morbid obesity. Loss in lean body mass is blunted, blood chemistries remain normal, and sleep abnormalities significantly decrease with weight loss.
Comments: They put some very heavy teenagers on a low-carb diet, but they only let them eat 700 calories a day. So they were practically starving. They lost a tremendous amount of weight: 18.7 kilos in a month and a half. They didn't lose muscle. Cholesterol levels improved. The diet fixed their sleep problems. On the downside, their bones lost calcium. This study isn't too useful, since it's more about the effects of starvation, than the effects of low-carb.