Effects of Low-Carbohydrate vs Low-Fat Diets on Weight Loss and Cardiovascular Risk Factors

Abstract

Background: Low-carbohydrate diets have become increasingly popular for weight loss. However, evidence from individual trials about benefits and risks of these diets to achieve weight loss and modify cardiovascular risk factors is preliminary. Methods: We used the Cochrane Collaboration search strategy to identify trials comparing the effects of lowcarbohydrate diets without restriction of energy intake vs low-fat diets in individuals with a body mass index (calculated as weight in kilograms divided by the square of height in meters) of at least 25. Included trials had to report changes in body weight in intention-to-treat analysis and to have a follow-up of at least 6 months. Two reviewers independently assessed trial eligibility and quality of randomized controlled trials. Results: Five trials including a total of 447 individuals fulfilled our inclusion criteria. After 6 months, individuals assigned to low-carbohydrate diets had lost more weight than individuals randomized to low-fat diets (weighted mean difference,-3.3 kg; 95% confidence interval [CI], −5.3 to −1.4 kg). This difference was no longer obvious after 12 months (weighted mean difference, −1.0 kg; 95% CI, −3.5 to 1.5 kg). There were no differences in blood pressure. Tri-glyceride and high-density lipoprotein cholesterol values changed more favorably in individuals assigned to lowcarbohydrate diets (after 6 months, for triglycerides, weighted mean difference, −22.1 mg/dL [−0.25 mmol/L]; 95% CI, −38.1 to −5.3 mg/dL [−0.43 to −0.06 mmol/L]; and for high-density lipoprotein cholesterol, weighted mean difference, 4.6 mg/dL [0.12 mmol/L]; 95% CI, 1.5-8.1 mg/dL [0.04-0.21 mmol/L]), but total cholesterol and lowdensity lipoprotein cholesterol values changed more favorably in individuals assigned to low-fat diets (weighted mean difference in low-density lipoprotein cholesterol after 6 months, 5.4 mg/dL [0.14 mmol/L]; 95% CI, 1.2-10.1 mg/dL [0.03-0.26 mmol/L]). Conclusions: Low-carbohydrate, non-energy-restricted diets appear to be at least as effective as low-fat, energyrestricted diets in inducing weight loss for up to 1 year. However, potential favorable changes in triglyceride and highdensity lipoprotein cholesterol values should be weighed against potential unfavorable changes in low-density lipoprotein cholesterol values when low-carbohydrate diets to induce weight loss are considered.

Dietary glycaemic index, glycaemic load and subsequent changes of weight and waist circumference in European men and women

“…Both low-fat highcarbohydrate diets and low-carbohydrate high-fat diets have been found to be effective strategies for weight loss in intervention studies. [43][44][45][46] In our study, when carbohydrate intake was analysed in the same regression models as used for GL, no association with weight and waist circumference change was observed. Also noteworthy, the correlation coefficient between GL and carbohydrates was 0.98, whereas it was only 0.36 between GL and GI (data not shown).…”

Islamic fasting and weight loss: a systematic review and meta-analysis

“…Ramadan fasting is a natural experiment that occurs annually for 1 month and requires specific practices, such as nocturnal consumption of food and changes in meal frequency, food quality, energy intake and sleep cycle. Different studies have reported both positive and negative effects (2003) Kassab (2003) Rahman (2004) Kassab (2004) Yucel ( Kassab (2003) Rahman (2004) Kassab (2004) Aksungar (2005) Lamine (2006) Mansi (2007) Haghdoost ( Weight loss may reduce cardiovascular morbidity and mortality and may lead to prevention of type 2 diabetes and improved control of hypertension (48)(49)(50) . At any given Husain (1987) El Ati (1995) Finch (1998) Adlouni (1998) Maislos (1998) Roky (2001) Kassab (2003) Rahman (2004) Kassab (2004) Aksungar (2005) Lamine (2006) Mansi (2007) Haghdoost ( The pooled or 'combined' mean difference was calculated by a fixed-effects model.…”

Inclusion of fish or fish oil in weight-loss diets for young adults: effects on blood lipids

“…Fall in HDL-C is usual with a low-fat diet, around or less than 30% of energy. 40,41 It seems, therefore, that LC n-3 PUFAs in combination with highquality fish proteins could be an additional means to decrease cardiovascular risk during weight loss using diets with relatively low fat content.…”