A High Fiber Diet Versus a Low-Carbohydrate Diet for Weight Loss in Obese Individuals With or Without Type 2 Diabetes
In the United States, obesity rates have climbed steadily over the years. Many different diets for weight loss have been proposed and studied, yet no one diet seems to clearly be more beneficial. Among diets that have been promoted are those high in fiber and low in carbohydrates, yet thus far, results of these studies have been mixed. Using a 2x2 complete factorial design, 173 obese men and women with or without type 2 diabetes were randomized to one of two conditions: (a) a high fiber diet (> 40 grams of fiber per day for women, >50 grams of fiber per day for men), or (b) a low carbohydrate diet (< 120 grams carbohydrate per day for both men and women). The two diets were not matched on any macronutrient nor were there any calorie restrictions. Individuals were followed for 16 weeks, upon which participants’ BMI, waist circumference, blood lipids (total, HDL, and LDL cholesterol, and triglycerides), fasting blood sugar levels, and HbAic were measured. Additionally, lipid profiles, fasting blood sugar and HbAic among those with and those without type 2 diabetes were compared. While both groups experienced weight loss, decreases in BMI, waist and hip circumferences and blood pressure, independent t tests revealed no significant differences between diets after 16 weeks with regards to these factors. Total cholesterol (mean difference between groups=9 mg/dL, p= 0.038) and LDL-C levels (mean difference between groups=7 mg/dL, p=0.045) significantly decreased amongst those on the high fiber diet when compared to those on the low-carbohydrate diet. Two-way ANOVA analyses revealed no significant differences in glucose and HbAic levels between those with diabetes when compared to those without. In conclusion, weight loss and several CVD risk factors were similar in obese subjects following a high fiber compared to a low-carbohydrate diet, while total and LDL-C levels were lower on the high fiber diet. When examining the macro- and micronutrient composition between groups, high fiber dieters consumed significantly fewer B-vitamins, whereas low-carbohydrate dieters consumed significantly more sodium, cholesterol, and total fat than those in the high fiber group. Therefore, the proatherogenic effects of a low-carbohydrate may need to be further examined in future studies.
Human and Clinical Nutrition, Preventive Medicine, Obesity -- diet therapy; Diabetes Mellitus, Type 2 -- prevention and control; Weight Loss -- physiology; Diet, Reducing -- trends; Dietary Carbohydrates -- administration and dosage; Dietary Fiber -- administration and dosage; Cross-Sectional Studies.
Networked Digital Library of Theses and Dissertations