Objectives: Although low-fat diets (LFD) have been the cornerstone of dietary guidelines for weight reduction, low-carbohydrate diets (LCD) continue to gain attention and popularity. Which diet can achieve significant and sustainable weight loss in unclear, however. Our objective in this study was to compare LCDs with LFDs and their impact on weight loss.
Methods: We performed a MEDLINE/PubMed search for English-language articles of randomized controlled studies conducted with adults who were overweight or obese for at least 6 months for the time period of January 2001-October 2014. Two reviewers independently abstracted data, including participants' characteristics, diet composition and duration, and change in weight from baseline at 6 and 12 months.
Results: A total of 17 studies were analyzed. At 6 months, the mean weight loss for participants on an LCD was -1.439 kg (95% confidence interval -2.319 to -0.558) compared with participants on an LFD (P < 0.001). At 12 months, the difference was smaller, -0.769 kg (95% confidence interval -1.361 to -0.178) but remained statistically significant (P < 0.010). The mean difference in the weight loss between the two diets was attenuated over time.
Conclusions: Reducing carbohydrate intake may help patients achieve weight loss. The mean difference in weight change between an LCD and an LFD was too small to have a meaningful impact on weight loss. More studies are needed to better elucidate the role of LCDs in weight loss efforts.