Physiologic Adaptation to Macronutrient Change Distorts Findings from Short Dietary Trials : Reanalysis of a Metabolic Ward Study

Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved..

An influential 2-wk cross-over feeding trial without a washout period purported to show advantages of a low-fat diet (LFD) compared with a low-carbohydrate diet (LCD) for weight control. In contrast to several other macronutrient trials, the diet order effect was originally reported as not significant. In light of a new analysis by the original investigative group identifying an order effect, we aimed to examine, in a reanalysis of publicly available data (16 of 20 original participants; 7 female; mean BMI, 27.8 kg/m2), the validity of the original results and the claims that trial data oppose the carbohydrate-insulin model of obesity (CIM). We found that energy intake on the LCD was much lower when this diet was consumed first compared with second (a difference of -1164 kcal/d, P = 3.6 × 10-13); the opposite pattern was observed for the LFD (924 kcal/d, P = 2.0 × 10-16). This carry-over effect was significant (P interaction = 0.0004) whereas the net dietary effect was not (P = 0.4). Likewise, the between-arm difference (LCD - LFD) was -320 kcal/d in the first period and +1771 kcal/d in the second. Body fat decreased with consumption of the LCD first and increased with consumption of this diet second (-0.69 ± 0.33 compared with 0.57 ± 0.32 kg, P = 0.007). LCD-first participants had higher β-hydroxybutyrate levels while consuming the LCD and lower respiratory quotients while consuming LFD when compared with LFD-first participants on their respective diets. Change in insulin secretion as assessed by C-peptide in the first diet period predicted higher energy intake and less fat loss in the second period. These findings, which tend to support rather than oppose the CIM, suggest that differential (unequal) carry-over effects and short duration, with no washout period, preclude causal inferences regarding chronic macronutrient effects from this trial.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:154

Enthalten in:

The Journal of nutrition - 154(2024), 4 vom: 04. Apr., Seite 1080-1086

Sprache:

Englisch

Beteiligte Personen:

Soto-Mota, Adrian [VerfasserIn]
Jansen, Lisa T [VerfasserIn]
Norwitz, Nicholas G [VerfasserIn]
Pereira, Mark A [VerfasserIn]
Ebbeling, Cara B [VerfasserIn]
Ludwig, David S [VerfasserIn]

Links:

Volltext

Themen:

Body composition
Clinical trial
Dietary Carbohydrates
Insulin
Journal Article
Low-carbohydrate diet
Low-fat diet
Macronutrients
Methodology
Obesity

Anmerkungen:

Date Completed 15.04.2024

Date Revised 15.04.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.tjnut.2023.12.017

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM366195379