Consumption of a 4‐Week, Carbohydrate‐Restricted Diet Improves Food Intake Motivation in Overweight Subjects
Authors: Le Nhan T , Hu Qiong , Abdul Majid Mufaqam Syed , Heimowitz Colette , Parks Elizabeth J 
Published: November 2023

BackgroundDiets high in fat and protein, and low in carbohydrate (CHO), may aid in weight loss because they reduce hunger and increase satiety. This occurs despite lower concentrations of insulin, a putative satiety hormone. However, whether such diets alter other aspects of food intake motivation, such as cognitive restraint and disinhibition, is unknown. The goal of the present study was to assess changes in food intake motivation during rapid weight loss associated with the consumption of an energy‐restricted, high‐fat, high‐protein, low‐CHO diet.MethodsNondiabetic subjects, with characteristics of the metabolic syndrome (10 males, 10 females, BMI 34 ± 3 kg/m2, age 40± 8y), were provided all food for 2 wks producing an energy deficit of 1198 ± 655 kcal/d. Dietary intake of fat was 54±4 % of energy (%E), protein, 28±2 %E, and CHO 14±1 %E. For the next 2 wks, subjects prepared their own diets to match the same food composition. Before and after the combined 4 wks of weight loss, body composition was measured by DEXA, blood biochemistries quantitated by colorimetric assays, and food intake motivation assessed using the Three Factor Eating Questionnaire (TFEQ).ResultsAfter 4 wks, body weight was reduced 3.8±0.3% (5.7±0.6kg), waist circumference 5.0±0.8% (2.2±0.3 inches), plasma TG 24±7, HDLc 10±2%, diastolic blood pressure 7.3±2.2%, and systolic blood pressure 6.2±1.4% (P<0.01, for all variables). Fasting glucose tended to be reduced from 96±2 to 91±3 mg/dL (P=0.054), and insulin fell significantly from 14±1 to 9±1 μU/L (P<0.001). With respect to food intake motivation, cognitive restraint increased from 6±1 to 12±1, hunger was reduced from 6±1 to 5±1, and disinhibition was reduced from 10±1 to 8±1 (P<0.02, for all variables). As shown in figure 1A below, the reduction in hunger tended to be associated with a significant reduction in insulin concentration (r=0.44, P=0.08). Similarly, figure 1B demonstrates a significant association between the reduction in disinhibition and the drop in insulin (r=0.78, P=0.0002).DiscussionThese results suggest 1) that any loss of satiety due to lower insulin concentrations, is balanced by a reduction in hunger on the high‐fat diet, and 2) that these two responses are biologically related in some manner such that those subjects who responded to the diet with a greater reduction in insulin were the same individuals who experienced the greatest reductions in hunger. Further, whether the correlation between reduced disinhibition and insulin is causal, or whether these concurrent reductions are driven by a third variable, is unknown.ImplicationsFuture studies should investigate whether complete provision of food, and strict dietary control, contribute directly to reduce hunger and disinhibition in overweight subjects. A better understanding of food intake motivation will aid in the design of strategies to help individuals to manage their body weights.Support or Funding InformationAtkins Nutritionals Inc.