Economic Analysis of a School‐Based Obesity Prevention Program

Objective: To assess the cost‐effectiveness and cost‐benefit of Planet Health, a school‐based intervention designed to reduce obesity in youth of middle‐school age children. Research Methods and Procedures: Standard cost‐effectiveness analysis methods and a societal perspective were used in this study. Three categories of costs were measured: intervention costs, medical care costs associated with adulthood overweight, and costs of productivity loss associated with adulthood overweight. Health outcome was measured as cases of adulthood overweight prevented and quality‐adjusted life years (QALYs) saved. Cost‐effectiveness ratio was measured as the ratio of net intervention costs to the total number of QALYs saved, and net‐benefit was measured as costs averted by the intervention minus program costs. Results: Under base‐case assumptions, at an intervention cost of $33, 677 or $14 per student per year, the program would prevent an estimated 1.9% of the female students (5.8 of 310) from becoming overweight adults. As a result, an estimated 4.1 QALYs would be saved by the program, and society could expect to save an estimated $15, 887 in medical care costs and $25, 104 in loss of productivity costs. These findings translated to a cost of $4305 per QALY saved and a net saving of $7313 to society. Results remained cost‐effective under all scenarios considered and remained cost‐saving under most scenarios. Discussion: The Planet Health program is cost‐effective and cost‐saving as implemented. School‐based prevention programs of this type are likely to be cost‐effective uses of public funds and warrant careful consideration by policy makers and program planners.     

Bringing Stem Cell‐Based Therapies for Type 1 Diabetes to the Clinic: Early Insights from Bioprocess Economics and Cost‐Effectiveness Analysis

Differentiation of pluripotent stem cells (PSCs) into β cells could provide insulin independence for type 1 diabetes (T1D) patients. This approach would reduce the clinical complications that most patients managed on intensive insulin therapy (IIT) face. However, bottlenecks of PSC manufacturing and limited engraftment of encapsulated cells hinder the long‐term effectiveness of these therapies. A bioprocess decision‐support tool is combined with a disease state‐transition model to evaluate the cost‐effectiveness of the stem cell‐based therapy against IIT. Clinical effectiveness is assessed in quality‐adjusted life years (QALYs). Manufacturing costs per patient reduce from $430 000 to $160 000 with optimization of batch size and annual demand. For 96% of the patients, cell therapy improves the quality of life compared to IIT. Cost savings are achieved for 2% of the population through prevention of renal disease. The therapy is cost‐effective for 3.4% of patients when a willingness to pay (WTP) of up to $150 000 per QALY is considered. A 75% cost reduction in the cell therapy price increases cost‐effectiveness likelihood to 51% at $100 000 per QALY. This study highlights the need for scalable manufacturing platforms for stem cell therapies, as well as to prioritizing access to the therapy to patients with an increased likelihood of costly complications.     

Life‐history trade‐offs under different larval diets in Drosophila suzukii (Diptera: Drosophilidae)

Most larval drosophilids eat the microorganisms that develop in rotting fruit, a relatively protein‐rich resource. By contrast, the spotted‐wing Drosophila suzukii Matsumara (Diptera: Drosophilidae) uniquely develops in ripening fruit, a protein‐poor, carbohydrate‐rich resource. This shift in larval nutritional niche has led to D. suzukii being a significant agricultural pest in the U.S.A. and Europe. Although occupying a new niche may benefit a species by reducing competition, adaptation in host use may generate trade‐offs affecting fitness. To test the hypothesis that fitness trade‐offs will change with adaptation to novel larval diets, D. suzukii larval development on either a diet of a fresh, ripe blueberry (a natural host) or standard artificial Drosophila media (protein‐rich) is compared and the effect of diet on development time from egg to adult, adult body size and male wing spot area, and female fecundity is assessed. Larval development time differs, with larvae on the blueberry emerging as adults earlier than those on the artificial medium, although other fitness measures do not vary between the two diets. In addition, the faster development time on a blueberry does not trade off with body size as expected, although early fecundity is delayed in females that develop on blueberries. Thus, adaptation to a novel larval diet environment does not come at a cost to the ability to develop in protein‐rich resources.     

Endothelial function and weight loss: Comparison of low‐carbohydrate and low‐fat diets

Objective: The effect of weight loss on obesity‐associated endothelial dysfunction is not clear because of conflicting data, demonstrating both improvement and no change in endothelial function after weight loss in obese subjects. A 2‐year prospective study (n = 121) was conducted to examine: (1) the effect of obesity and weight loss (either a low‐carbohydrate or and low‐fat diet) on flow mediated vasodilatation (FMD), a measure of endothelial function. Design and Methods: Participants reduced body weight by 7.1% ± 4.4%, 8.7% ± 6.8%, 7.1% ± 7.8%, and 4.1% ± 7.7% at 3, 6, 12, and 24 months, respectively with no significant differences between the low‐fat and low‐carbohydrate groups. Results: Endothelial function was inversely correlated with waist circumference, triglyceride level, and directly correlated with leptin in obese persons prior to weight loss. These weight losses did not confer any improvements in FMD. There were no differences between the low‐fat and low‐carbohydrate diets in FMD at any time point. At 6 months (r = 0.26, P = 0.04) and 1 year (r =0.28, P = 0.03), there were positive correlations between change in FMD and change in leptin but not at 2 years. Conclusion: There was no significant improvement in endothelial function after 7.1% ± 7.8% weight loss at 1 year and 4.1% ± 7.7% at 2 years, achieved by either a low carbohydrate or a low fat diet.     

Effect of Energy‐Reduced Diets High in Dairy Products and Fiber on Weight Loss in Obese Adults

Objective: Studies suggest that high‐dairy and high‐fiber/low‐glycemic index diets may facilitate weight loss, but data are conflicting. The effects on weight loss and body fat of a high‐dairy diet and a diet high in dairy and fiber and low in glycemic index were compared with a standard diet. Research Methods and Procedures: Ninety obese subjects were recruited into a randomized trial of three diets designed to provide a calorie deficit of 500 calories/d over a 48‐week period. The study compared a moderate (not low)‐calcium diet with a high‐calcium diet. Results: Seventy‐two subjects completed the study. Significant weight and fat loss occurred with all three diets. A diet with 1400 mg of calcium did not result in greater weight (11.8 ± 6.1 kg) or fat (9.0 ± 6.0 kg) loss than a diet with 800 mg of calcium (10.0 ± 6.8 and 7.5 ± 6.6 kg, respectively). A diet with 1400 mg of calcium, increased fiber content, and fewer high‐glycemic index foods did not result in greater weight (10.6 ± 6.8 kg) or fat (8.5 ± 7.8 kg) loss than the standard diet with 800 mg of calcium. Lipid profile, high‐sensitivity C‐reactive protein, leptin, fasting glucose, and insulin improved significantly, but there were no significant differences between the experimental diets and the control diet. Discussion: We found no evidence that diets higher than 800 mg of calcium in dairy products or higher in fiber and lower in glycemic index enhance weight reduction beyond what is seen with calorie restriction alone.     

Effects of a Low Carbohydrate Weight Loss Diet on Exercise Capacity and Tolerance in Obese Subjects

Dietary restriction and increased physical activity are recommended for obesity treatment. Very low carbohydrate diets are used to promote weight loss, but their effects on physical function and exercise tolerance in overweight and obese individuals are largely unknown. The aim of this study was to compare the effects of a very low carbohydrate, high fat (LC) diet with a conventional high carbohydrate, low fat (HC) diet on aerobic capacity, fuel utilization during submaximal exercise, perceived exercise effort (RPE) and muscle strength. Sixty subjects (age: 49.2 ± 1.2 years; BMI: 33.6 ± 0.5 kg/m²) were randomly assigned to an energy restricted (～6–7 MJ, 30% deficit), planned isocaloric LC or HC for 8 weeks. At baseline and week 8, subjects performed incremental treadmill exercise to exhaustion and handgrip and isometric knee extensor strength were assessed. Weight loss was greater in LC compared with HC (8.4 ± 0.4% and 6.7 ± 0.5%, respectively; P = 0.01 time × diet). Peak oxygen uptake and heart rate were unchanged in both groups (P > 0.17). Fat oxidation increased during submaximal exercise in LC but not HC (P < 0.001 time × diet effect). On both diets, perception of effort during submaximal exercise and handgrip strength decreased (P ≤ 0.03 for time), but knee extensor strength remained unchanged (P > 0.25). An LC weight loss diet shifted fuel utilization toward greater fat oxidation during exercise, but had no detrimental effect on maximal or submaximal markers of aerobic exercise performance or muscle strength compared with an HC diet. Further studies are required to determine the interaction of LC diets with regular exercise training and the long‐term health effects.     

Cost effectiveness analysis of a randomised trial of acupuncture for chronic headache in primary care

Objective To evaluate the cost effectiveness of acupuncture in the management of chronic headache.Design Cost effectiveness analysis of a randomised controlled trial.Setting General practices in England and Wales.Participants 401 patients with chronic headache, predominantly migraine.Interventions Patients were randomly allocated to receive up to 12 acupuncture treatments over three months from appropriately trained physiotherapists, or to usual care alone.Main outcome measure Incremental cost per quality adjusted life year (QALY) gained.Results Total costs during the one year period of the study were on average higher for the acupuncture group (£403; $768; €598) than for controls (£217) because of the acupuncture practitioners'' costs. The mean health gain from acupuncture during the one year of the trial was 0.021 quality adjusted life years (QALYs), leading to a base case estimate of £9180 per QALY gained. This result was robust to sensitivity analysis. Cost per QALY dropped substantially when the analysis incorporated likely QALY differences for the years after the trial.Conclusions Acupuncture for chronic headache improves health related quality of life at a small additional cost; it is relatively cost effective compared with a number of other interventions provided by the NHS.     

Calcium and Dairy Acceleration of Weight and Fat Loss during Energy Restriction in Obese Adults

Objective: Increasing 1, 25‐dihydroxyvitamin D in response to low‐calcium diets stimulates adipocyte Ca²⁺ influx and, as a consequence, stimulates lipogenesis, suppresses lipolysis, and increases lipid accumulation, whereas increasing dietary calcium inhibits these effects and markedly accelerates fat loss in mice subjected to caloric restriction. Our objective was to determine the effects of increasing dietary calcium in the face of caloric restriction in humans. Research Methods and Procedures: We performed a randomized, placebo‐controlled trial in 32 obese adults. Patients were maintained for 24 weeks on balanced deficit diets (500 kcal/d deficit) and randomized to a standard diet (400 to 500 mg of dietary calcium/d supplemented with placebo), a high‐calcium diet (standard diet supplemented with 800 mg of calcium/d), or high‐dairy diet (1200 to 1300 mg of dietary calcium/d supplemented with placebo). Results: Patients assigned to the standard diet lost 6.4 ± 2.5% of their body weight, which was increased by 26% (to 8.6 ± 1.1%) on the high‐calcium diet and 70% (to 10.9 ± 1.6% of body weight) on the high‐dairy diet (p < 0.01). Fat loss was similarly augmented by the high‐calcium and high‐dairy diets, by 38% and 64%, respectively (p < 0.01). Moreover, fat loss from the trunk region represented 19.0 ± 7.9% of total fat loss on the low‐calcium diet, and this fraction was increased to 50.1 ± 6.4% and 66.2 ± 3.0% on the high‐calcium and high‐dairy diets, respectively (p < 0.001). Discussion: Increasing dietary calcium significantly augmented weight and fat loss secondary to caloric restriction and increased the percentage of fat lost from the trunk region, whereas dairy products exerted a substantially greater effect.     

Diet quality mitigates intraspecific larval competition in Drosophila suzukii

The invasive frugivore Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) utilizes a wide range of host plants and damages important fruit crops, including blueberries, cherries, blackberries, raspberries, and strawberries. Field infestations of D. suzukii often exceed one larva per berry, suggesting that intraspecific competition may frequently occur. Because dietary resources are also likely to vary across the host range of D. suzukii, we designed a laboratory assay to measure larval performance across diets of varying quality: a standard artificial diet, a fruit‐based medium, a low‐protein, and a low‐carbohydrate diet. We manipulated egg density across these diets to provide increasing levels of competition and measured larval performance by observing survival to pupation and adulthood, and development times for both life stages. Although increasing density generally negatively impacted D. suzukii performance across diets, the magnitude of these impacts varied by diet type. Drosophila suzukii performance was generally similar in fruit and standard diets, although larval development was more rapid in fruit diets at lower densities. Even at low densities (5 or 10 eggs per arena), survival was reduced and development time increased in low‐protein diets relative to standard and fruit diets. At the two highest larval densities (20 or 40 eggs per arena), survivorship was reduced in low‐carbohydrate diets as compared to standard and fruit diets. There is evidence that larvae compensated in both low‐quality diets by extending development time, which could have consequences for population dynamics. Population models for use in D. suzukii management may need to account for both host nutritional quality and relative competition to accurately predict turnover and geographic expansion.     

The development of a synthetic diet for investigating the effects of macronutrients on the development of Plodia interpunctella

The use of chemically defined artificial diets has allowed researchers to examine questions within nutritional ecology about how macronutrients affect life‐history traits and resource‐based trade‐offs. Using a chemically defined diet, it is possible to manipulate both the total nutritional content and the ratio of macronutrients (i.e., proteins, carbohydrates, or lipids) within the diet. Studies using the geometric framework have made use of these diets to examine lifespan, fecundity, and immune responses. Here, we develop an artificial diet suitable for rearing lepidopteran larvae. We created diets with three proportions of non‐nutritive material (30, 50, and 70% indigestible cellulose) relative to protein and carbohydrate macronutrients, and compared these to standard wheat bran laboratory diet. We then examined the effects of variable nutrient content on lifespan and development time in Plodia interpunctella Hübner (Lepidoptera: Pyralidae). The artificial diets supported development (almost) as well as bran‐based laboratory diets. Total nutrient content affected development time: females that fed on the diet with the highest nutrient content took the longest time to reach eclosion. We also found evidence to support dietary restriction, with larvae receiving the fewest nutrients having the longest lifespan as adults. These findings are indicative of the usefulness of this diet as a tool to further investigate the effects of nutrient content and macronutrient imbalance on resource‐based trade‐offs and life‐history traits.     

Dietary self‐selection and rules of compromise by fifth‐instar Vanessa cardui

We examined dietary self‐selection and rules of compromise for protein (P) and digestible carbohydrate (C) intake by fifth‐instar Vanessa cardui L. (Lepidoptera: Nymphalidae: Nymphalini). We presented six fat‐free diet pairs to larvae in a choice trial to determine the ‘intake target’. In addition, we fed larvae seven fat‐free single diets differing in dietary nutrient ratio in no‐choice trials to determine the rules of compromise they exhibit when constrained to a singular, sub‐optimal dietary source. In choice trials, caterpillars regulated nutrient intake to a ratio of 1 protein to 1.09 carbohydrate (1P:1.09C), exhibiting tighter regulation of protein than of carbohydrate. Furthermore, larvae from different diet pair treatments did not differ in pupal mass or stadium duration. In no‐choice experiments, larvae reduced consumption on increasingly protein‐biased diets and increased consumption on increasingly carbohydrate‐biased diets, relative to a 1P:1C ratio diet. Differences in carbohydrate consumption were much greater between no‐choice treatments than differences in protein consumption. Dietary nutrient ratio affected pupal mass when accounting for initial larval mass. Pupal mass decreased as nutrient ratio was shifted off of 1P:1C, but to a greater extent when the ratio was skewed toward carbohydrate. Stadium duration increased as nutrient ratio diverged from 1P:1C, being more pronounced when shifted toward carbohydrate than toward protein. Regulation to near 1P:1C is consistent with results found for other Lepidoptera, and the rule of compromise exhibited by V. cardui is consistent with that expected for a generalist herbivore.     

Three-year weight change in successful weight losers who lost weight on a low-carbohydrate diet

Objective: The purpose of this study was to evaluate long‐term weight loss and eating and exercise behaviors of successful weight losers who lost weight using a low‐carbohydrate diet. Research Methods and Procedures: This study examined 3‐year changes in weight, diet, and physical activity in 891 subjects (96 low‐carbohydrate dieters and 795 others) who enrolled in the National Weight Control Registry between 1998 and 2001 and reported ≥30‐lb weight loss and ≥1 year weight loss maintenance. Results: Only 10.8% of participants reported losing weight after a low‐carbohydrate diet. At entry into the study, low‐carbohydrate diet users reported consuming more kcal/d (mean ± SD, 1895 ± 452 vs. 1398 ± 574); fewer calories in weekly physical activity (1595 ± 2499 vs. 2542 ± 2301); more calories from fat (64.0 ± 7.9% vs. 30.9 ± 13.1%), saturated fat (23.8 ± 4.1 vs. 10.5 ± 5.2), monounsaturated fat (24.4 ± 3.7 vs. 11.0 ± 5.1), and polyunsaturated fat (8.6 ± 2.7 vs. 5.5 ± 2.9); and less dietary restraint (10.8 ± 2.9 vs. 14.9 ± 3.9) compared with other Registry members. These differences persisted over time. No differences in 3‐year weight regain were observed between low‐carbohydrate dieters and other Registry members in intent‐to‐treat analyses (7.0 ± 7.1 vs. 5.7 ± 8.7 kg). Discussion: It is possible to achieve and maintain long‐term weight loss using a low‐carbohydrate diet. The long‐term health effects of weight loss associated with a high‐fat diet and low activity level merits further investigation.     

Effects of a Low‐intensity Intervention That Prescribed a Low‐carbohydrate vs. a Low‐fat Diet in Obese,Diabetic Participants

Low‐carbohydrate diets have been associated with significant reductions in weight and HbA_1c in obese, diabetic participants who received high‐intensity lifestyle modification for 6 or 12 months. This investigation sought to determine whether comparable results to those of short‐term, intensive interventions could be achieved over a 24‐month study period using a low‐intensity intervention that approximates what is feasible in outpatient practice. A total of 144 obese, diabetic participants were randomly assigned to a low‐carbohydrate diet (<30 g/day) or to a low fat diet (≤30% of calories from fat with a deficit of 500 kcal/day). Participants were provided weekly group nutrition education sessions for the first month, and monthly sessions thereafter through the end of 24 months. Weight, HbA_1c, glucose, and lipids were measured at baseline and 6, 12, and 24 months. Of the 144 enrolled participants, 68 returned for the month 24 assessment visit. Weights were retrieved from electronic medical records for an additional 57 participants (total, 125 participants) at month 24. All participants with a baseline measurement and at least one of the three other measurements were included in the mixed‐model analyses (n = 138). The low‐intensity intervention resulted in modest weight loss in both groups at month 24. At this time, participants in the low‐carbohydrate group lost 1.5 kg, compared to 0.2 kg in the low‐fat group (P = 0.147). Lipids, glycemic indexes, and dietary intake did not differ between groups at month 24 (or at months 6 or 12) (ClinicalTrials.gov number, NCT00108459).     

Glucose Metabolism and Diet Predict Changes in Adiposity and Fat Distribution in Weight‐reduced Women

Among obesity‐prone individuals, metabolic state may interact with diet in determining body composition. We tested the hypotheses that, among 103 weight‐reduced women over 1 year, (i) insulin sensitivity would be positively associated with change in %fat; (ii) this association would be modulated by dietary glycemic load (GL); and (iii) changes in fat distribution would be related to indexes of glucose metabolism. Insulin sensitivity, glucose effectiveness, fasting and postchallenge insulin and glucose, and glucose tolerance were assessed during intravenous glucose tolerance test (IVGTT). Changes in %fat and fat distribution were examined using dual‐energy X‐ray absorptiometry and computed tomography. Dietary GL was assessed on 67 women using food records. On average, women showed a +5.3 ± 3.0% change in %fat over 1 year, with the magnitude of this change being greater in relatively insulin sensitive women (+6.0 ± 0.4%, mean ± s.e.m.) than in relatively insulin resistant women (+4.4 ± 0.4 kg; P < 0.05). Women who were relatively insulin sensitive and who consumed a higher GL diet showed a +6.8 ± 0.7% change in %fat, which was greater than those who were less insulin sensitive, regardless of diet (P < 0.05), but did not differ from women who were relatively insulin sensitive and who consumed a lower GL diet (P = 0.105). Changes in intra‐abdominal and deep subcutaneous abdominal fat were inversely associated with the postchallenge decline in serum glucose. In conclusion, greater insulin sensitivity may predispose to adiposity among weight reduced women, an effect that may be ameliorated by a lower GL diet. The potential association between indexes of glucose disposal and changes in fat distribution warrants further study.     

Oligofructose Promotes Satiety in Rats Fed a High‐Fat Diet: Involvement of Glucagon‐Like Peptide‐1

Objective: To analyze the putative interest of oligofructose (OFS) in the modulation of food intake after high‐fat diet in rats and to question the relevance of the expression and secretion of intestinal peptides in that context. Research Methods and Procedures: Male Wistar rats were pretreated with standard diet or OFS‐enriched (10%) standard diet for 35 days followed by 15 days of high‐fat diet enriched or not with OFS (10%) treatment. Body weight, food intake, triglycerides, and plasma ghrelin levels were monitored during the treatment. On day 50, rats were food‐deprived 8 hours and anesthetized for blood and intestinal tissue sampling for further proglucagon mRNA, glucagon‐like peptide (GLP)‐1, and GLP‐2 quantification. Results: The addition of OFS in the diet protects against the promotion of energy intake, body weight gain, fat mass development, and serum triglyceride accumulation induced by a high‐fat diet. OFS fermentation leads to an increase in proglucagon mRNA in the cecum and the colon and in GLP‐1 and GLP‐2 contents in the proximal colon, with consequences on the portal concentration of GLP‐1 (increase). A lower ghrelin level is observed only when OFS is added to the standard diet of rats. Discussion: In rats exposed to high‐fat diet, OFS is, thus, able to modulate endogenous production of gut peptides involved in appetite and body weight regulation. Because several approaches are currently used to treat type 2 diabetes and obesity with limited effectiveness, dietary fibers such as OFS, which promote the endogenous production of gut peptides like GLP‐1, could be proposed as interesting nutrients to consider in the management of fat intake and associated metabolic disorders.     

Elevated Insulin Sensitivity in Low‐protein Offspring Rats Is Prevented by a High‐fat Diet and Is Associated With Visceral Fat

This study tests the hypothesis that a high‐fat postnatal diet increases fat mass and reduces improved insulin sensitivity (IS) found in the low‐protein model of maternal undernutrition. Offspring from Wistar dams fed either a 20% (control (CON)) or 8% (low protein (LP)) protein diet during gestation and lactation were randomly assigned to a control (con) or cafeteria (caf) diet at weaning (21 days) until 3 months of age at which point IS was measured (hyperinsulinemic–euglycemic clamp). Fat mass, growth, energy intake (EI) and expenditure (EE), fuel utilization, insulin secretion, and leptin and adiponectin levels were measured to identify a possible role in any changes in IS. IS was increased in LP‐con in comparison to CON‐con animals. Cafeteria feeding prevented this increase in LP animals but had no effect in CON animals (insulin‐stimulated glucose infusion rates (GIRs; mg/min/kg); CON‐con: 13.9 ± 1.0, CON caf: 12.1 ± 2.1, LP‐con: 25.4 ± 2.0, LP‐caf: 13.7 ± 3.7, P < 0.05). CON‐caf animals had similar percent epididymal white adipose tissue (%EWAT; CON‐con: 1.71 ± 0.09 vs. CON‐caf: 1.66 ± 0.08) and adiponectin (µg/ml: CON‐con: 4.61 ± 0.34 vs. CON‐caf: 3.67 ± 0.18) except hyperinsulinemia and relative hyperleptinemia in comparison to CON‐con. Differently, LP‐caf animals had increased %EWAT (LP‐con: 1.11 ± 0.06 vs. LP‐caf: 1.44 ± 0.08, P < 0.05) and adiponectin (µg/ml: LP‐con: 5.38 ± 0.39 vs. LP‐caf: 3.75 ± 0.35, P < 0.05) but did not show cafeteria‐induced hyperinsulinemia or relative hyperleptinemia. An increased propensity to store visceral fat in LP animals may prevent the elevated IS in LP offspring.     

Metabolic Differences in Response to a High-Fat vs. a High-Carbohydrate Diet

Energy expenditure was measured in a group of 7 subjects who received two isocaloric isonitrogenous diets for a period of 9–21 days with a 4–10-day break between diets. Diet 1 was a high-fat diet (83.5 ± 3.6% of total energy). Diet 2 was a high carbohydrate diet (83.1 ± 3.7% of total energy). Resting and postprandial resting metabolic rate were measured by open circuit indirect calorimetry 2–4 times during each metabolic period. Total energy expenditure (TEE) was measured by the doubly labeled water method over an 8–13-day period. The respiratory quotient was measured 2–4 hours after a meal during each metabolic period for the calculation of total energy expenditure by the doubly labeled water method. Levels of total T₃ (TT₃), T₃ uptake, free thyroid index and T₄ were measured at the end of each metabolic period. No significant changes in resting metabolic rate (RMR) were apparent on the two diets (1567 ± 426 kcal/d high-fat diet and 1503 ± 412 kcal/d high-carbohydrate diet n=7, p<0.15). Total energy expenditure measured in 5 subjects was significantly higher during the high-carbohydrate phase of the diet (2443 ± 422 vs. 2078 ± 482 kcal/d p<0.05). Activity estimated from TEE/RMR was greater on the high-carbohydrate diet but only approached statistical significance (p<0.06). Total T₃ was significantly lower and free thyroid index and T₃ uptake were significantly higher at the end of the high fat diet in comparison to the high-carbohydrate diet. These data suggest that individual tolerance to a high-fat diet varies considerably and may significantly lower TEE by changing levels of physical activity. The explanation for changes in thyroid hormone levels independent of changes in metabolic rate remains unclear.     

Treatment of Morbid Obesity in Inner‐City Women

Objective: To explore the use of the very‐low‐calorie formula diet (VLCD) in the indigent population of Newark, NJ, with the goal of achieving 10% weight loss within a relatively short period of 10 weeks. Research Methods and Procedures: We accepted 131 morbidly obese indigent women into our study program. The study was limited to women only and the average starting weight was 292.3 ± 5.9 lbs (± SE; 50.3 ± 0.9 body mass index [kg/m²]). We used three treatment paradigms: total cost‐free program for 10 weeks; cost‐free, but compliance requirements; and a weekly charge of $25. The results obtained were compared with two control populations: women enrolled during the same recruitment period in a comparable suburban VLCD program and a historical control population of suburban women treated from 1985 through 1995. Results: In group A (total cost‐free), 79% of patients completed the 10‐week program, but only 18% of patients achieved the goal of 10% weight loss. In group B when attendance and weight loss requirements were imposed, the dropout rate accelerated such that only 37% of patients completed the 10‐week course, and 16% of the women were successful with their weight loss. In group C, imposing $25/wk financial outlay also accelerated dropouts but had little effect on weight loss success, which was 10% of the starting group. By comparison, the suburban patients and the historical control group exhibited 67% and 76% attendance rates after 10 weeks, and 33% and 55% success rates, respectively, in achieving the weight loss goal. Discussion: We conclude that inner‐city patients exhibit great interest in weight loss when financial barriers are removed. Successful weight loss was achieved in 10% to 18% of patients using the VLCD approach, approximately one‐half of that obtained in affluent suburban women. Imposing financial or compliance restrictions to the inner‐city patients served only to enhance dropouts.     

Longitudinal Adaptations to Very Low–carbohydrate Weight‐reduction Diet in Obese Rats: Body Composition and Glucose Tolerance

Longitudinal effects of a very low–carbohydrate (VLC) and a calorie‐matched high‐carbohydrate (HC) weight reduction diet were compared in dietary obese Sprague–Dawley rats exhibiting impaired glucose tolerance and insulin resistance. Obese rats were divided into weight‐matched groups: (i) VLC rats consumed an energy‐restricted 5% carbohydrate, 60% fat diet for 8 weeks, (ii) HC rats consumed an isocaloric 60% carbohydrate, 15% fat diet, and (iii) HF rats consumed a high‐fat diet ad libitum. HC and VLC rats showed similar reductions in body fat and hepatic lipid at the midpoint of the weight‐reduction program, indicating effects due to energy deficit. At the end point, however, HC rats showed greater reductions in total and percent body fat, hepatic lipid and intramuscular lipid than did VLC rats, suggesting that diet composition induced changes in the relative efficiencies of the HC and VLC diets over time. HC rats showed marked improvement in glucose tolerance at the midpoint and end point, whereas VLC rats showed no improvement. Impaired glucose tolerance in VLC rats at the end point was due to insulin resistance and an attenuated insulin secretory response. Glucose tolerance in energy‐restricted rats correlated negatively with hepatic and intramuscular lipid levels, but not visceral or total fat mass. These findings demonstrate that adaptations to diet composition eventually enabled HC rats to lose more body fat than VLC rats even though energy intakes were equal, and suggest that the elevated levels of hepatic and intramuscular lipid associated with VLC diets might predispose to insulin resistance and impaired glucose tolerance despite weight loss.     

Variations in Body Composition and Plasma Lipids in Response to a High‐Carbohydrate Diet

Objective: To examine the extent to which variations in body composition modulate changes in the lipid profile in response to the ad libitum consumption of a diet rich in carbohydrates (CHOs) (high‐CHO diet: 58% of energy as CHOs) or high in fat and in monounsaturated fatty acids (MUFAs) (high‐MUFA diet: 40% of energy as fat, 23% as MUFAs). Research Methods and Procedures: Sixty‐three men were randomly assigned to one of the two diets that they consumed for 6 to 7 weeks. Body composition and fasting plasma lipid levels were measured at the beginning and the end of the dietary intervention. Results: The high‐CHO and high‐MUFA diets induced significant and comparable reductions in body weight and waist circumference. These changes were accompanied by significant and comparable (p < 0.01) reductions in total plasma cholesterol and low‐density lipoprotein cholesterol levels. However, the high‐MUFA diet had more beneficial effects on plasma triglyceride concentrations (p < 0.01) and on plasma high‐density lipoprotein cholesterol levels (p = 0.02) compared with the high‐CHO diet. Diet‐induced changes in waist circumference were significantly associated with changes in low‐density lipoprotein cholesterol levels in the high‐CHO group (r = 0.39, p = 0.03) but not in the high‐MUFA group (r = 0.16, p = 0.38). Discussion: Improvements in plasma lipids induced by the ad libitum consumption of a high‐CHO diet seem to be partly mediated by changes in body weight, whereas lipid changes induced by the high‐MUFA diet seem to be independent of changes in body weight.