I would like to start a thread to examine the calorie balance "hypothesis." I hope to include only studies that were tightly controlled, as evidence has shown that self-reported intake is highly inaccurate, even in trained individuals (I also hope to start a thread discussing this). Therefore, I wish to completely avoid studies that use self-reported data.
I expect that the majority of these studies will come form closely monitored metabolic wards, and I'd also like to include some that utilized doubly labeled water, as these seem some of the most reliable studies as far as actual intake is concerned. As these studies are very expensive, I will not be surprised if there are not many available. However, I feel that the data they contain may be significantly more valuable than studies that utilize self-reported data.
The major point I wish to examine will be net calorie balance vs weight (ie, the calorie balance "hypothesis"). However, bonus points will be awarded for studies that meet the above criteria and also compare *isonitrogenous* low and high carbohydrate diets, especially if body composition (and not just weight) is analyzed.
Just because this is interesting:
<div class='quotetop'>QUOTE </div><div class='quotemain'>Am J Clin Nutr. 1995 Oct;62(4):735-9. Links
Energy metabolism in weight-stable postobese individuals.
Larson DE, Ferraro RT, Robertson DS, Ravussin E.
Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ, USA.
A low metabolic rate for a given body size and body composition and a low ratio of fat to carbohydrate oxidation predict body weight gain. Such metabolic traits could also explain, in part, the propensity of previously obese (postobese) individuals to regain weight after dieting. We studied 11 postobese volunteers (4 males, 7 females; aged 43 +/- 13 y, weighing 80.6 +/- 10.2 kg, with 30 +/- 7% body fat; x +/- SD) who lost 57 +/- 38 kg (23-139 kg) over 14 +/- 12 mo (6-48 mo) on various diet programs and had maintained this weight loss for > or = 2 mo (2-72 mo; 21 +/- 27 mo). After > or = 2 d of a weight-maintenance diet on a metabolic ward, 24-h energy expenditure and ratio of fat to carbohydrate oxidation were measured in a respiratory chamber. Compared with a control group (n = 110) with similar physical characteristics (aged 43 +/- 14 y, weighing 79.5 +/- 11.4 kg, with 30 +/- 12% body fat), [sequence: see text] postobese individuals had similar energy expenditures adjusted for fat-free mass, fat mass, age, and sex, but significantly higher respiratory quotients over 24 h (0.883 +/- 0.026 compared with 0.863 +/- 0.024, P < 0.01) and during sleep, 10 h after the last meal (0.894 +/- 0.063 compared with 0.845 +/- 0.055). These results suggest that postobese individuals have low rates of fat oxidation that may explain their propensity to regain weight.(ABSTRACT TRUNCATED AT 250 WORDS)
PMID: 7572701 [PubMed - indexed for MEDLINE]</div>
This one (FFT) might be interesting discussion -- less than half the carbs, but an appropriate weight loss: deficit ratio (whereas a low CHO enthusiast might expect a significant weight loss: deficit ratio for the lower CHO diet).
<div class='quotetop'>QUOTE </div><div class='quotemain'>Am J Clin Nutr. 1992 Oct;56(4):636-40. Links
Body composition, nitrogen metabolism, and energy utilization with feeding of mildly restricted (4.2 MJ/d) and severely restricted (2.1 MJ/d) isonitrogenous diets.
Stanko RT, Tietze DL, Arch JE.
Clinical Nutrition Unit, Montefiore University Hospital, Pittsburgh, PA 15213.
To determine the effects on weight loss of feeding isonitrogenous diets in mildly restricted (4.2 MJ/d) and severely restricted (2.1 MJ/d) amounts, we measured body composition, weight loss-energy deficit ratio, and nitrogen metabolism in 14 obese women housed in a metabolic ward consuming hypoenergetic diets for 21 d. Subjects consumed either a 4.2-MJ/d diet (50 g protein, 175 g carbohydrate) or a 2.1-MJ/d diet (50 g protein, 75 g carbohydrate). Body composition and leucine oxidation and turnover were determined before and after weight loss. Energy deficit was calculated from resting metabolic rates. Subjects fed the 2.1-MJ/d diet showed a greater weight loss (6.1 +/- 0.5 vs 4.5 +/- 0.5 kg; mean +/- SE, P less than 0.05) and fat loss (3.9 +/- 0.3 vs 3.0 +/- 0.3 kg, P less than 0.05). Weight loss-energy deficit ratio was the same with both diets. Nitrogen balance and leucine oxidation and turnover were similar in both groups. We conclude that with feeding of isonitrogenous hypoenergetic diets, severe restriction of energy content (2.1 MJ/d, 75 g carbohydrate) will enhance weight and fat loss without increasing nitrogen loss compared with mild restriction of energy (4.2 MJ/d).
PMID: 1414962 [PubMed - indexed for MEDLINE]</div>
I don't know what to make of this one, as it involves a supplement outside of normal dietary intake (FFT):
<div class='quotetop'>QUOTE </div><div class='quotemain'>Am J Clin Nutr. 1992 Oct;56(4):630-5. Links
Body composition, energy utilization, and nitrogen metabolism with a 4.25-MJ/d low-energy diet supplemented with pyruvate.
Stanko RT, Tietze DL, Arch JE.
Clinical Nutrition Unit, Montefiore University Hospital, Pittsburgh, PA 15213.
We measured body composition, energy deficit, and nitrogen metabolism in 14 obese women housed in a metabolic ward, who consumed a 4.25-MJ/d liquid diet (68% carbohydrate, 22% protein) for 21 d with or without pyruvate (PY; n = 7) partially, isoenergetically substituted for glucose (placebo; n = 7). Body composition and leucine oxidation and turnover were determined before and after weight loss. Energy deficit was calculated from resting metabolic rates. Subjects fed pyruvate showed a greater weight loss (PY = 5.9 +/- 0.7 kg, placebo = 4.3 +/- 0.3 kg, P less than 0.05), fat loss (PY = 4.0 +/- 0.5 kg, placebo = 2.7 +/- 0.2 kg, P less than 0.05), kg wt loss/4.25-MJ deficit (PY = 0.22 +/- 0.01 kg, placebo = 0.17 +/- 0.01 kg, P less than 0.05, and kg fat loss/4.25-MJ deficit (PY = 0.15 +/- 0.01 kg, placebo = 0.11 +/- 0.01 kg, P less than 0.05). Nitrogen balance (urine and stool) and leucine oxidation and turnover were similar in both groups. We conclude that the dietary modification whereby the three-carbon compound pyruvate is isoenergetically substituted for the six-carbon compound glucose in a 4.25-MJ/d, low-energy diet will increase fat and weight loss.
PMID: 1414961 [PubMed - indexed for MEDLINE]</div>
I'll have to see if I can't get the FT on this one to see if weight loss was measured:
<div class='quotetop'>QUOTE </div><div class='quotemain'>Metabolism. 1992 Apr;41(4):406-14. Links
Protein sparing during treatment of obesity: ketogenic versus nonketogenic very low calorie diet.
Vazquez JA, Adibi SA.
Department of Medicine, Montefiore University Hospital, Pittsburgh, PA 15213.
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.(ABSTRACT TRUNCATED AT 250 WORDS)
PMID: 1556948 [PubMed - indexed for MEDLINE]</div>
Possibly due to high bodily stores of energy reserves?
<div class='quotetop'>QUOTE </div><div class='quotemain'>Am J Clin Nutr. 1989 Jul;50(1):41-5. Links
Weight loss in 108 obese women on a diet supplying 800 kcal/d for 21 d.
Webster JD, Garrow JS.
Nutrition Research Group, Clinical Research Centre, Harrow, UK.
A series of 108 obese women were studied for 21 d in a metabolic ward on a diet supplying 800 kcal/d (3.4 MJ/d), with 4.5 g protein nitrogen, 40% energy from fat, and 46% from carbohydrate. The average total weight loss was 5.0 kg. During the second and third week on the diet the rate of weight loss was 211 +/- 77 g/d (mean +/- SD) and individual values were well predicted by admission resting metabolic rate (RMR) (r = 0.66, p less than 0.0001). The calculated energy density of the weight lost in this phase was 7000 kcal/kg (29.3 MJ/kg). However, the weight loss in the first week had a labile component of 815 +/- 1202 g, which was not well predicted by RMR (r = 0.20, p less than 0.05). The effect of this labile component was to obscure the overall rate of weight loss so some of the patients did not show net weight loss until day 13 of the diet, although they were in negative energy balance.
PMID: 2750694 [PubMed - indexed for MEDLINE]</div>
<div class='quotetop'>QUOTE </div><div class='quotemain'>Lancet. 1989 Jun 24;1(8652):1429-31.Links
Effects on weight and metabolic rate of obese women of a 3.4 MJ (800 kcal) diet.
Garrow JS, Webster JD.
Rank Department of Human Nutrition, St Bartholomew's Hospital Medical College, London.
103 obese women (mean [SD] Quetelet's index [weight/height2] 38  kg/m2) were admitted to a metabolic ward and were kept strictly to a diet providing 3.4 MJ (800 kcal) daily for 3 weeks. Body weight was measured daily and fasting resting metabolic rate (RMR) on days 1, 7, and 21. Both weight and RMR fell more rapidly in the first week than later. The thermic effect of feeding fell immediately on the lower energy intake, and there was an adaptive reduction of about 6% in RMR in week 1. After 3 weeks, the average weight loss was 4.9 (1.2) kg (about 5% of initial weight) and the average fall in RMR 8.8%. If after substantial weight loss a woman eats just enough to maintain energy balance the adaptive reduction in metabolic rate is restored to normal, and the thermic effect of feeding is restored in proportion to the new energy intake, but total energy requirements remain less than in the obese state to the extent that fat-free mass has been reduced. Thus, an obese woman who reduces weight by 30% over a year will thereafter have requirements for weight maintenance which are reduced by about 15%.
PMID: 2567437 [PubMed - indexed for MEDLINE]</div>
<div class='quotetop'>QUOTE </div><div class='quotemain'>Am J Clin Nutr. 1987 Oct;46(4):622-30. Links
Effects of exercise and food restriction on body composition and metabolic rate in obese women.
Hill JO, Sparling PB, Shields TW, Heller PA.
Clinical Nutrition Research Unit, Vanderbilt University School of Medicine, Nashville, TN 37232.
Obese women (140-180% of ideal body weight) were studied on a metabolic ward during 1 wk of maintenance feeding, followed by 5 wk of 800 kcal/d (liquid formula diet). Five subjects participated in a supervised program of daily aerobic exercise and three subjects remained sedentary. Total weight loss was not different between exercising and nonexercising subjects but significantly more of the weight loss came from fat and less from fat-free mass in the exercising subjects. Resting metabolic rate (RMR) declined similarly in both groups (approximately 20%), even though exercising subjects were in greater negative energy balance due to the added energy cost of exercise. In summary, results from this controlled inpatient study indicate that exercise is beneficial when coupled with food restriction because it favors loss of body fat and preserves fat-free mass.
PMID: 3661479 [PubMed - indexed for MEDLINE]</div>
<div class='quotetop'>QUOTE </div><div class='quotemain'>Diabetes. 1986 Feb;35(2):155-64.Links
Metabolic consequences of very-low-calorie diet therapy in obese non-insulin-dependent diabetic and nondiabetic subjects.
Henry RR, Wiest-Kent TA, Scheaffer L, Kolterman OG, Olefsky JM.
To determine the effects of very-low-calorie diets on the metabolic abnormalities of diabetes and obesity, we have studied 10 obese, non-insulin-dependent diabetic (NIDDM) and 5 obese, nondiabetic subjects for 36 days on a metabolic ward during consumption of a liquid diet of 300 kcal/day with 30 g of protein. Rapid improvement occurred in the glycemic indices of the diabetic subjects, with mean (+/- SEM) fasting plasma glucose falling from 291 +/- 21 to 95 +/- 6 mg/dl (P less than 0.001) and total glycosylated hemoglobin from 13.1 +/- 0.7% to 8.8 +/- 0.3% (P less than 0.001) (normal reference range 5.5-8.5%). Lipid elevations were normalized with plasma triglycerides reduced to less than 100 mg/dl and total plasma cholesterol to less than 150 mg/dl in both groups. Hormonal and substrate responses were also comparable between groups with reductions in insulin and triiodothyronine and moderate elevations in blood and urinary ketoacid levels without a corresponding rise in free fatty acids. Electrolyte balance for sodium, potassium, calcium, and phosphorus was initially negative but approached equilibrium by completion of the study. Magnesium, in contrast, remained in positive balance in both groups throughout. Total nitrogen loss varied widely among all subjects, ranging from 70 to 367 g, and showed a strong positive correlation with initial lean body mass (N = 0.83, P less than 0.001) and total weight loss (N = 0.87, P less than 0.001). The nondiabetic group, which had a significantly greater initial body weight and lean body mass than the diabetic group, also had a significantly greater weight loss of 450 +/- 31 g/day compared with 308 +/- 19 g/day (P less than 0.01) in the diabetic subjects. The composition of the weight lost at completion was similar in both groups and ranged from 21.6% to 31.3% water, 3.9% to 7.8% protein, and 60.9% to 74.5% fat. The contribution of both water and protein progressively decreased and fat increased, resulting in unchanged caloric requirements during the diet. This study demonstrates that short-term treatment with a very-low-calorie diet in both obese diabetic and nondiabetic subjects results in: safe and effective weight loss associated with the normalization of elevated glucose and lipid levels, a large individual variability in total nitrogen loss determined principally by the initial lean body mass, and progressive increments in the contribution of fat to weight loss with stable caloric requirements and no evidence of a hypometabolic response.
PMID: 3510922 [PubMed - indexed for MEDLINE]</div>
If my math is correct, this study shows greater weight loss than expected if one is using the ~3600 kcal / lb rule. However, only 59% of that was fat.
<div class='quotetop'>QUOTE </div><div class='quotemain'>Am J Clin Nutr. 1984 Sep;40(3):611-22. Links
Variability in body protein loss during protracted, severe caloric restriction: role of triiodothyronine and other possible determinants.
Yang MU, van Itallie TB.
Six morbidly obese subjects were maintained in a metabolic ward for 64 days on liquid diets providing 600 to 800 kcal/day. Three received protein at a level of 1.5 g/kg desirable weight per day. The other three were given an identical diet in which half the protein was replaced by carbohydrate. Because there were no significant differences in either mean protein or mean fat losses between the two groups, the data on all six subjects were combined. Over the 64 days, the mean weight loss (+/- SEM) of the subjects per 1000 kcal deficit was 174.3 +/- 25.5 g. The composition of this weight loss was 36.0% water, 58.9% fat, and 5.1% protein. Although the rate of fat loss was relatively constant throughout the study, wide interindividual variations in cumulative protein (nitrogen) deficit were observed. Total nitrogen losses per subject ranged from 90.5 to 278.7 g. Cumulative nitrogen loss during the first 16 days tended to correlate negatively with initial mean fat cell size and positively with initial lean body mass. Most notable was the strong negative correlation between the size of the decrease in serum triiodothyronine over the 64-day study and the magnitude of the concurrent cumulative N deficit. During severe caloric restriction, one's ability to decrease circulating serum triiodothyronine levels may be critical to achievement of an adaptational decrease in body protein loss.
PMID: 6383009 [PubMed - indexed for MEDLINE]</div>
<div class='quotetop'>QUOTE </div><div class='quotemain'>Postgrad Med J. 1984;60 Suppl 3:66-73.Links
Nitrogen balance studies during modified fasting.
Wechsler JG, Wenzel H, Swobodnik W, Ditschuneit HH, Ditschuneit H.
Protein or nitrogen depletion may be harmful and deleterious as reports of deaths in obese patients fed by liquid protein diets have shown. The aim of our studies was to determine the protein losses (by urinary nitrogen losses) during treatment of obesity with modified fasting over four weeks under inpatient conditions. Sixty-one patients were treated in our metabolic ward with modified fasting randomized into four groups. The daily diet consisted of 33-50 g protein/day, 1-10 g fat/day and 25-45 g carbohydrates/day thus providing 240 to 450 kcal/day or 1.0 to 1.9 MJ. The mean weight losses ranged between 11.0 +/- 0.7 kg and 13.9 +/- 0.9 kg in 28 days. The acceptability and compliance of the four applied diets were excellent and no severe side effects could be observed. The nitrogen balances could be equilibrated from the third week on. The composition of weight lost during modified fasting was as follows. The percentage of body protein ranged between 3% and 16% and the percentage of adipose tissue between 63% and 79% of the total weight loss. Therefore modified fasting represents a very effective and safe therapy of massive obesity.
PMID: 6514657 [PubMed - indexed for MEDLINE]</div>