Long-term effects of a high-protein weight-loss diet13 - Book Report/Review Example

Long-Term Effects of a High-Protein Weight-Loss Diet – Article Review & Critique Schools Number and of NameNovember 28, 2011Long-Term Effects of a High-Protein Weight-Loss Diet – Article Review & CritiqueThis paper reviews and critically analyzes the study on long-term effects of high-protein diets on weight loss, conducted by Clifton et al. (2008). The study’s limitations and areas of improvement are also discussed.1 – Background: Several studies have investigated the effects of high-protein and low-carbohydrate diets on weight loss, revealing that such diets result in a greater fat loss with very low loss of lean mass.

However, these studies were based on brief trials and hence, provide little evidence on the success of high-protein diets in maintaining long-term weight loss. Clifton et al. (2008) therefore sought to investigate the long-term effects of high-protein diets (HP) on weight loss maintenance, bone health markers and cardiovascular disease risk factors.2 – Methodology: The study was based on an intensive 12-week long weight loss program followed by a 52-week follow-up study on seventy-nine healthy women with a mean age of 49 (± 9) years.

The study was based on a parallel design in which the subjects were randomly divided into two groups, one with a high protein (HP) diet and the other with a high carbohydrate diet (HC). Body weight, BMI, plasma glucose, serum total cholesterol, insulin, C-reactive protein and other disease biomarkers were measured during the intervention and in follow-up studies. The dietary record during follow-up was based on self-reported data on food intake.3 – Result: The mean weight loss for the HP group was 4.6 ± 5.5 kg while it was 4.4 ± 6.1 kg for the HC group.

The difference in weight loss between both the groups was statistically insignificant. There was an increase in HDL cholesterol in both the groups. Variations in lipid, insulin, C-reactive protein, glucose, folate and homocysteine levels were not significantly different between the two groups. Higher levels of vitamin B-12 were found in those with the HP dietary intervention.4 – Discussion: Though the differences in weight loss between the two groups (HP and HC diets) were found to be statistically insignificant, multiple regression analysis was conducted on all subjects, collectively as one intervention group, to further ascertain the effects of HC and HP diets.

This analysis revealed that while weight loss is greater in subjects who consume higher protein diets, carbohydrate intake was a better predictor of reduction in abdominal and total fat. The reduction in disease biomarkers and risk factors was related to the beneficial effects of weight loss that resulted from a HP diet rather than the HP diet itself. While this study reveals the efficacy of HP diets in maintaining long-term weight loss, lowering disease biomarkers and increasing HDL cholesterol and vitamin B-12, some of its results contradict with the findings of earlier studies.

5 – Conclusion and sound bite: The study provides evidence that a HP diet is not only efficient in maintaining long-term weight loss but also results in a reduction in cardiovascular disease risk factors and disease biomarkers, apart from maintaining bone health. Therefore, HP diets (diets high in protein and low in saturated fat, wherein 34% of energy is derived from protein, 20% of energy is derived from fat, and 46% of energy is derived from carbohydrate) are useful in maintenance of long-term weight loss.

6 – Areas of improvement: This study was based solely on female subjects in the 20-65 age group. Therefore, it cannot be generalized to a larger population including males and children. Moreover, dietary monitoring was based on self-reported data, which is subject to bias and inaccuracy. Urinalysis of urea and creatinine reveals poor compliance with the recommended diet. Better standards should have been set to ensure that participants complied with the recommended high protein/high carbohydrate diets.

7 – Challenges to present knowledge: The results of this study contradict with the findings of several previous studies. Firstly, the findings of this study contradict with those of Krieger et al. (2006) who showed that lower carbohydrate diets are associated with greater weight loss. Moreover, it also disagrees with earlier studies that suggest that high-protein diets result in greater loss of intra-abdominal fat. This study also contrasts with earlier findings that reveal an increase in bone turnover due to weight loss, a phenomenon not observed in this study.

ReferencesClifton, P. M., Keogh, J. B. and Noakes, M. (2008). Long-term effects of a high-protein weight-loss diet. American Journal of Clinical Nutrition, 87(1), 23-29. Krieger J. W., Sitren, H.S, Daniels, M.J, and Langkamp-Henken, B. (2006). Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. American Journal of Clinical Nutrition, 83(1), 260–74.