Low-Carbohydrate Diet Macronutrient Quality and Weight Change

Abstract

ImportanceThe associations of low-carbohydrate diets (LCDs) with long-term weight management remains unclear, and the source and quality of macronutrients within LCDs are less explored.ObjectivesTo prospectively examine associations between changes in LCD indices and weight change among US adults.Design, Setting, and ParticipantsThis prospective cohort study included initially healthy participants at baseline from the Nurses’ Health Study (NHS; 1986-2010), Nurses’ Health Study II (NHSII; 1991-2015), and Health Professionals Follow-up Study (HPFS; 1986-2018). Data analysis was performed between November 2022 and April 2023.ExposuresFive LCD indices were examined: (1) a total LCD (TLCD) emphasizing overall lower carbohydrate intake; (2) an animal-based LCD (ALCD) that emphasized animal-sourced protein and fat; (3) a vegetable-based LCD (VLCD) that emphasized plant-sourced protein and fat; (4) a healthy LCD (HLCD) emphasizing less refined carbohydrates, more plant protein, and healthy fat; and (5) an unhealthy LCD (ULCD) emphasizing less healthful carbohydrates, more animal protein, and unhealthy fat.Main Outcomes and MeasuresThe outcome of interest was 4-year changes in self-reported body weight.ResultsA total of 123 332 participants (mean [SD] age, 45.0 [9.7] years; 103 320 [83.8%] female) were included in this study. The median carbohydrate intake (as a percentage of energy) of the highest quintiles of TLCD score at baseline ranged from 38.3% in HPFS to 40.9% in NHSII. Mean weight gain over 4-year intervals among participants varied from 0.8 kg in the HPFS to 1.8 kg in the NHSII. After adjusting for demographics and baseline and concomitant changes of selected lifestyle factors, each 1-SD increase in TLCD score was associated with 0.06 (95% CI, 0.04-0.08) kg more weight gain over the 4-year periods. Similarly, participants gained 0.13 (95% CI, 0.11 to 0.14) kg per each 1-SD increase in ALCD score and 0.39 (95% CI, 0.37 to 0.40) kg per each 1-SD change in ULCD score. In contrast, each 1-SD increase in VLCD score was associated with 0.03 (95% CI, 0.01 to 0.04) kg less weight gain, and each 1-SD increase in HLCD score was associated with 0.36 (95% CI, 0.35 to 0.38) kg less weight gain. The associations were more pronounced among obese individuals (per 1-SD increase in HLCD score: BMI ≥30, 0.88 [95% CI, 0.80, 0.97] kg less weight gain; BMI <25, 0.23 [95% CI, 0.20, 0.26] kg less weight gain; P for interaction < .001).Conclusions and RelevanceThese findings suggest that the quality of LCDs may play a critical role in modulating long-term weight change. Only LCDs that emphasized high-quality protein, fat, and carbohydrates from whole grains and other plant-based foods were associated with less weight gain.

Longitudinal Relationship between the Percentage of Energy Intake from Macronutrients and Overweight/Obesity among Chinese Adults from 1991 to 2018

“…In a study in the United States, increased daily consumption of refined grains and starchy vegetables was found to be associated with long-term weight gain, whereas increased intake of whole grains, fruits, and non-starchy vegetables was associated with less weight gain [ 14 ]. In the United States Nurses’ Health Study and Health Professionals Follow-up Cohort Study, both plant-based low-carbohydrate diets and healthy low-carbohydrate diets were found to reduce body weight, and the association was stronger in young, obese, and less active populations [ 49 ]. Several mechanisms support the reduction in the risk of obesity through high-quality carbohydrates: low GI and high dietary fiber promoting satiety, reducing appetite and fat storage, increasing fat oxidation, and changing the microbiome to reduce food intake [ 50 , 51 , 52 ].…”