Correspondence CSIRO, CSIRO Health Sciences and Nutrition, PO Box 10041 BC, Adelaide, SA 5000, Australia

Email peter.clifton@csiro.au

Introduction

Weight loss is important for reducing the risk of type 2 diabetes in individuals with obesity and impaired glucose homeostasis as well as improving dyslipidemia and reducing blood pressure.¹ Neither a large amount of weight loss nor weight normalization are required to achieve these effects.² Most dietary weight-loss strategies lead to reasonable weight loss at 6 months (i.e. loss of 8–10% of initial body weight), but the real challenge of treatment for obesity is long-term weight maintenance. Obese patients have an unrealistic view of the amount of weight that they can lose and this belief can have a dramatic impact on dietary intervention drop-out rates.³ There are little data on weight maintenance beyond 12 months for most dietary treatment strategies. However, any study with a follow-up period of 6 months can be considered a weight maintenance study, as weight loss stabilizes between 3 and 6 months.⁴ In this Review, short-term data on weight maintenance are discussed when 12-month data are not available, which is particularly the case for carbohydrate-restricted diets.

Serious caveats apply to all data discussed in this Review. Firstly, participants in trials of dietary therapy for obesity usually achieve better results than nontrial participants as they are more motivated and are offered greater supervision, therefore, results in clinical practice will inevitably be less favorable and more variable than those in a trial setting.¹ Secondly, high drop-out rates are observed in all studies of dietary therapies for obesity so intention-to-treat data are discussed when available.² Thirdly, there is often a 10-fold variation in weight-loss results achieved in any trial, ranging from weight gain to weight loss of over 20 kg for ostensibly the same intervention; most of this variation is related to patient compliance.³ Fourthly, data on dietary therapy for obesity are almost universally obtained from white populations.⁵ Finally, patients are invariably disappointed by the poor results of dietary treatment for obesity; however, a 5% weight loss maintained over the long term can have beneficial effects on levels of lipids and glucose.⁶

Dietary strategies for the treatment of obesity can be broadly divided into five types. Low-fat diets are focused primarily on limiting fat intake with no recommendations concerning caloric intake. Low-calorie diets reduce the amounts of all macronutrients, including fat, to achieve a daily caloric intake of 4.2–6.2 MJ. Low-calorie diets include meal-replacement diets. Very-low-calorie diets recommend a daily caloric intake of <4.2 MJ and invariably restrict fat and carbohydrate, but near normal protein intake is maintained. Carbohydrate-restricted diets specify either a modest restriction of carbohydrate and an increase in protein intake (e.g. the Zone diet or CSIRO diet) or a severe restriction of carbohydrate intake and an increase in protein and fat intake (e.g. the Atkins diet or South Beach diet). Low-glycemic-index diets mostly recommend a diet with a low glycemic load: carbohydrate intake is maintained but the type of carbohydrate consumed is changed to deliver a lower glycemic load.

Low-fat diets

Low-fat diets are probably one of the most commonly recommended diets because fat is energy-dense, poorly satiating, easy to overconsume, and fat consumption is high in developed countries where obesity rates are high. Low-fat diets are focused on restricting fat not calorie intake. This type of diet, therefore, has a lower energy density than a high-fat diet. The comparatively high volume of food intake allowed is beneficial because short-term studies have shown that human satiety is affected by the volume of food eaten rather than its weight or energy content.^{7, 8, 9} Whether continued satiety is maintained in the long term with reduced energy density diets is not known. Low-fat diets also have a high fiber content, which might also enhance satiety.¹⁰ Avenell et al.¹¹ reviewed 12 randomized controlled trials (RCTs) that investigated the effects of low-fat diets. The authors found that these diets reduced weight by an average of 5.4 kg at 12 months, and 3.6 kg for up to 3 years. However, only three studies provided data points beyond 12 months. In four of the studies, low-fat diets were associated with reduced rates of diabetes and use of antihypertensive medication for up to 3 years. There were a total of 665 individuals who received intervention and 688 controls in the analysis by Avenell and colleagues.

Astrup¹² conducted a meta-analysis of 13 studies that contained 1,728 individuals in total who were on an ad libitum low-fat diet or a control diet. A differential overall weight loss of 2.5 kg was shown for individuals on the low-fat diet (duration of trials not specified). Pre-treatment body weight was the most important determinant of response (r = 0.52) to diet, but after adjustment for this factor there was a good relationship between the reduction in the percentage dietary fat consumed and weight loss (r = 0.66). For every 1% reduction in dietary fat, a weight loss of 0.37 kg occurred, and weight loss was not related to the duration of the diet. Extrapolated to an individual with a BMI of 30 kg/m², and assuming an absolute 10% reduction in dietary fat intake, the predicted weight loss would be 4.4 kg (95% CI 2.0–6.8 kg).¹² The fact that no relationship was observed between weight loss and duration of diet suggests that a plateau occurs, and there is maintenance of the reduced weight providing that the fat restriction is adhered to.

In the Finnish Diabetes Prevention study,¹³ individuals on a diet with a below median fat intake and an above median fiber intake showed a weight loss of 3.1 kg vs 0.7 kg for those on a diet with an above median fat intake. The below median fat intake and above median fiber intake reduced the incidence of diabetes in this patient group by at least 50%.¹³ It should be noted, however, that compliance with fat intake recommendations might just be a marker of compliance to a lower energy intake and an increased exercise regime. The weight and diabetes reduction might not, therefore, be due to the reduction in fat intake per se.

Low-calorie diets

Low-calorie diets recommend a daily caloric intake of 4.2–6.7 MJ and have been compared with low-fat diets for the treatment of obesity. Pirozzo et al.¹⁴ performed a systematic review of six trials that compared low-calorie and low-fat diets. The systematic review included studies with a follow-up duration of at least 6 months after intervention (which varied from 3 to 18 months) and excluded studies that enrolled participants who had major comorbidities. A median of 106 participants were included per trial. Low-fat diets were shown to be inferior to the low-calorie diets with a weight-loss difference of 1.1 kg at 12 months (five studies analyzed) and 3.7 kg at 18 months (three studies analyzed); however, this difference was not statistically significant and the studies included in the analysis were very heterogeneous. Another study including 90 individuals has shown that a calorie-controlled diet with a moderate fat intake is superior to a low-fat diet with a weight-loss difference of nearly 4 kg over 14 months.¹⁵

Meal-replacement diets

Meal-replacement diets are a form of low-calorie diet in which one or two full calorie meals daily are replaced with a low-calorie drink or bar that usually has an energy content of no more than 1 MJ and consists most commonly of protein with a small amount of fat and carbohydrate. Commercial meal-replacement diets represent both a dietary change and a behavior modification strategy, and are popular among people trying to lose weight. Levy and Heaton¹⁶ reported that in the US, 15% of women and 13% of men who were trying to lose weight were using meal replacements as their weight-loss strategy. Six, short-term RCTs examining meal replacement as a strategy for weight loss have been evaluated in a meta-analysis.¹⁷ This analysis found that a diet plan including at least one meal replacement daily achieved greater weight loss (approximately 2.5 kg greater) at 3 months than a food-based diet plan with a reduced energy intake.¹⁷ Flecthner-Mors et al.¹⁸ performed a 3-month RCT to compare a meal-replacement diet with an energy-restricted diet in 100 obese patients. The meal-replacement group showed greater weight loss than the energy-restricted diet group. The 3-month study was followed by a nonrandomized follow-up over 48 months. At this stage, both treatment groups were advised to substitute one meal and one snack with a meal and snack replacement. At the end of the study, 75% of the original participants were available for follow-up. Weight loss was 3.2 0.8% for the energy-restricted group and 8.4 0.8% for the meal-replacement group (P <0.05). Superior weight loss in the meal-replacement group was shown to persist for up to 4 years. Calorie control with meal replacement is, therefore, superior to a calorie-controlled diet with normal foods.

In the Look AHEAD Study, a lifestyle intervention for weight loss including meal replacements was shown to result in an 8.6% reduction in body weight at 12 months in overweight and obese patients with type 2 diabetes.¹⁹ High-protein meal replacements can also lead to excellent weight loss (10.7%) in overweight and obese nondiabetic individuals at 12 months.⁴

Very-low-calorie diets

Very-low-calorie diets work on the same principal as low-calorie diets but have an even lower daily calorie intake of <4.2 MJ. Anderson and colleagues²⁰ performed a meta-analysis examining weight loss in 4,287 obese patients from the US after 24 weeks of treatment with either low-energy (low-calorie) diets (10 studies analyzed; 11.4% weight loss) or very-low-energy diets (19 studies analyzed; 21.3% weight loss). The differences in weight loss between these diets tended to become smaller in the long term (2–5 years).²⁰ Lantz et al.²¹ examined the weight loss of 113 obese patients on a very-low-calorie diet or a low-calorie diet and found that weight loss after 4 years was the same for the 55 patients who were available for follow-up at this time: 7.6 kg for the very-low-calorie diet vs 6.3 kg for the low-calorie diet.

Carbohydrate-restricted diets

There are two popular forms of carbohydrate-restricted weight-loss diets. One replaces a moderate amount of carbohydrate with protein and is low in fat, the other replaces the majority of the carbohydrate with both protein and fat (also known as a ketogenic diet). Normal protein intake is in the range 12–18% of daily energy intake. Protein intake for a carbohydrate-restricted diet might be in the range 25–35% of daily energy intake. Actual protein intake (in grams) in a weight-loss diet might not be much greater than that in a normal diet because of the restricted intake of the other macronutrients. This fact might be quite important when considering the potential adverse effects of high-protein diets.

The success of carbohydrate-restricted diets is believed to be due to the enhanced satiety provided by the increased protein compared with other macronutrients,^{22, 23} in addition to the minor benefit of increased thermogenesis.²³ Furthermore, the severe carbohydrate restriction of the Atkins diet is a simple and easy strategy for patients to follow and its simplicity might be its most powerful attribute. Calculated weight losses from ketosis resulting from a very-low-carbohydrate diet are small. However, a study of obese patients on ad libitum food intake in a metabolic ward setting has shown that a ketogenic diet blunts appetite and leads to an approximate 10% reduction in food intake compared with a high-protein, moderate-carbohydrate diet.²⁴

In a prospective, Danish study, 65 healthy, overweight or obese individuals were placed on either a high-carbohydrate (58% carbohydrate, 12% protein), or a moderate-carbohydrate, high-protein (45% carbohydrate, 25% protein) diet²² with no guidance on energy intake. All food was self-selected from a study shop. Weight loss after 6 months was 5.1 kg in the high-carbohydrate group and 8.9 kg in the high-protein group (P <0.001); fat loss was 4.3 kg and 7.6 kg, respectively (P <0.0001). No changes in weight loss occurred in the overweight and obese control group. More individuals lost >10 kg in the high-protein group (35%) than in the high-carbohydrate group (9%). Similar results were observed at 1 and 2 years: more individuals in the high-protein group lost >10 kg than in the high-carbohydrate group (17% vs 0%; P <0.09). At 24 months, both groups tended to maintain their 12-month weight loss, but more than 50% of patients were lost to follow-up.²⁵ It has yet to be determined whether a low-carbohydrate, high-protein diet can be sustained in the long term or leads to better outcomes than other weight-loss diets. The number of drop-outs in long-term weight-loss studies is a major problem, no matter how well-conducted the studies are and limits the conclusions that can be drawn.

The outcomes of studies of obese patients on low-carbohydrate and very-low-carbohydrate diets compared with other weight-loss diets are summarized in Table 1. Four studies have compared a low-carbohydrate, ketogenic diet with a low-fat diet.^{26, 27, 28, 29, 30} All the studies showed that a low-carbohydrate, ketogenic diet resulted in greater weight loss at 6 months than a low-fat diet, but there was no significant difference in weight loss at 12 months. Serum triglyceride levels were lower and HDL cholesterol levels were higher in patients on the ketogenic diet than in those on the low-fat diet, but LDL cholesterol levels were no different.

Table 1 Outcomes of obese patients on very-low-carbohydrate diets compared with other weight-loss diets for 6 months or longer.

Full tableFigures & Tables indexDownload Power Point slide (198K)

In several other studies, the comparison of either three or four different weight-loss diets, including a ketogenic diet, showed either no differences in weight loss at 12 months^{31, 32, 33} or increased weight loss with the ketogenic diet;³⁴ however, the reasons for this latter finding are not clear. A study by Shai et al.,³⁵ with excellence patient retention and adherence to the prescribed diets, showed that a low-carbohydrate, Atkins-style diet produced equivalent weight loss to a Mediterranean-style diet (4.7 kg and 4.4 kg, respectively) and was superior to the low-fat diet (2.9 kg weight loss) at 2 years. The lipid changes were similar to those noted above.³⁵

In a meta-analysis by Nordmann et al.,³⁶ five trials including 447 individuals who were followed up for at least 6 months with intention-to-treat analysis were evaluated. After 6 months, individuals assigned to low-carbohydrate diets lost more weight than those on low-fat diets (weighted mean difference -3.3 kg). This difference was no longer obvious after 12 months. Serum triglyceride levels reduced and HDL cholesterol levels increased after 6 months in individuals on a low-carbohydrate diet, but total cholesterol and LDL cholesterol decreased in patients on a low-fat diet. There was no difference in the blood pressure of patients on either diet.

Krieger et al.³⁷ examined 87 short-term, dietary weight-loss studies (some in which energy intake was restricted and others in which diet was ad libitum). The authors found that a daily protein intake of more than 1.05 g/kg of body weight was associated with an increased retention of lean tissue (mostly muscle) compared with a protein intake of 1.05 g/kg (0.6 kg difference in lean tissue retention between diets); in studies longer than 12 weeks in duration, the difference in lean tissue retention increased to 1.2 kg. Carbohydrate intake influenced weight loss; a carbohydrate intake of approximately 35–40% of the daily energy intake resulted in a 2 kg greater loss of fat mass compared with a higher level of carbohydrate intake, but this loss was accompanied by a 0.7 kg greater loss of lean tissue. In studies 12 weeks or longer in duration, this difference in loss of fat and lean tissue increased to 5.6 kg and 1.7 kg, respectively.

In a study of 100 overweight and obese women by Noakes et al.,³⁸ 50 patients with high serum triglyceride levels (>1.5 mmol/l) lost more fat mass when on a high-protein diet than the 50 patients on a high-carbohydrate diet (6.4 kg vs 3.4 kg, respectively; P = 0.035). In a 1-year follow-up, women who reported eating more than 90 g of protein daily were 3 kg lighter than women who ate less than this amount; protein intake was confirmed by determining the urinary urea:creatinine ratio.³⁹ In addition, in another study by the same group, obese individuals with type 2 diabetes were shown to have lost weight and have an improved lipid profile at 1 year follow-up after completing a 12-week high-protein diet.⁴⁰ Even short-term dietary interventions can, therefore, have a long-term favorable effect, even if some of the lost weight is regained.

Carbohydrate-restricted weight-loss diets with a modest increase in protein intake can have beneficial effects on weight and lipids compared with high-carbohydrate diets, and this benefit can persist for as long as 2 years.

Low-glycemic-index diets

A meta-analysis has examined four short-term studies on low-glycemic-index diets (in which only carbohydrate type is changed), and two studies on low-glycemic-load diets (in which both type and amount of carbohydrate is changed).⁴¹ The meta-analysis included 202 participants who were on diets of 6 weeks to 6 months duration. The analysis concluded that low-glycemic-index and low-glycemic-load diets increased weight loss by 1.1 kg (95% CI -2.0 to -0.2, P <0.05) and lowered LDL cholesterol levels by 0.24 mmol/l, compared with control diets with a high glycemic index or load. However, this analysis failed to include the majority of studies on low-glycemic-load diets; low-carbohydrate (both ketogenic and nonketogenic diets) and high-protein diets are considered low-glycemic-load diets, but these were excluded from the analysis.⁴¹

The role of micronutrients, Supplements and Herbs

There are a wide variety of supplements (nearly 50) available to assist weight loss, but data supporting their efficacy are very limited or nonexistent. Only calcium and conjugated linoleic acid have a good evidence base.

Weight maintenance

Any diet with caloric restriction can lead to weight loss, but the key question is how to maintain this weight loss in the long term. The National Weight Control Registry in the US contains the details of 4,800 individuals who have lost at least 13.6 kg and maintained this loss for at least 1 year.⁴⁷ Approximately 20% of overweight individuals are successful in achieving long-term weight loss when it is defined as losing at least 10% of initial body weight and maintaining that loss for at least 1 year.⁴⁷ Individuals in the weight-loss register maintained their body weight using a few simple strategies:⁴⁸ eating a low-fat diet of limited variety,⁴⁹ eating breakfast almost every day,⁵⁰ weighing themselves regularly (usually daily), engaging in high levels of physical activity (1 h daily),⁴⁸ watching little television,⁵¹ and maintaining a consistent food-intake pattern across week days and weekends.⁴⁹ Weight regain over 1 year was related to higher caloric intake, fast-food consumption, fat intake and reduced physical activity.⁵²

Adverse effects of dietary therapy

There is no potential risk from eating a high-fiber, high-carbohydrate weight-loss diet other than the bone and muscle loss that is seen with all weight-loss diets, but carbohydrate-restricted diets have several risks attributed to the higher protein intake as outlined below.

The addition of nondietary therapies

Caloric restriction will always lead to weight loss but better and more sustained results can be achieved with the addition of both exercise and behavioral therapy. Exercise can also lead to greater retention of muscle and an improved cardiovascular fitness. Behavioral therapy can change behaviors such as nonhungry eating, which can derail weight maintenance. When dietary therapy fails, medication and surgery are valid options.

Mortality associated with weight-loss interventions

In a systematic review, Poobalan et al.⁷¹ examined 11 papers based on eight weight-loss studies. All the studies had weight loss and mortality as outcome measures, and had a follow-up period of >2 years. Results were mixed for men, with some studies showing adverse outcomes of weight and others a positive benefit.⁷² One study indicated that overweight or obese women with obesity-related illness who had lost weight intentionally over 1 year had significantly reduced their mortality rate by 19–25%.⁷¹ A meta-analysis revealed that studies of overweight or obese patients with diabetes, irrespective of sex, showed a statistically significant benefit of intentional weight loss on mortality (hazard ratio for death 0.75 (0.67–0.83).⁷¹

Conclusions

Only 20% of individuals on dietary treatment for obesity maintain a weight loss of 10% after 3 years. The simplest and probably the most effective dietary strategy for long-term weight loss seems to be the use of meal replacements, preferably those that are high in protein, but data are limited. Strategies to maintain weight loss include eating breakfast daily, engaging in high levels of physical activity, watching little television and maintaining a consistent pattern of food intake. When dietary therapy fails, surgery offers the only reliable method of sustained weight loss with substantial reductions in comorbidities. A combination of caloric restriction plus long-acting pramlintide and leptin (to reduce hunger and craving) might prove to be a successful long-term method of weight loss, but results in individuals at 6 months follow-up⁷² show that this strategy is no better than meal replacements. Compliance is a major issue in dietary therapy but it also influences the final outcome in medical and surgical therapy, particularly gastric banding. Behavioral therapy should, therefore, be offered to all patients with significant obesity, or to overweight patients who have failed several attempts with dietary treatment.

References

1. Sjostrom L et al. (2004) Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery. N Engl J Med 351: 2683–2693 | Article | PubMed | ISI |
2. Pontiroli AE et al. (2005) Laparoscopic gastric banding prevents type 2 diabetes and arterial hypertension and induces their remission in morbid obesity: a 4-year case-controlled study. Diabetes Care 28: 2703–2709 | Article | PubMed |
3. Foster GD et al. (2001) Obese patients' perceptions of treatment outcomes and the factors that influence them. Arch Intern Med 161: 2133–2139 | Article | PubMed | ISI | ChemPort |
4. Keogh JB and Clifton P (2008) The effect of meal replacements high in glycomacropeptide on weight loss and markers of cardiovascular disease risk. Am J Clin Nutr 87: 1602–1605 | PubMed | ChemPort |
5. Alhassan S et al. (2008) Dietary adherence and weight loss success among overweight women: results from the A TO Z weight loss study. Int J Obes (Lond) 32: 985–991 | Article | PubMed | ChemPort |
6. Ditschuneit H et al. (1999) Metabolic and weight-loss effects of a long-term dietary intervention in obese patients. Am J Clin Nutr 69: 198–204 | PubMed | ChemPort |
7. Rolls BJ et al. (1998) Volume of food consumed affects satiety in men. Am J Clin Nutr 67: 1170–1177 | PubMed | ChemPort |
8. Rolls BJ et al. (2005) Changing the energy density of the diet as a strategy for weight management. J Am Diet Assoc 105 (Suppl 1): S98–S103 | Article |
9. Osterholt KM et al. (2007) Incorporation of air into a snack food reduces energy intake. Appetite 48: 351–358 | Article | PubMed |
10. Samra RA and Anderson GH (2007) Insoluble cereal fibre reduces appetite and short term food intake and glycemic response to food consumed 75 minutes later by healthy men. Am J Clin Nutr 86: 972–979 | PubMed | ChemPort |
11. Avenell A et al. (2004) What are the long-term benefits of weight reducing diets in adults? A systematic review of randomized controlled trials. J Hum Nutr Diet 17: 317–335 | Article | PubMed | ChemPort |
12. Astrup A (2001) The role of dietary fat in the prevention and treatment of obesity: efficacy and safety of low-fat diets. Int J Obes Relat Metab Disord 25 (Suppl 1): S46–S50 | Article |
13. Lindströöm J et al. (2006) High-fibre, low-fat diet predicts long-term weight loss and decreased type 2 diabetes risk: the Finnish Diabetes Prevention Study. Diabetologia 49: 912–920 | Article | PubMed | ISI | ChemPort |
14. Pirozzo S et al. (2003) Should we recommend low-fat diets for obesity. Obes Rev 4: 83–90 | Article | PubMed | ChemPort |
15. Azadbakht L et al. (2007) Better dietary adherence and weight maintenance achieved by a long-term moderate-fat diet. Br J Nutr 97: 399–404 | Article | PubMed | ChemPort |
16. Levy AS and Heaton AW (1993) Weight control practices of US adults trying to lose weight. Ann Intern Med 119: 661–666 | PubMed | ChemPort |
17. Heymsfield SB et al. (2003) Weight management using a meal replacement strategy: meta and pooling analysis from six studies. Int J Obes Relat Metab Disord 27: 537–549 | Article | PubMed | ChemPort |
18. Flechtner-Mors M et al. (2000) Metabolic and weight loss effects of long-term dietary intervention in obese patients: four-year results. Obes Res 8: 399–402 | Article | PubMed | ChemPort |
19. Look AHEAD Research Group (2007) Reduction in weight and cardiovascular disease risk factors in individuals with type 2 diabetes: one-year results of the look AHEAD trial. Diabetes Care 30: 1374–1383 | Article | PubMed |
20. Anderson JW et al. (2001) Long-term weight-loss maintenance: a meta-analysis of US studies. Am J Clin Nutr 74: 579–584 | PubMed | ISI | ChemPort |
21. Lantz H et al. (2003) A dietary and behavioural programme for the treatment of obesity: a 4-year clinical trial and a long-term post-treatment follow-up. J Intern Med 254: 272–279 | Article | PubMed | ISI |
22. Skov AR et al. (1999) Randomized trial on protein vs carbohydrate in ad libitum fat reduced diet for the treatment of obesity. Int J Obes Relat Metab Disord 23: 528–536 | Article | PubMed | ChemPort |
23. Halton TL and Hu FB (2004) The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. Am Coll Nutr 23: 373–385
24. Johnstone AM et al. (2008) Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr 87: 44–55 | PubMed | ChemPort |
25. Due A et al. (2004) Effect of normal-fat diets, either medium or high in protein, on body weight in overweight subjects: a randomised 1-year trial. Int J Obes Relat Metab Disord 28: 1283–1290 | Article | PubMed | ChemPort |
26. Foster GD et al. (2003) A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med 348: 2082–2090 | Article | PubMed | ISI | ChemPort |
27. Samaha FF et al. (2003) A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med 348: 2074–2081 | Article | PubMed | ISI | ChemPort |
28. Stern L et al. (2004) The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: one-year follow-up of a randomized trial. Ann Intern Med 140: 778–785 | PubMed | ISI |
29. Brehm BJ et al. (2003) A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. J Clin Endocrinol Metab 88: 1617–1623 | Article | PubMed | ISI | ChemPort |
30. Yancy WS Jr et al. (2004) A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia: a randomized, controlled trial. Ann Intern Med 140: 769–777 | PubMed | ISI |
31. McAuley KA et al. (2005) Comparison of high-fat and high-protein diets with a high-carbohydrate diet in insulin-resistant obese women. Diabetologia 48: 8–16 | Article | PubMed | ISI | ChemPort |
32. McAuley KA et al. (2006) Long-term effects of popular dietary approaches on weight loss and features of insulin resistance. Int J Obes (Lond) 30: 342–349 | Article | PubMed | ChemPort |
33. Dansinger ML et al. (2005) Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA 293: 43–53 | Article | PubMed | ISI | ChemPort |
34. Gardner CD et al. (2007) Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A TO Z Weight Loss Study: a randomized trial. JAMA 297: 969–977 | Article | PubMed | ISI | ChemPort |
35. Shai I et al. (2008) Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med 359: 229–241 | Article | PubMed | ChemPort |
36. Nordmann AJ et al. (2006) Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med 166: 285–293 | Article | PubMed | ISI | ChemPort |
37. Krieger JW et al. (2006) Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression 1. Am J Clin Nutr 83: 260–274 | PubMed | ChemPort |
38. Noakes M et al. (2005) Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women. Am J Clin Nutr 81: 1298–1306 | PubMed | ChemPort |
39. Clifton PM et al. (2008) Long-term effects of a high-protein weight-loss diet. Am J Clin Nutr 87: 23–29 | PubMed | ChemPort |
40. Brinkworth GD et al. (2004) Long-term effects of advice to consume a high-protein, low-fat diet, rather than a conventional weight-loss diet, in obese adults with type 2 diabetes: one-year follow-up of a randomised trial. Diabetologia 47: 1677–1686 | Article | PubMed | ISI | ChemPort |
41. Thomas DE et al. Low glycaemic index or low glycaemic load diets for overweight and obesity. Cochrane Database of Systematic Reviews 2007, Issue 3. Art. No.: CD005105. doi:10.1002/14651858.CD005105.pub2. | Article |
42. Zemel MB et al. (2000) Regulation of adiposity by dietary calcium. FASEB J 14: 1132–1138 | PubMed | ISI | ChemPort |
43. Trowman R et al. (2006) A systematic review of the effects of calcium supplementation on body weight. Br J Nutr 95: 1033–1038 | Article | PubMed | ChemPort |
44. Pittler MH and Ernst E (2004) Dietary supplements for body-weight reduction: a systematic review. Am J Clin Nutr 79: 529–536 | PubMed | ChemPort |
45. Whigham LD et al. (2007) Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr 85: 1203–1211 | PubMed | ChemPort |
46. Risérus U et al. (2004) Effects of cis-9,trans-11 conjugated linoleic acid supplementation on insulin sensitivity, lipid peroxidation, and proinflammatory markers in obese men. Am J Clin Nutr 80: 279–283 | PubMed | ISI | ChemPort |
47. Hill JO et al. (2005) The National Weight Control Registry: is it useful in helping deal with our obesity epidemic. J Nutr Educ Behav 37: 206–210 | Article | PubMed |
48. Wing RR and Phelan S (2005) Long-term weight loss maintenance. Am J Clin Nutr 82 (Suppl 1): S222–S225
49. Raynor HA et al. (2005) Amount of food group variety consumed in the diet and long-term weight loss maintenance. Obes Res 13: 883–890 | Article | PubMed |
50. Wyatt HR et al. (2002) Long-term weight loss and breakfast in subjects in the National Weight Control Registry. Obes Res 10: 78–82 | Article | PubMed |
51. Raynor DA et al. (2006) Television viewing and long-term weight maintenance: results from the national weight control registry. Obesity (Silver Spring) 14: 1816–1824 | Article | PubMed |
52. Phelan S et al. (2006) Are the eating and exercise habits of successful weight losers changing. Obesity (Silver Spring) 14: 710–716 | Article | PubMed |
53. Knight EL et al. (2003) The impact of protein intake on renal function decline in women with normal renal function or mild renal insufficiency. Ann Intern Med 138: 460–467 | PubMed |
54. Munger RG (1999) Prospective study of dietary protein intake and risk of hip fracture in postmenopausal women. Am J Clin Nutr 69: 147–152 | PubMed | ChemPort |
55. Skov AR et al. (2002) Effect of protein intake on bone mineralization during weight loss: a 6-month trial. Obes Res 10: 432–438 | Article | PubMed |
56. Larsson SC and Wolk A (2006) Meat consumption and risk of colorectal cancer: a meta-analysis of prospective studies. Int J Cancer 119: 2657–2664 | Article | PubMed | ISI | ChemPort |
57. Larsson SC and Wolk A (2007) Obesity and colon and rectal cancer risk: a meta-analysis of prospective studies. Am J Clin Nutr 86: 556–565 | PubMed | ChemPort |
58. Chaput JP et al. (2008) Increase in depression symptoms with weight loss: association with glucose homeostasis and thyroid function. Appl Physiol Nutr Metab 33: 86–92 | Article | PubMed |
59. Kaukua J et al. (2003) Health-related quality of life in obese outpatients losing weight with very-low-energy diet and behaviour modification: a 2-year follow-up study. Int J Obes Relat Metab Disord 27: 1072–1080 | Article | PubMed | ChemPort |
60. Karlsson J et al. (2007) Ten-year trends in health-related quality of life after surgical and conventional treatment for severe obesity: the SOS intervention study. Int J Obes (Lond) 31: 1248–1261 | Article | PubMed | ChemPort |
61. Sampath A et al. (2007) Kidney stones and the ketogenic diet: risk factors and prevention. J Child Neurol 22: 375–378 | Article | PubMed |
62. Tay J et al. (2008) Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects. J Am Coll Cardiol 51: 59–67 | Article | PubMed | ChemPort |
63. Shaw K et al. Exercise for overweight or obesity. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD003817. doi:10.1002/14651858.CD003817.pub3 | Article |
64. Thomas DE et al. Exercise for type 2 diabetes mellitus. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD002968. doi:10.1002/14651858.CD002968.pub2 | Article |
65. Saris WH et al. (2003) How much physical activity is enough to prevent unhealthy weight gain? Outcome of the IASO 1st Stock Conference and consensus statement. Obes Rev 4: 101–114 | Article | PubMed | ChemPort |
66. Shaw K et al. Psychological interventions for overweight or obesity. Cochrane Database of Systematic Reviews 2005, Issue 2. Art. No.: CD003818. doi:10.1002/14651858.CD003818.pub2 | Article |
67. Rucker D et al. (2007) Long term pharmacotherapy for obesity and overweight: updated meta-analysis. BMJ 335: 1194–1199 | Article | PubMed | ChemPort |
68. Maggard MA et al. (2005) Meta-analysis: surgical treatment of obesity. Ann Intern Med 142: 547–559 | PubMed | ISI |
69. Buchwald H et al. (2004) Bariatric surgery: a systematic review and meta-analysis. JAMA 292: 1724–1737 | Article | PubMed | ISI | ChemPort |
70. Sjöström L et al. for the Swedish Obese Subjects Study (2007) Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med 357: 741–752 | Article | PubMed |
71. Poobalan AS et al. (2007) Long-term weight loss effects on all cause mortality in overweight/obese populations. Obes Rev 8: 503–513 | Article | PubMed | ChemPort |
72. Roth JD et al. (2008) Leptin responsiveness restored by amylin agonism in diet-induced obesity: evidence from nonclinical and clinical studies. Proc Natl Acad Sci USA 105: 7257–7262 | Article | PubMed |

Contact the journal about this article

Subject areas under which this article appears: Nutrition