The effects of a low-carbohydrate ketogenic diet and a low-fat diet on mood, hunger, and other self-reported symptoms

The effects of a low-carbohydrate diet on appetite: A randomized controlled trial

BACKGROUND AND AIMS

The relationship between dietary macronutrient composition and appetite is controversial. We examined the effects of a year-long low-carbohydrate diet compared to a low-fat diet on appetite-related hormones and self-reported change in appetite.

METHODS AND RESULTS

A total of 148 adults with a body mass index 30-45 kg/m(2), who were free of diabetes, cardiovascular disease and chronic kidney disease at baseline were randomly assigned to either a low-carbohydrate diet (carbohydrate [excluding dietary fiber]<40 g/day; N = 75) or a low-fat diet (<30% energy from fat, <7% from saturated fat; N = 73). Participants in both groups attended individual and group dietary counseling sessions where they were provided the same behavioral curriculum and advised to maintain baseline levels of physical activity. Appetite and appetite-related hormones were measured at 0, 3, 6 and 12 months of intervention. At 12 months, mean changes (95% CI) in peptide YY were -34.8 pg/mL (-41.0 to -28.6) and in the low-carbohydrate group and -44.2 pg/mL (-50.4 to -38.0) in the low-fat group (net change: 9.54 pg/mL [0.6 to 18.2]; p = 0.036). Approximately 99% of dietary effects on peptide YY are explained by differences in dietary macronutrient content. There was no difference in change in ghrelin or self-reported change in appetite between the groups.

CONCLUSIONS

A low-fat diet reduced peptide YY more than a low-carbohydrate diet. These findings suggest that satiety may be better preserved on a low-carbohydrate diet, as compared to a low fat diet.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00609271.

Very low-carbohydrate ketogenic diet before bariatric surgery: prospective evaluation of a sequential diet

BACKGROUND

We evaluated the effectiveness of a sequential diet regimen termed the obese preoperative diet (OPOD) in morbidly obese patients with and without type 2 diabetes mellitus (T2DM) scheduled for laparoscopic bariatric surgery.

METHODS

Fifty patients (body mass index 53.5 ± 8.4 kg/m(2)) scheduled for bariatric surgery, including 14 with T2DM, were prospectively enrolled and followed the OPOD regimen: a very low-calorie ketogenic diet for 10 days, followed by a very low-calorie diet for 10 days, and then a low-calorie diet for 10 days. Patients were evaluated at baseline (T0) and after 10 days (T1), 20 days (T2), and 30 days (T3).

RESULTS

Body weight, body mass index, waist circumference, and neck circumference were significantly lower at T1, T2, and T3 than at T0 in the 48 patients who completed the OPOD. Two patients discontinued the OPOD after 4-7 days. In patients with T2DM, fasting plasma glucose levels decreased significantly, enabling reduction of diabetic medications. Plasma and urine ketone levels increased at T1 but were all <1 mmol/L, and hunger decreased during the diet period.

CONCLUSIONS

OPOD, including 10 days of a VLCKD, was safe and effective in morbidly obese patients, and it seems to be promising in morbidly obese patients with and without T2DM scheduled for laparoscopic bariatric surgery.

The effect of rate of weight loss on long-term weight management: a randomised controlled trial

BACKGROUND

Guidelines recommend gradual weight loss for the treatment of obesity, indicative of a widely held opinion that weight lost rapidly is more quickly regained. We aimed to investigate the effect of the rate of weight loss on the rate of regain in obese people.

METHODS

For this two phase, randomised, non-masked, dietary intervention trial in a Melbourne metropolitan hospital, we enrolled 204 participants (51 men and 153 women) aged 18–70 years with a BMI between 30 and 45 kg/m2. During phase 1, we randomly assigned (1:1) participants with a block design (block sizes of 2, 4, and 6) to account for sex, age, and BMI, to either a 12-week rapid weight loss or a 36-week gradual programme, both aimed at 15% weight loss. We placed participants who lost 12·5% or more weight during phase 1 on a weight maintenance diet for 144 weeks (phase 2). The primary outcome was mean weight loss maintained at week 144 of phase 2. We investigated the primary outcome by both completers only and intention-to-treat analyses. This study is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12611000190909.

FINDINGS

200 participants were randomly assigned to the gradual weight loss (n=103) or rapid weight loss (n=97) programme between Aug 8, 2008, and March 9, 2010. After phase 1, 51 (50%) participants in the gradual weight loss group and 76 (81%) in the rapid weight loss group achieved 12·5% or more weight loss in the allocated time and started phase 2. At the end of phase 2, both gradual weight loss and rapid weight loss participants who completed the study (n=43 in gradual weight loss and n=61 in rapid weight loss) had regained most of their lost weight (gradual weight loss 71·2% regain, 95% CI 58·1–84·3 vs rapid weight loss 70·5%, 57·8–83·2). Intention-to-treat analysis showed similar results (gradual weight loss 76·3% regain, 95% CI 65·2–87·4 vs rapid weight loss 76·3%, 65·8–86·8). In phase 1, one participant in the rapid weight loss group developed cholecystitis, requiring cholecystectomy. In phase 2, two participants in the rapid weight loss group developed cancer.

INTERPRETATION

The rate of weight loss does not affect the proportion of weight regained within 144 weeks. These findings are not consistent with present dietary guidelines which recommend gradual over rapid weight loss, based on the belief that rapid weight loss is more quickly regained.

FUNDING

The Australian National Health and Medical Research Council and the Sir Edward Dunlop Medical Research Foundation.

Short-term overeating results in incomplete energy intake compensation regardless of energy density or macronutrient composition

OBJECTIVE

To evaluate the effects of overeating (140% of energy requirements) a high-fat low-energy density diet (HF/LED, 1.05 kcal/g), high-fat high-energy density diet (HF/HED, 1.60 kcal/g), and high-carbohydrate (HC) LED (1.05 kcal/g) for 2-days on subsequent 4-day energy intake (EI), activity levels, appetite, and mood.

DESIGN AND METHODS

Using a randomized cross-over design, energy expenditure and EI were standardized during overeating.

RESULTS

In 20 adults with a mean ± SD BMI of 30.7 ± 4.6 kg/m(2) , EI was not suppressed until the second day after overeating and accounted for ∼30% of the excess EI. Reductions in EI did not differ among the three diets or across days. Overeating had no effect on subsequent energy expenditure but steps/day decreased after the HC/LED and HF/HED. Sleep time was increased after the HF/HED compared to both LEDs. After overeating a HF/HED vs. HF/LED, carbohydrate cravings, hunger, prospective food consumption, and sadness increased and satisfaction, relaxation, and tranquility decreased.

CONCLUSIONS

Diet type, time, or their interaction had no impact on compensation over 4 days. No adaptive thermogenesis was observed. The HF/HED vs. HF/LED had detrimental effects on food cravings, appetite, and mood. These results suggest short-term overeating is associated with incomplete compensation.

Ketogenic diets for weight loss: A review of their principles, safety and efficacy

SUMMARY

Low-carbohydrate "ketogenic" diets have increased in popularity over recent years as a means of weight loss. Published studies of these diets have been highly heterogeneous, and it remains unclear to what degree dietary carbohydrate intake must be restricted in order to induce ketosis. Despite concern that they are often relatively high in fat, ketogenic low-carbohydrate diets have been generally shown to compare favourably with low-fat diets in terms of weight loss and improvements in triglyceride and high-density lipoprotein levels. This review includes a brief overview of ketone body metabolism, and summarises the literature regarding the safety and efficacy of ketogenic diets for weight loss.:

Effects of low carbohydrate diets on energy and nitrogen balance and body composition in rats depend on dietary protein-to-energy ratio

OBJECTIVES

Truly ketogenic rodent diets are low in carbohydrates but also low in protein. The aim of this study was to differentiate effects of ketosis, low carbohydrate (LC) and/or low-protein intake on energy and nitrogen metabolism.

METHODS

We studied the nitrogen balance of rats fed LC diets with varying protein contents: LC diets consisted of 75/10, 65/20 and 55/30 percent of fat to protein (dry matter), respectively, and were iso-energetically pair-fed to a control (chow) diet to 12-wk-old male Wistar rats (n = 6 per diet). Previous studies demonstrated only LC75/10 was truly ketogenic. Food, fecal, and urine samples, as well as carcasses were collected and analyzed for heat of combustion and nitrogen (Kjeldahl method). Blood samples were analyzed for plasma protein, albumin, and triacylglycerol.

RESULTS

All LC groups displayed less body weight gain, and the degree of reduction was inversely related to digestible crude protein intake (daily weight gain compared with chow: LC75/10: -50%; LC55/30: -20%). Nitrogen excretion by urine was related to digestible protein intake (chow: 0.23 ± 0.02 g nitrogen/d; LC75/10: 0.05 ± 0.01 g nitrogen/d). Renal energy excretion was closely associated with intake of digestible crude protein (r = 0.697) and renal nitrogen excretion (r = 0.769). Energy-to-nitrogen ratio in urine was nearly doubled with LC75/10 compared with all other groups. Total body protein was highest with chow and lowest with LC75/10. Rats fed with LC75/10 displayed features of protein deficiency (reduced growth and nitrogen balance, hypoproteinemia, depletion of body protein, and increased body and liver fat), whereas the effects with the non-ketogenic diets LC65/20 and LC55/30 were less pronounced.

CONCLUSION

These results suggest that truly ketogenic LC diets in growing rats are LC diets that are also deficient in protein for growth.

Ketogenic diet does not affect strength performance in elite artistic gymnasts

BACKGROUND

Despite the increasing use of very low carbohydrate ketogenic diets (VLCKD) in weight control and management of the metabolic syndrome there is a paucity of research about effects of VLCKD on sport performance. Ketogenic diets may be useful in sports that include weight class divisions and the aim of our study was to investigate the influence of VLCKD on explosive strength performance.

METHODS

8 athletes, elite artistic gymnasts (age 20.9 ± 5.5 yrs) were recruited. We analyzed body composition and various performance aspects (hanging straight leg raise, ground push up, parallel bar dips, pull up, squat jump, countermovement jump, 30 sec continuous jumps) before and after 30 days of a modified ketogenic diet. The diet was based on green vegetables, olive oil, fish and meat plus dishes composed of high quality protein and virtually zero carbohydrates, but which mimicked their taste, with the addition of some herbal extracts. During the VLCKD the athletes performed the normal training program. After three months the same protocol, tests were performed before and after 30 days of the athletes' usual diet (a typically western diet, WD). A one-way Anova for repeated measurements was used.

RESULTS

No significant differences were detected between VLCKD and WD in all strength tests. Significant differences were found in body weight and body composition: after VLCKD there was a decrease in body weight (from 69.6 ± 7.3 Kg to 68.0 ± 7.5 Kg) and fat mass (from 5.3 ± 1.3 Kg to 3.4 ± 0.8 Kg p < 0.001) with a non-significant increase in muscle mass.

CONCLUSIONS

Despite concerns of coaches and doctors about the possible detrimental effects of low carbohydrate diets on athletic performance and the well known importance of carbohydrates there are no data about VLCKD and strength performance. The undeniable and sudden effect of VLCKD on fat loss may be useful for those athletes who compete in sports based on weight class. We have demonstrated that using VLCKD for a relatively short time period (i.e. 30 days) can decrease body weight and body fat without negative effects on strength performance in high level athletes.

Oral 28-day and developmental toxicity studies of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate

(R)-3-Hydroxybutyl (R)-3-hydroxybutyrate (ketone monoester) has been developed as an oral source of ketones, which may be utilized for energy. In a 28-day toxicity study, Crl:WI (Wistar) rats received diets containing, as 30% of the calories, ketone monoester (12 and 15 g/kg body weight/day for male and female rats, respectively). Control groups received either carbohydrate- or fat-based diets. Rats in the test group consumed less feed and gained less weight than control animals; similar findings have been documented in studies of ketogenic diets. Between-group differences were noted in selected hematology, coagulation, and serum chemistry parameters; however, values were within normal physiological ranges and/or were not accompanied by other changes indicative of toxicity. Upon gross and microscopic evaluation, there were no findings associated with the ketone monoester. In a developmental toxicity study, pregnant Crl:WI (Han) rats were administered 2g/kg body weight/day ketone monoester or water (control) via gavage on days 6 through 20 of gestation. No Caesarean-sectioning or litter parameters were affected by the test article. The overall incidence of fetal alterations was higher in the test group; however, there were no specific alterations attributable to the test substance. The results of these studies support the safety of ketone monoester.

Weight loss and improvements in fatigue in systemic lupus erythematosus: a controlled trial of a low glycaemic index diet versus a calorie restricted diet in patients treated with corticosteroids

Background: Patients with systemic lupus erythematosus (SLE) may require prolonged periods of corticosteroid therapy which lead to excessive weight gain and increased cardiovascular risk. Objective: To assess the utility of a low glycaemic index diet in patients with corticosteroid dependent SLE in achieving weight loss and improving glycaemic control. Design: A total of 23 women were enrolled in a 6 week study. All had mild, stable SLE, were receiving corticosteroids and had a body mass index > 25 kg/m2. Subjects were randomly assigned to a low glycaemic index (Low GI) diet or a calorie restricted (Low Cal) diet. The primary end point was weight loss. Secondary end points included tolerability of diet, bio-markers of cardiovascular risk, disease activity, fatigue and sleep quality. Results: Weight loss in both treatment groups was significant (mean ± SD: Low GI diet 3.9 ± 0.9 kg; Low Cal diet 2.4 ± 2.2 kg, p < 0.01 from baseline in each group). There were also significant improvements in waist and hip measurements. However, the difference in weight loss and waist and hip measurements between the two diet groups was not statistically significant. There was a statistically significant reduction in Fatigue Severity Scale in both diet groups, ( p < 0.03). Both Low GI and Low Cal diets were well tolerated, resulting in no serious adverse effects or increase in disease activity. Conclusion: Significant weight loss is achievable over 6 weeks in a diet-specific trial in subjects with stable SLE, who are on low dose prednisolone. Both diets were equally tolerable, and did not cause flares in disease activity. Our results suggest that dietary manipulation may significantly improve fatigue in subjects with SLE.

The nervous system and metabolic dysregulation: emerging evidence converges on ketogenic diet therapy

A link between metabolism and brain function is clear. Since ancient times, epileptic seizures were noted as treatable with fasting, and historical observations of the therapeutic benefits of fasting on epilepsy were confirmed nearly 100 years ago. Shortly thereafter a high fat, low-carbohydrate ketogenic diet (KD) debuted as a therapy to reduce seizures. This strict regimen could mimic the metabolic effects of fasting while allowing adequate caloric intake for ongoing energy demands. Today, KD therapy, which forces predominantly ketone-based rather than glucose-based metabolism, is now well-established as highly successful in reducing seizures. Cellular metabolic dysfunction in the nervous system has been recognized as existing side-by-side with nervous system disorders – although often with much less obvious cause-and-effect as the relationship between fasting and seizures. Rekindled interest in metabolic and dietary therapies for brain disorders complements new insight into their mechanisms and broader implications. Here we describe the emerging relationship between a KD and adenosine as a way to reset brain metabolism and neuronal activity and disrupt a cycle of dysfunction. We also provide an overview of the effects of a KD on cognition and recent data on the effects of a KD on pain, and explore the relative time course quantified among hallmark metabolic changes, altered neuron function and altered animal behavior assessed after diet administration. We predict continued applications of metabolic therapies in treating dysfunction including and beyond the nervous system.

Effect of ketogenic Mediterranean diet with phytoextracts and low carbohydrates/high-protein meals on weight, cardiovascular risk factors, body composition and diet compliance in Italian council employees

Background

There has been increased interest in recent years in very low carbohydrate ketogenic diets (VLCKD) that, even though they are much discussed and often opposed, have undoubtedly been shown to be effective, at least in the short to medium term, as a tool to tackle obesity, hyperlipidemia and some cardiovascular risk factors. For this reason the ketogenic diet represents an interesting option but unfortunately suffers from a low compliance. The aim of this pilot study is to ascertain the safety and effects of a modified ketogenic diet that utilizes ingredients which are low in carbohydrates but are formulated to simulate its aspect and taste and also contain phytoextracts to add beneficial effects of important vegetable components.

Methods

The study group consisted of 106 Rome council employees with a body mass index of ≥ 25, age between 18 and 65 years (19 male and 87 female; mean age 48.49 ± 10.3). We investigated the effects of a modified ketogenic diet based on green vegetables, olive oil, fish and meat plus dishes composed of high quality protein and virtually zero carbohydrate but which mimic their taste, with the addition of some herbal extracts (KEMEPHY ketogenic Mediterranean with phytoextracts). Calories in the diet were unlimited. Measurements were taken before and after 6 weeks of diet.

Results

There were no significant changes in BUN, ALT, AST, GGT and blood creatinine. We detected a significant (p < 0.0001) reduction in BMI (31.45 Kg/m² to 29.01 Kg/m²), body weight (86.15 kg to 79.43 Kg), percentage of fat mass (41.24% to 34.99%), waist circumference (106.56 cm to 97.10 cm), total cholesterol (204 mg/dl to 181 mg/dl), LDLc (150 mg/dl to 136 mg/dl), triglycerides (119 mg/dl to 93 mg/dl) and blood glucose (96 mg/dl to 91 mg/dl). There was a significant (p < 0.0001) increase in HDLc (46 mg/dl to 52 mg/dl).

Conclusions

The KEMEPHY diet lead to weight reduction, improvements in cardiovascular risk markers, reduction in waist circumference and showed good compliance.

Change in food cravings, food preferences, and appetite during a low-carbohydrate and low-fat diet

The study objective was to evaluate the effect of prescribing a low-carbohydrate diet (LCD) and a low-fat diet (LFD) on food cravings, food preferences, and appetite. Obese adults were randomly assigned to a LCD (n = 134) or a LFD (n = 136) for 2 years. Cravings for specific types of foods (sweets, high-fats, fast-food fats, and carbohydrates/starches); preferences for high-sugar, high-carbohydrate, and low-carbohydrate/high-protein foods; and appetite were measured during the trial and evaluated during this secondary analysis of trial data. Differences between the LCD and LFD on change in outcome variables were examined with mixed linear models. Compared to the LFD, the LCD had significantly larger decreases in cravings for carbohydrates/starches and preferences for high-carbohydrate and high-sugar foods. The LCD group reported being less bothered by hunger compared to the LFD group. Compared to the LCD group, the LFD group had significantly larger decreases in cravings for high-fat foods and preference for low-carbohydrate/high-protein foods. Men had larger decreases in appetite ratings compared to women. Prescription of diets that promoted restriction of specific types of foods resulted in decreased cravings and preferences for the foods that were targeted for restriction. The results also indicate that the LCD group was less bothered by hunger compared to the LFD group and that men had larger reductions in appetite compared to women.

Breath acetone concentration; biological variability and the influence of diet

Previous measurements of acetone concentrations in the exhaled breath of healthy individuals and the small amount of comparable data for individuals suffering from diabetes are briefly reviewed as a prelude to the presentation of new data on the sporadic and wide variations of breath acetone that occur in ostensibly healthy individuals. Data are also presented which show that following a ketogenic diet taken by eight healthy individuals their breath acetone concentrations increased up to five times over the subsequent 6 h. Similarly, the breath acetone increased six and nine times when a low carbohydrate diet was taken by two volunteers and remained high for the several days for which the diet was continued. These new data, together with the previous data, clearly indicate that diet and natural intra-individual biological and diurnal variability result in wide variations in breath acetone concentration. This places an uncertainty in the use of breath acetone alone to monitor blood glucose and glycaemic control, except and unless the individual acts as their own control and is cognizant of the need for dietary control.

Why doesn't the brain lose weight, when obese people diet?

OBJECTIVE

As has been shown recently, obesity is associated with brain volume deficits. We here used an interventional study design to investigate whether the brain shrinks after caloric restriction in obesity. To elucidate mechanisms of neuroprotection we assessed brain-pull competence, i.e. the brain's ability to properly demand energy from the body.

METHODS

In 52 normal-weight and 42 obese women (before and after ≈10% weight loss) organ masses of brain, liver and kidneys (magnetic resonance imaging), fat (air displacement plethysmography) and muscle mass (dual-energy X-ray absorptiometry) were assessed. Body metabolism was measured by indirect calorimetry. To investigate how energy is allocated between brain and body, we used reference data obtained in the field of comparative biology. We calculated the distance between each woman and a reference mammal of comparable size in a brain-body plot and named the distance 'encephalic measure'. To elucidate how the brain protects its mass, we measured fasting insulin, since 'cerebral insulin suppression' has been shown to function as a brain-pull mechanism.

RESULTS

Brain mass was equal in normal-weight and obese women (1,441.8 ± 14.6 vs. 1,479.2 ± 12.8 g; n.s.) and was unaffected by weight loss (1,483.8 ± 12.7 g; n.s.). In contrast, masses of muscle, fat, liver and kidneys decreased by 3-18% after weight loss (all p < 0.05). The encephalic measure was lower in obese than normal-weight women (5.8 ± 0.1 vs. 7.4 ± 0.1; p < 0.001). Weight loss increased the encephalic measure to 6.3 ± 0.1 (p < 0.001). Insulin concentrations were inversely related to the encephalic measure (r = -0.382; p < 0.001).

CONCLUSION

Brain mass is normal in obese women and is protected during caloric restriction. Our data suggest that neuroprotection during caloric restriction is mediated by a competent brain-pull exerting cerebral insulin suppression.

Resistance training in overweight women on a ketogenic diet conserved lean body mass while reducing body fat

BACKGROUND

The aim of the present study was to compare the effects of 10 weeks resistance training in combination with either a regular diet (Ex) or a low carbohydrate, ketogenic diet (Lc+Ex) in overweight women on body weight and body composition.

METHODS

18 untrained women between 20 and 40 years with BMI >/= 25 kg*m-2 were randomly assigned into the Ex or Lc+Ex group. Both groups performed 60-100 min of varied resistance exercise twice weekly. Dietary estimates were based on two 4-day weighed records. Body composition was estimated using Dual Energy X-ray Absorptiometry. Fasting blood samples were analyzed for total-, HDL- and LDL-cholesterol, triacylglycerols, and glucose.

RESULTS

16 subjects were included in the analyses. Percentage of energy (En%) from carbohydrates, fat and protein was 6, 66, and 22 respectively in the (Lc+Ex) group and 41, 34, 17 in the Ex group. Mean weight change (pre-post) was -5.6 +/- 2.6 kg in Lc+Ex; (p < 0.001) and 0.8 +/- 1.5 kg in Ex; (p = 0.175). The Lc+Ex group lost 5.6 +/- 2.9 kg of fat mass (p = 0.001) with no significant change in lean body mass (LBM), while the Ex group gained 1.6 +/- 1.8 kg of LBM (p = 0.045) with no significant change in fat mass (p = 0.059). Fasting blood lipids and blood glucose were not significantly affected by the interventions.

CONCLUSION

Resistance exercise in combination with a ketogenic diet may reduce body fat without significantly changing LBM, while resistance exercise on a regular diet may increase LBM in without significantly affecting fat mass. Fasting blood lipids do not seem to be negatively influenced by the combination of resistance exercise and a low carbohydrate diet.

Trends and correlates in meat consumption patterns in the US adult population

OBJECTIVE

Few studies have examined recent shifts in meat consumption (MC), differences among US population groups, and the influence of psychosocial-behavioural factors.

DESIGN

Nationally representative data collected for US adults aged >or=18 years in the 1988-1994 and 1999-2004 National Health and Nutrition Examination Survey (NHANES) and the 1994-1996 Continuing Survey of Food Intakes by Individuals (CSFII) and Diet and Health Knowledge Survey (DHKS) were used.

RESULTS

We found a U-shaped trend in MC, a decrease between 1988-1994 and 1994-1996, and an increase from 1994-1996 to 1999-2004. NHANES 1988-1994 and 1999-2004 indicate that MC did not change significantly, particularly for all meat, red meat, poultry and seafood. Between 1994-1996 and 1999-2004, average MC, including red meat, poultry, seafood and other meat products, increased in men. Women's total MC decreased, mainly due to decreased red meat and other meat products, except for increased seafood. Noticeable differences existed in the changes across population groups. Black men had the largest increase in consumption of total meat, poultry and seafood; Mexican American men had the smallest increase in poultry, seafood and other meat products. In 1999-2004, ethnic differences in MC became greater in women than among women in 1994-1996. Associations between MC and energy intake changed over time. Perceived benefit of dietary quality and food label use were associated with reduced red MC.

CONCLUSIONS

Noticeable differences exist in the shifts in MC across population groups and surveys. MC increased in men but decreased in women in recent years.

Effects and clinical potential of very-low-calorie diets (VLCDs) in type 2 diabetes

A recent study has shown that obese patients with newly diagnosed type 2 diabetes who lose 10% of their body weight are more likely to achieve glycaemic and blood pressure targets, despite weight regain. A well-established non-surgical method for achieving weight loss >or=10% within 3 months is the use of very-low-calorie diets (VLCDs). In patients with diabetes, VLCDs are associated with rapid improvement in glycaemia and cardiovascular risk factors. The present review analyses the evidence from available trials on the effects of VLCDs on body weight, glycaemic control and complications, and their potential for clinical use in diabetes management.

Low-carbohydrate diet disrupts the association between insulin resistance and weight gain

The cornerstone to treat metabolic syndrome and insulin resistance is dietary intervention. Both low-carbohydrate diet (LCD) and low-fat diet (LFD) have been reported to induce weight loss and improve these conditions. One of the factors associated with a subject's adherence to the diet is satiety. The aim of this study was to evaluate the effects of LCD and LFD on body weight, appetite hormones, and insulin resistance. Twenty guinea pigs were randomly assigned to LCD or LFD (60%:10%:30% or 20%:55%:25% of energy from fat/carbohydrate/protein, respectively) for 12 weeks. Weight and food intake were recorded every week. After this period, animals were killed and plasma was obtained to measure plasma glucose and insulin, appetite hormones, and ketone bodies. Guinea pigs fed LCD gained more weight than those fed LFD. The daily amount of food intake in grams was not different between groups, suggesting that food density and gastric distension played a role in satiety. There was no difference in leptin levels, which excludes the hypothesis of leptin resistance in the LCD group. However, plasma glucagon-like peptide-1 was 47.1% lower in animals fed LCD (P < .05). Plasma glucose, plasma insulin, and insulin sensitivity were not different between groups. However, the heavier animals that were fed LFD had impairment in insulin sensitivity, which was not observed in those fed LCD. These findings suggest that satiety was dependent on the amount of food ingested. The weight gain in animals fed LCD may be related to their greater caloric intake, lower levels of glucagon-like peptide-1, and higher protein consumption. The adoption of LCD promotes a unique metabolic state that prevents insulin resistance, even in guinea pigs that gained more weight. The association between weight gain and insulin resistance seems to be dependent on high carbohydrate intake.

Effects of two energy-restricted diets differing in the carbohydrate/protein ratio on weight loss and oxidative changes of obese men

INTRODUCTION

Low-carbohydrate, high-protein diets are a current challenge in the nutritional treatment of obesity.

OBJECTIVE

To compare the effect of a low-carbohydrate high-protein diet with a traditional hypocaloric diet on weight loss and mitochondrial oxidative metabolism.

SUBJECTS AND METHODS

Nineteen obese men (age 36+/-6 years; body mass index 34+/-2 kg/m2) were randomized to follow one of the two diets-control diet (15% protein; 30% lipids; 55% carbohydrates) or high-protein diet (30% protein; 30% lipids; 40% carbohydrates)-over an 8-week period. Anthropometry, biochemical variables, resting energy expenditure and mitochondrial oxidation were measured at the start and at the end of the intervention.

RESULTS

The high-protein diet produced a greater weight loss (-8.3+/-1.2% versus -5.5+/-2.5%, P = 0.012) than the control diet. Interestingly, an activation in the mitochondrial oxidation was found in the high-protein-fed group. This stimulation was positively correlated with the final resting energy expenditure and negatively associated with the final fat mass content.

CONCLUSION

Low-carbohydrate high-protein diets could involve specific changes in mitochondrial oxidation that could be related to a higher weight loss.

Long-term effects of provided low and high glycemic load low energy diets on mood and cognition

Energy-restricted low glycemic load diets are being used increasingly for weight loss. However, the long-term effects of such regimens on mood and cognitive performance are not known. We assessed the effects of low glycemic load (LG) and high glycemic load (HG) energy-restricted diets on mood and cognitive performance during 6 months of a randomized controlled trial when all food was provided. Subjects were 42 healthy overweight adults (age 35+/-5 years; BMI 27.8+/-1.6 kg/m(2)) with a mean weight loss of 8.7+/-5.0% that did not differ significantly by diet randomization. Mood was assessed by using the Profile of Mood States (POMS) questionnaire. Cognitive performance was assessed by using computerized tests of simple reaction time, vigilance, learning, short-term memory and attention, and language-based logical reasoning. Worsening mood outcome over time was observed in the HG diet group compared to the LG for the depression subscale of POMS (p=0.009 after including hunger as a covariate). There was no significant change over time in any cognitive performance values. These findings suggest a negative effect of an HG weight loss diet on sub-clinical depression but, in contrast to a previous suggestion, provide no support for differential effects of LG versus HD diets on cognitive performance.

Low-carbohydrate diet versus caloric restriction: effects on weight loss, hormones, and colon tumor growth in obese mice

Our objective was to compare the effects of a low-carbohydrate diet to a high-carbohydrate/calorie-restricted diet on weight loss, hormones, and transplanted colon tumor growth. Eighty male C57BL/6 mice consumed a diet-induced obesity regimen (DIO) ad libitum for 7 weeks. From Weeks 8 to 14, the mice consumed a 1) DIO diet ad libitum (HF); 2) low-carbohydrate diet ad libitum (LC); 3) high-carbohydrate diet ad libitum (HC); or 4) HC calorie restricted diet (HC-CR). MC38 cells were injected at Week 15. At the time of injection, the HC-CR group displayed the lowest body weight (25.5 +/- 0.57 g), serum insulin-like growth factor I (IGF-I; 135 +/- 56.0 ng/ml), and leptin (1.0 +/- 0.3 ng/ml) levels. This group also exhibited the longest time to palpable tumor (20.1 +/- 0.9 days). Compared to the HF group, the HC group exhibited lower body weight (39.4 +/- 1.4 vs. 32.9 +/- 0.7 g, respectively), IGF-I (604 +/- 44.2 vs. 243.4 +/- 88.9 ng/ml, respectively), and leptin (15.6 +/- 2.2 vs. 7.0 +/- 0.7 ng/ml, respectively) levels but similar tumor growth. IGF-I levels were lower in the LC group (320.0 +/- 39.9 ng/ml) than the HF group, but tumor growth did not differ. These data suggest LC diets do not slow colon tumor growth in obese mice.

Dietary electrolytes are related to mood

Dietary therapies are routinely recommended to reduce disease risk; however, there is concern they may adversely affect mood. We compared the effect on mood of a low-sodium, high-potassium diet (LNAHK) and a high-calcium diet (HC) with a moderate-sodium, high-potassium, high-calcium Dietary Approaches to Stop Hypertension (DASH)-type diet (OD). We also assessed the relationship between dietary electrolytes and cortisol, a stress hormone and marker of hypothalamic-pituitary-adrenal (HPA) axis activity. In a crossover design, subjects were randomized to two diets for 4 weeks, the OD and either LNAHK or HC, each preceded by a 2-week control diet (CD). Dietary compliance was assessed by 24 h urine collections. Mood was measured weekly by the Profile of Mood States (POMS). Saliva samples were collected to measure cortisol. The change in mood between the preceding CD and the test diet (LNAHK or HC) was compared with the change between the CD and OD. Of the thirty-eight women and fifty-six men (mean age 56.3 (sem 9.8) years) that completed the OD, forty-three completed the LNAHK and forty-eight the HC. There was a greater improvement in depression, tension, vigour and the POMS global score for the LNAHK diet compared to OD (P < 0.05). Higher cortisol levels were weakly associated with greater vigour, lower fatigue, and higher levels of urinary potassium and magnesium (r 0.1-0.2, P < 0.05 for all). In conclusion, a LNAHK diet appeared to have a positive effect on overall mood.