Weight loss on low‐fat vs. low‐carbohydrate diets by insulin resistance status among overweight adults and adults with obesity: A randomized pilot trial

Abstract

OBJECTIVE To test for differential weight loss response to Low-Fat (LF) vs. Low-Carbohydrate (LC) diets by insulin resistance status with emphasis on overall quality of both diets. METHODS Sixty-one adults, BMI 28-40 kg/m2, were randomized in a 2X2 design to LF or LC by insulin resistance status in this pilot study. Primary outcome was 6-month weight change. Participants were characterized as more insulin resistant (IR) or more insulin sensitive (IS) by median split of baseline insulin-area-under-the-curve from an oral glucose tolerance test. Intervention consisted of 14 one-hour class-based educational sessions. RESULTS Baseline % carb:% fat:% protein was 44:38:18. At 6m the LF group reported 57:21:22 and the LC group reported 22:53:25 (IR and IS combined). Six-month weight loss (kg) was 7.4 ± 6.0 (LF-IR), 10.4 ± 7.8 (LF-IS), 9.6 ± 6.6 (LC-IR), and 8.6 ± 5.6 (LC-IS). No significant main effects were detected for weight loss by diet group or IR status; no significant diet X IR interaction. Significant differences in several secondary outcomes were observed. CONCLUSION Substantial weight loss was achieved overall, but a significant diet X IR status interaction was not observed. Opportunity to detect differential response may have been limited by the focus on high diet quality for both diet groups and sample size.

Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion

“…14 However, in a recent pilot study conducted in preparation for the DIETFITS study, a significant effect modification was not detected for INS-30 status. 35 In each case in which a significant interaction was reported, investigators proposed a mechanism involving insulin secretion status, insulin sensitivity, or insulin resistance interacting with glycemic load to differentially affect weight loss response with low-fat diets high in carbohydrates vs high-fat diets low in carbohydrates. 12,36 In these studies, the consistent direction of the finding was that a lower carbohydrate diet was superior for those individuals with higher insulin secretion or higher insulin resistance; the putative mechanism involves a lower demand or burden on insulin-mediated glucose disposal for those with impaired insulin metabolism while maintaining a lower carbohydrate and higher fat diet.…”

Raised FGF-21 and Triglycerides Accompany Increased Energy Intake Driven by Protein Leverage in Lean, Healthy Individuals: A Randomised Trial

“…The increase in serum triglycerides in response to the 10% protein diet could be detrimental to health if continued over longer periods. Dietary recommendations to increase carbohydrate by increasing complex carbohydrates rather than refined sources may reduce these detrimental effects on triglycerides and HDL-cholesterol [ 46 ] observed in the case of a high carbohydrate, low fat diet [ 47 ]. Longer-term dietary studies in mice and humans show increased longevity and better metabolic health on low protein, high carbohydrate diets [ 48 – 50 ].…”

Pretreatment Fasting Plasma Glucose Modifies Dietary Weight Loss Maintenance Success: Results from a Stratified RCT

“…A total of 131 participants in the Monounsaturated Fatty Acids in Obesity study fulfilled the inclusion criteria and qualified for the 6‐month weight loss maintenance period, as they lost ≥ 8% of their initial body weight during the initial 8‐week low‐calorie diet (LCD). In this parallel‐group block (gender and initial BMI) randomized trial, participants were assigned to one of three ad libitum diets: the new Healthy Eating Pyramid, which is moderate in fat (35E%‐45E%), high in monounsaturated fatty acids (MUFA) (> 20E%), high in fiber (> 30 g/10 MJ), and high in energy density ( n = 54); the official NNR (similar to the United States Department of Agriculture Food Pyramid), which is low in fat (20E%‐30E%), high in fiber (> 30 g/10 MJ), and low in energy density ( n = 51); or the ADD (similar to the Western diet), which is high in saturated fatty acids (> 15E%), lower in fiber (< 30 g/10 MJ), and high in energy density ( n = 26). Alcohol (< 5E%) and protein (10E%‐20E%) were kept constant between the three diets.…”

“… Objective Levels of fasting plasma glucose (FPG) and fasting insulin (FI) were studied as diet‐specific prognostic markers for successful weight loss maintenance in participants with overweight. Methods After losing ≥ 8% of body weight, participants received one of three ad libitum diets for 6 months: (1) a moderate‐fat diet high in monounsaturated fatty acids (MUFA); a low‐fat, high‐fiber diet (Nordic Nutrition Recommendations [NNR]); and the Average Danish Diet (ADD). Participants were categorized as having low (< 90 mg/dL) or high (90‐105 mg/dL) FPG based on preintervention values.…”