Influence of energy and nitrogen contents of enteral diets on nitrogen balance: a double blind prospective controlled clinical trial.

Results of recent controlled studies show that because of difficulties in administering adequate quantities of enteral diet, positive nitrogen balance is not consistently achieved during enteral feeding. In order to determine whether nitrogen balance can be improved in routine clinical practice by prescribing enteral diets containing higher concentrations of nutrients, 118 patients with normal gastrointestinal function needing enteral nutrition were randomised to receive daily 21 of one of three polymeric diets: Standard diet (1.0 kcal/ml; 6.3 gN/l), Energy Dense diet (1.5 kcal/ml; 7.8 gN/l), and Energy-Nitrogen Dense diet (1.5 kcal/ml; 9.4 gN/l. The three diets, administered by continuous nasogastric infusion, were equally well tolerated. Results were analysed only for patients fed five or more days and who received at least 60% of prescribed enteral diet (n = 42). Positive nitrogen balance was achieved only in the patients receiving the Energy-Nitrogen Dense diet (n = 16; + 1.6 (SE) 0.6 gN/d, compared with the Standard diet (n = 12; -3.8 (1.1) gN/d; p less than 0.001), and the Energy Dense diet (m = 14; -1.9 (0.8) gN/d; p less than 0.005). As the findings of this prospective controlled trial show that positive nitrogen balance was not consistently achieved by administering 21 enteral diet containing up to 15.6 gN, consideration could, therefore, be given to routinely using enteral diets containing up to 9.4 gN/l.     

Do patients with moderately impaired gastrointestinal function requiring enteral nutrition need a predigested nitrogen source? A prospective crossover controlled clinical trial.

This prospective double blind randomised seven day crossover controlled clinical trial was carried out to determine whether enterally fed patients with moderately impaired gastrointestinal function require a predigested nitrogen (N) source compared with whole protein. Twelve malnourished patients with varying gastrointestinal abnormalities, who required enteral feeding, received 2.25 l of one of two isocaloric isonitrogenous enteral diets (1 kcal/ml, 4.8 g nitrogen/l) containing either predominantly medium chain peptides (tetra or higher peptides) or whole protein as the nitrogen source. Nitrogen absorption and balance were calculated from dietary intake and analysis of 24 hour total urinary and faecal nitrogen for the last five days of each study period. There was no significant difference in either stool weight (110 (SEM) (49) v 111 (32) g/d), nitrogen absorption (91 (2) v 89 (2)%) or nitrogen balance (+1.0 (1.3) v +0.6 (1.4) g nitrogen/d) between the peptide and whole protein nitrogen sources when all patients are considered. There was, however, evidence to suggest a nutritional advantage from administering an enteral diet whose nitrogen source comprises oligopeptides, rather than whole protein, to a subgroup of patients with small bowel disease.     

Growth hormone and pulmonary disease. Metabolic effects in patients receiving parenteral nutrition

Six severely malnourished patients with chronic obstructive pulmonary disease were maintained for 3 days with infusions of 5% dextrose in water followed by 12 days of eucaloric total parenteral nutrition. On days 8 through 11, they received 30 micrograms/d of growth hormone and twice this amount on days 11 through 15. Growth hormone had no significant effects on the plasma concentration of glucose, cortisol, or glucagon but caused a 50% increase in insulin and a 250% increase in somatomedin C concentrations. A positive nitrogen balance of 2 g/d due to growth hormone was probably mediated by insulin. Growth hormone-induced increases in energy expenditure and fat oxidation and decrease in glucose oxidation cannot be accounted for by insulin. The ability of growth hormone to improve nitrogen balance may be particularly important for malnourished patients with chronic obstructive pulmonary disease who, because of their pulmonary insufficiency, are intolerant of excess nutrients.     

A metabolic ward study of a high protein, very-low-energy diet

Seven obese women were placed on a liquid formula diet providing 560 kcal (2.4 MJ) and 70 g protein daily and studied under metabolic ward conditions for four weeks. The diet was well tolerated and hunger sensations were minimal. Mean weight loss was 10.47 kg for the four weeks. A positive nitrogen balance was achieved within two weeks in most patients, but despite this serum prealbumin levels fell as did the excretion of 3-methylhistidine in the urine. Plasma beta-hydroxybutyrate and urate levels rose during the first two weeks but remained constant thereafter. The characteristic decrease in plasma triiodothyronine levels and increase in reverse triiodothyronine levels seen with fasting and other very-low-calorie diets were also observed with this diet. Potassium losses were minimal and no changes in electrocardiograms were seen. This diet would appear to be an acceptable, effective and safe means of achieving rapid weight loss in obesity.     

Benefit of low-fat over low-carbohydrate diet on endothelial health in obesity

Obesity is associated with impaired endothelial-dependent flow-mediated dilation, a precursor to hypertension and atherosclerosis. Although dieting generally improves cardiovascular risk factors, the direct effect of different dietary strategies on vascular endothelial function is not known. The purpose of this study was to test the hypothesis that a low-fat (LF) diet improves endothelial function compared with an isocaloric low-carbohydrate (LC) diet. Obese (n=20; body mass index: 29 to 39; mean systolic blood pressure: 107 to 125 mm Hg) and otherwise healthy volunteers were randomly assigned to either the American Heart Association modeled LF (30% fat calories) diet or an isocaloric LC Atkins' style diet (20 g of carbohydrates) for 6 weeks (4-week weight loss and 2-week maintenance phase). Brachial flow-mediated dilation and dilation to nitroglycerin were measured with ultrasound using automated edge detection technology (baseline, week 2, and week 6). Blood pressure, weight loss, and cholesterol profiles were measured throughout the study. Weight loss was similar in LF (100+/-4 to 96.1+/-4 kg; P<0.001) and LC (95.4+/-4 to 89.7+/-4 kg; P<0.001) diets. Blood pressure decreased similarly in both groups (LF: 8/5 mm Hg; LC: 12/6 mm Hg) at 6 weeks. After 6 weeks, the percentage of flow-mediated dilation improved (1.9+/-0.8; P<0.05) in the LF diet but was reduced in the LC diet (-1.4+/-0.6; P<0.05) versus baseline. Dilation to nitroglycerin and lipid panels was similar at 0, 2, and 6 weeks. Despite similar degrees of weight loss and changes blood pressure, LF diets improved brachial artery flow-mediated dilation over LC diets. LF diets may confer greater cardiovascular protection than LC diets.     

Comparison of a low-fat diet to a low-carbohydrate diet on weight loss, body composition, and risk factors for diabetes and cardiovascular disease in free-living, overweight men and women

Overweight and obese men and women (24-61 yr of age) were recruited into a randomized trial to compare the effects of a low-fat (LF) vs. a low-carbohydrate (LC) diet on weight loss. Thirty-one subjects completed all 10 wk of the diet intervention (retention, 78%). Subjects on the LF diet consumed an average of 17.8% of energy from fat, compared with their habitual intake of 36.4%, and had a resulting energy restriction of 2540 kJ/d. Subjects on the LC diet consumed an average of 15.4% carbohydrate, compared with habitual intakes of about 50% carbohydrate, and had a resulting energy restriction of 3195 kJ/d. Both groups of subjects had significant weight loss over the 10 wk of diet intervention and nearly identical improvements in body weight and fat mass. LF subjects lost an average of 6.8 kg and had a decrease in body mass index of 2.2 kg/m2, compared with a loss of 7.0 kg and decrease in body mass index of 2.1 kg/m2 in the LC subjects. The LF group better preserved lean body mass when compared with the LC group; however, only the LC group had a significant decrease in circulating insulin concentrations. Group results indicated that the diets were equally effective in reducing systolic blood pressure by about 10 mm Hg and diastolic pressure by 5 mm Hg and decreasing plasminogen activator inhibitor-1 bioactivity. Blood beta-hydroxybutyrate concentrations were increased in the LC only, at the 2- and 4-wk time points. These data suggest that energy restriction achieved by a very LC diet is equally effective as a LF diet strategy for weight loss and decreasing body fat in overweight and obese adults.     

Adherence to a low‐fat vs. low‐carbohydrate diet differs by insulin resistance status

Previous research shows diminished weight loss success in insulin‐resistant (IR) women assigned to a low‐fat (LF) diet compared to those assigned to a low‐carbohydrate (LC) diet. These secondary analyses examined the relationship between insulin‐resistance status and dietary adherence to either a LF‐diet or LC‐diet among 81 free‐living, overweight/obese women [age = 41.9 ± 5.7 years; body mass index (BMI) = 32.6 ± 3.6 kg/m²]. This study found differential adherence by insulin‐resistance status only to a LF‐diet, not a LC‐diet. IR participants were less likely to adhere and lose weight on a LF‐diet compared to insulin‐sensitive (IS) participants assigned to the same diet. There were no significant differences between IR and IS participants assigned to LC‐diet in relative adherence or weight loss. These results suggest that insulin resistance status may affect dietary adherence to weight loss diets, resulting in higher recidivism and diminished weight loss success of IR participants advised to follow LF‐diets for weight loss.     

Utilization of calcium L-phenyllactate as a substitute for phenylalanine by uremic patients

The efficacy of calcium L-phenyllactate as a substitute for phenylalanine was examined in eight uremic patients who were also receiving calcium salts of the α-keto analogues of the branched-chain amino acids and the D,L-α-hydroxy analogue of methionine in addition to the remaining four essential amino acids themselves. Nitrogen balance, corrected for urea accumulation but not for cutaneous losses, was measured while the patients ate a virtually protein-free diet supplemented with the above mixture and glycine as a source of nonessential nitrogen. Two men were in negative nitrogen balance whether receiving this regimen (?2.58 ± 0.43 g N/day) or 21.5 g/day of essential amino acids, including 2 g of phenylalanine (?2.76 ± 0.46 g N/day). There was no apparent reason for their excessive catabolism. In contrast, six women had an average measured nitrogen balance of +0.73 ± 0.23 g N/day on this regimen. If an estimate for unmeasured nitrogen losses is included in their measured nitrogen balances, one patient was in positive balance (+0.90 g N/day), three in neutral balance (+0.43, +0.42, +0.11 g N/day) and two in negative balance, (?0.26, ?0.56 g N/day), yielding an average balance of +0.23 ± 0.23 g N/day. These data contrast with reported negative balances of ?1.8 to ?3.8 g N/day of subjects eating a phenylalanine-free diet. We conclude that in this group of six uremic patients, calcium L-phenyllactate was converted to phenylalanine and utilized to maintain nitrogen balance.     

Vegetable versus animal protein diet in cirrhotic patients with chronic encephalopathy. A randomized cross-over comparison

Abstract. In a randomized cross-over comparison, the effects of a mainly vegetable protein diet were compared with an animal protein diet in eight patients with cirrhosis and chronic permanent encephalopathy, under optimum lactulose therapy. After a run-in period, patients were fed two equi-caloric, equi-nitrogenous diets for 7 days (71 g total proteins), containing either 50 g protein of animal origin or 50 g vegetable proteins. In the last 3 days of each period, nitrogen balance was significantly better during the vegetable protein diet (+ 0.2 (SD 1.4) g vs. — 1.7 (2.4): P < 0.01), the difference being entirely due to a reduced urinary nitrogen excretion. Average daytime integrated blood glucose was slightly higher during vegetable proteins, whereas insulin, plasma amino acids and ammonia were lower. The clinical grading of encephalopathy improved slightly on vegetable proteins, and psychometric tests improved significantly, but remained grossly abnormal. Compliance to dietary manipulation was good. The data prove that a mainly vegetable protein diet is worthwhile in cirrhotic patients with chronic encephalopathy under optimum lactulose therapy. Improved nitrogen balance may be related to more effective nitrogen use for protein synthesis, probably due to blunted hormonal response, and largely outweighs the effects on encephalopathy.     

Effect of total enteral nutrition on the short-term outcome of severely malnourished cirrhotics. A randomized controlled trial

Thirty-five severely malnourished cirrhotic patients were randomized to receive either enteral-tube feeding as the sole nutritional support (n = 16) or an isocaloric, isonitrogenous, low-sodium standard oral diet (n = 19). Both groups were homogeneous regarding age, sex distribution, etiology of liver cirrhosis, history of previous complications, clinical status, liver and renal function, modified Child's score, and nutritional status at admission. The enteral formula diet was energy dense, containing 40 mmol Na/day, whole protein plus branched-chain amino acids, medium- and long-chain triglycerides, and maltodextrin. It supplied 2115 kcal/day. The amount of vitamins and trace elements was at the upper limit of the recommended dietary allowances. The orally fed patients were encouraged to eat all meals served. Total enteral nutrition was well tolerated without major complications. Serum albumin and Child's score improved in the enterally fed patients but not in controls. Mortality rate while in the hospital was lower in patients on enteral feeding than in controls (12% vs 47%). These results show that total enteral nutrition is safe and effective in improving the short-term clinical outcome in severely malnourished cirrhotics.     

Level of dietary protein impacts whole body protein turnover in trained males at rest

The current investigation examined the effect of variations in protein intake on Whole body protein turnover (WBPTO) at rest in endurance-trained males. Whole body protein turnover is influenced by both diet and exercise. Whether endurance athletes require more protein than the non-exerciser remains equivocal. Five male runners (21.3 +/- 0.3 years, 179 +/- 2 cm, 70.6 +/- 0.1 kg, 8.7% +/- 0.4% body fat, 70.6 +/- 0.1 VO(2)max) participated in a randomized, crossover design diet intervention where they consumed either a low-protein (LP; 0.8 g/kg), moderate-protein (MP; 1.8 g/kg), or high-protein (HP; 3.6 g/kg) diet for 3 weeks. Whole body protein turnover (Ra, leucine rate of appearance; NOLD, nonoxidative leucine disposal; and Ox, leucine oxidation), nitrogen balance, and substrate oxidation were assessed at rest following each dietary intervention period. The HP diet increased leucine Ra (indicator of protein breakdown; 136.7 +/- 9.3, 129.1 +/- 7.4, and 107.8 +/- 3.1 micromol/[kg . h] for HP, MP, and LP diets, respectively) and leucine Ox (31.0 +/- 3.6, 26.2 +/- 4.3, and 18.3 +/- 0.6 micromol/[kg . h] for HP, MP, and LP diets, respectively) compared with LP diet (P < .05). No differences were noted in nonoxidative leucine disposal (an indicator of protein synthesis) across diets. Nitrogen balance was greater for HP diet than for MP and LP diets (10.2 +/- 0.7, 1.8 +/- 0.6, and -0.3 +/- 0.5 for HP, MP, and LP diets, respectively). Protein oxidation increased with increasing protein intake (54% +/- 6%, 25% +/- 1%, and 14% +/- 2% for HP, MP, and LP diets, respectively). Findings from this study show that variations in protein intake can modulate WBPTO and that protein intake approximating the current recommended dietary allowance was not sufficient to achieve nitrogen balance in the endurance-trained males in this investigation. Our results suggest that a protein intake of 1.2 g/kg or 10% of total energy intake is needed to achieve a positive nitrogen balance. This is not a concern for most endurance athletes who routinely consume protein at or above this level.     

Perioperative artificial nutrition in malnourished gastrointestinal cancer patients

AIM: To investigate the potential role of perioperative nutrition in reducing complications and mortality in malnourished gastrointestinal cancer patients. METHODS: Four hundred and sixty-eight elective moderately or severely malnourished surgical patients with gastric or colorectal cancers defined by the subjective global assessment (SGA) were randomly assigned to 7 d preoperative and 7 d postoperative parenteral or enteral nutrition vs a simple control group. The nutrition regimen included 24.6±5.2 kcal/kg per d non-protein and 0.23±0.04 g nitrogen /kg per d. Control patients did not receive preoperative nutrition but received 600±100 kcal non-protein plus or not plus 62±16 g crystalline amino acids postoperatively. RESULTS: Complications occurred in 18.3% of the patients receiving nutrition and in 33.5% of the control patients (P=0.012). Fourteen patients died in the control group and 5 in those receiving nutrition. There were significant differences in the mortality between the two groups (2.1% vs 6.0%, P=0.003). The total length of hospitalization and postoperative stay of control patients were significantly longer (29 vs 22 d, P = 0.014) than those of the studied patients (23 vs 12 d. P=0.000). CONCLUSION: Perioperative nutrition support is beneficial for moderately or severely malnourished gastrointestinal cancer patients and can reduce surgical complications and mortality.     

A semi-elemental diet with low osmolarity and high content of hydrolyzed lactalbumin in the treatment of acute diarrhea in malnourished children

Thirty-eight moderately to severely malnourished children with severe acute or subacute diarrhea were treated according to two different feeding schemes, divided at random half of the children received semi-elemental diet (SED) with an osmolarity of 302 milliosmol per liter, a low lactose content and a relatively high content of lactalbumine hydrolysate (1 g/100 ml). The other half of the patients received available proprietory formulas or diluted cow's milk with added carbohydrates. The results obtained showed that the children who were fed the SED had a better average weight gain during the first three weeks of hospitalization compared to the control group. The children receiving the SED also required a smaller number or rehydrations.     

Bio-utilization of protein, calcium and zinc from diets based on rice and beans, in human beings

Nine male healthy adults volunteers of average body weight 69.51 +/- 11.59 kg were submitted to 3 experimental diets: I complete diet, containing rice and beans (RB): II--low protein, low calcium: III--vegetable diet containing RB. The diets were consumed "ad libitum". The total energy intake in each dietary period were: 46.04 +/- 9.18; 37.57 +/- 9.04; 55.27 +/- 7.18 respectively. The average free choice for the proportion of rice/beans was 1.22 and 1.35 in the periods I and III. The protein balance was positive only for the diet I and the balance of calcium was positive in diets I and II. Zinc didn't attained positive balance neither in diet I. It is suggested that the presence of beans in diets I and III plays an important role in decreasing the bio-utilization of the studied nutrients.     

Relative nutritional value of whole protein, hydrolysed protein and free amino acids in man.

To compare their effects on nitrogen balance, diets containing either lactalbumin whole protein, its peptide-rich enzymic hydrolysate or an equivalent mixture of free amino acids as the sole source of dietary nitrogen were fed to two healthy subjects, each studied for 38 days on two separate occasions. The nitrogen intake (47 mg/kg body wt/day) induced a state of negative nitrogen balance, stimulating nitrogen conservation. Net daily nitrogen balance (mean +/- SD) in subject 1 was -0.23 +/- 0.72 g (amino acids) vs + 0.05 +/- 0.52 g (protein) and -0.21 +/- 0.58 g (amino acids) vs -0.05 +/- 0.57 g (hydrolysate), and in subject 2, -0.19 +/- 0.60 g (amino acids) vs -0.16 +/- 0.51 g (protein) and -0.42 +/- 0.35 g (amino acids) vs -0.62 +/- 0.34 g (hydrolysate). Analysis of these results by the cumulative sum technique showed no significant differences in the effect of the three nitrogen sources on nitrogen balance. This study indicates that there is no nutritional evidence to support the current practice of prescribing expensive enteral diets containing peptides or amino acids rather than the much cheaper whole protein to patients with normal gastrointestinal function.     

Effects of dietary protein on urinary calcium in normal subjects and in patients with nephrolithiasis.

The effect of high-protein diets on the excretion of calcium in urine was evaluated in four normal persons and in four patients with nephrolithiasis. All subjects were housed in a metabolic unit and given constant metabolic diets each day containing 0.5 g protein/kg and 300–600 mg calcium, 1000 mg phosphorus, and 69 mEq sodium. During the experimental phase, each person received an additional 1.5 g protein/kg/day consisting of purified casein, gluten, lactalbumin, and gelatin. There was a consistent increase in urinary calcium with the high-protein diet, averaging 88% above control in the normals and 82% in the patients. In addition, the normal subjects showed significant (p < 0.05) increases in urinary phosphorus (mean increases, 219 ± 53 mg/d, mean ± SE), nitrogen (8.8 ± 0.9 g/d), titratable acid (19 ± 5 mEq/d), and ammonium (22 ± 3 mEq/d), whereas the patients showed increases in urinary magnesium (18 ± 2 mg/d), nitrogen (12 ± 1.0 g/d), and ammonium (34 ± 2 mEq/d), and in creatinine clearance (14 ± 3 ml/min). In both groups, there was a small increase in the filtered, excreted, and reabsorbed calcium and a small decrease in the percentage reabsorption of calcium. Serum chemical values did not change from values with the low-protein diet. In two of the patients who were known to be hyperabsorbing calcium, sodium cellulose phosphate (chelator of intestinal calcium) reversed the increase in urinary calcium produced by the high-protein diet. In the remaining patients, neither sodium cellulose phosphate nor a low-calcium diet could counteract the increase in excretion of calcium with the diet. It is concluded that a high-protein diet can increase urinary calcium by altering renal function and/or increasing intestinal absorption of calcium and that dietary protein must be considered in the evaluation and treatment of patients with hypercalciuria and nephrolithiasis.     

Effect of a very-high-fiber vegetable, fruit, and nut diet on serum lipids and colonic function

We tested the effects of feeding a diet very high in fiber from fruit and vegetables. The levels fed were those, which had originally inspired the dietary fiber hypothesis related to colon cancer and heart disease prevention and also may have been eaten early in human evolution. Ten healthy volunteers each took 3 metabolic diets of 2 weeks duration. The diets were: high-vegetable, fruit, and nut (very-high-fiber, 55 g/1,000 kcal); starch-based containing cereals and legumes (early agricultural diet); or low-fat (contemporary therapeutic diet). All diets were intended to be weight-maintaining (mean intake, 2,577 kcal/d). Compared with the starch-based and low-fat diets, the high-fiber vegetable diet resulted in the largest reduction in low-density lipoprotein (LDL) cholesterol (33% +/- 4%, P <.001) and the greatest fecal bile acid output (1.13 +/- 0.30 g/d, P =.002), fecal bulk (906 +/- 130 g/d, P <.001), and fecal short-chain fatty acid outputs (78 +/- 13 mmol/d, P <.001). Nevertheless, due to the increase in fecal bulk, the actual concentrations of fecal bile acids were lowest on the vegetable diet (1.2 mg/g wet weight, P =.002). Maximum lipid reductions occurred within 1 week. Urinary mevalonic acid excretion increased (P =.036) on the high-vegetable diet reflecting large fecal steroid losses. We conclude that very high-vegetable fiber intakes reduce risk factors for cardiovascular disease and possibly colon cancer. Vegetable and fruit fibers therefore warrant further detailed investigation.     

Effect of the ingestion of dietary fiber on the digestibility of lipids in a sorghum-consuming African population

Digestibility measurements were carried out on 12 men. Their habitual diet, deficient in animal products, is based on sorghum meals which supply between 2.4 and 4.2 g of crude fiber per 100 g of dry matter. Over three 11-day periods, the subjects received 3 successive diets (A, B and C) which supplied respectively 3.3, 4.8 and 5.4 g of crude fiber per 100 g of dry matter. Reduced lipids digestibility was noted, even for diet A which was the poorest in fiber content. No difference was observed between diet A and diet B (92.3 and 91.7% respectively). The apparent digestibility of lipids dropped to 86.1 with diet C. True digestibility of lipids is hidden by poorly digestible dietary lipids. Lipid losses increased more rapidly than nitrogen losses with increasing of fiber content in diets. On these regimens, there were no significant changes in concentrations of fecal fat. Concentration of fecal nitrogen decreases for diets B and C.     

Potential life-threatening cardiac arrhythmias associated with a conventional hypocaloric diet

Nine obese children (mean age 12.7 years, mean overweight 74.2%) were treated for 3 weeks with a very low calorie diet containing high quality protein. Eight patients (patients A) received a commercially available diet (240 kcal/1004 kJ/day) and 1 patient (patient B) a homemade dietary regimen (500 kcal/2100 kJ/day). Both preparations were supplemented with micronutrients; however, the daily intake of minerals was significantly less in patient B. All patients were monitored for the appearance of cardiac arrhythmias by frequent 24-hour Holter recordings. In patients A the mean loss of body weight was 9.4 +/- 2.4 kg, patient B lost 8.7 kg. The mean daily nitrogen balance was negative (patients A: 10.2 g/day, patient B: 6.8 g/day). Frequent blood chemistry evaluations were unremarkable. On the 14th day of treatment patient B developed arrhythmias (ventricular couplets, non-sustained ventricular tachycardias); in patients A no ventricular dysrhythmias were observed. Our data suggest that very low calorie diets containing protein of high biologic value can be associated with potentially dangerous arrhythmias.     

Very low calorie diets: their efficacy, safety, and future

Very low calorie diets used to treat moderate and severe obesity produce average weight losses of 20 kg in 12 weeks. This paper reviews the development of very low calorie diets from research on fasting in the late 1950s and examines data on the amount of dietary protein needed to achieve positive nitrogen balance. The desirability of including carbohydrate in the diet, the choice of protein sources (formula versus animal protein), and the anorectic value of ketosis are discussed, as are patient selection and the clinical course of the diet. As contrasted to the earlier "liquid protein" diets that were associated with at least 60 deaths, very low calorie diets of high-quality protein appear safe when limited to 3 months or less under careful medical supervision. Evidence of this safety is provided by the results of 24-hour Holter monitoring and the fact that no diet-related fatalities have been reported in over 10 000 cases. The major problem to be resolved is the maintenance of the large weight losses achieved with these diets.