A Plant-Based High-Carbohydrate, Low-Fat Diet in Overweight Individuals in a 16-Week Randomized Clinical Trial: The Role of Carbohydrates

Nutrients. 2018 Sep 14;10(9):1302. doi: 10.3390/nu10091302.

Abstract

The effects of carbohydrates on body weight and insulin sensitivity are controversial. In this 16-week randomized clinical trial, we tested the role of a low-fat, plant-based diet on body weight, body composition and insulin resistance. As a part of this trial, we investigated the role of changes in carbohydrate intake on body composition and insulin resistance. Participants (n = 75) were randomized to follow a plant-based high-carbohydrate, low-fat (vegan) diet (n = 38) or to maintain their current diet (n = 37). Dual-energy X-ray absorptiometry was used to measure body composition. Insulin resistance was assessed with the Homeostasis Model Assessment (HOMA-IR) index. A repeated measure ANOVA model was used to test the between-group differences from baseline to 16 weeks. A linear regression model was used to test the relationship between carbohydrate intake, and body composition and insulin resistance. Weight decreased significantly in the vegan group (treatment effect -6.5 [95% CI -8.9 to -4.1] kg; Gxt, p < 0.001). Fat mass was reduced in the vegan group (treatment effect -4.3 [95% CI -5.4 to -3.2] kg; Gxt, p < 0.001). HOMA-IR was reduced significantly in the vegan group (treatment effect -1.0 [95% CI -1.2 to -0.8]; Gxt, p = 0.004). Changes in consumption of carbohydrate, as a percentage of energy, correlated negatively with changes in BMI (r = -0.53, p < 0.001), fat mass (r = -0.55, p < 0.001), volume of visceral fat (r = -0.35, p = 0.006), and HOMA (r = -0.27, p = 0.04). These associations remained significant after adjustment for energy intake. Changes in consumption of total and insoluble fiber correlated negatively with changes in BMI (r = -0.43, p < 0.001; and r = -0.46, p < 0.001, respectively), fat mass (r = -0.42, p < 0.001; and r = -0.46, p < 0.001, respectively), and volume of visceral fat (r = -0.29, p = 0.03; and r = -0.32, p = 0.01, respectively). The associations between total and insoluble fiber and changes in BMI and fat mass remained significant even after adjustment for energy intake. Increased carbohydrate and fiber intake, as part of a plant-based high-carbohydrate, low-fat diet, are associated with beneficial effects on weight, body composition, and insulin resistance.

Keywords: carbohydrates; diet; fiber; nutrition; plant-based; vegan.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adiposity
  • Adult
  • Aged
  • Biomarkers / blood
  • Blood Glucose / metabolism
  • Diet, Fat-Restricted*
  • Diet, Vegan*
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Carbohydrates / metabolism
  • Dietary Fiber / administration & dosage
  • Female
  • Humans
  • Insulin / blood
  • Insulin Resistance
  • Male
  • Middle Aged
  • Overweight / blood
  • Overweight / diagnosis
  • Overweight / diet therapy*
  • Overweight / physiopathology
  • Plant Proteins, Dietary / administration & dosage*
  • Plant Proteins, Dietary / metabolism
  • Time Factors
  • Treatment Outcome
  • Weight Loss

Substances

  • Biomarkers
  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fiber
  • Insulin
  • Plant Proteins, Dietary