For Weight Loss With a Low-Carb Diet, Quality Matters

TOPLINE:

A high-quality, low-carbohydrate diet (LCD), rich in plant-based proteins and healthy fats, was associated with slower weight gain, while a lower-quality LCD was associated with the reverse.

METHODOLOGY:

• Prospective cohort study included 123,332 participants from the Nurses’ Health Studies (NHS, 1986-2010 and 1991-2015) and the Health Professionals Follow-up Study (HPFS, 1986-2018).
• Diets assessed by questionnaires were categorized as: (1) total LCD (TLCD), emphasizing overall lower carbohydrate intake; (2) animal-based LCD (ALCD), emphasizing animal-sourced protein and fat; (3) vegetable-based LCD (VLCD), emphasizing plant-sourced protein and fat; (4) a healthy LCD (HLCD), emphasizing less refined carbohydrates, more plant protein, and healthy fat; and (5) unhealthy LCD (ULCD), emphasizing less healthful carbohydrates, more animal protein, and unhealthy fat.
• The primary outcome was 4-year reported changes in body weight, divided into quintiles, with Q3 = no change, Q1 = largest decrease, and Q5 = largest increase.

TAKEAWAY:

• Participants gained a mean of 1.3 kg over each 4-year interval, with gains of 0.8, 1.8, and 0.5 kg for NHS, NHSII, and HPFS, respectively.
• After adjustment for baseline and concomitant changes in lifestyle and demographic factors, compared with participants with no change in the TLCD score over 4-year intervals, those with the largest increase (Q5) in the TLCD score did not have significant weight change (0.03 kg), while those with the largest decrease (Q1) in the TLCD score had significantly less weight gain (−0.20 kg).
• Similarly, those following a VLCD with Q5 change, compared with those with stable Q3 adherence, experienced 0.21 kg less weight gain, and those with Q1 change experienced 0.17 kg less weight gain, both significant.
• Adhering to an ALCD was associated with more weight gain over time, with each 1 standard deviation (SD) increase in ALCD associated with a significant 0.13 kg more weight gain over 4-year intervals.
• Opposite results were seen for ULCD and HLCD scores, where a 1-SD increase in HLCD and ULCD was associated with a significant 0.36 kg weight loss and 0.39 kg weight gain, respectively, over 4-year intervals.
• The associations were stronger among individuals with baseline body mass index ≥ 30 kg/m².

IN PRACTICE:

“The findings of this cohort study underscore the importance of diet quality within LCD patterns for weight management… Overall, the study findings argue against the sole focus of macronutrient quantity for weight management and suggest the crucial role of nutrient quality in maintaining a healthy body weight.”

SOURCE:

This study was conducted by Binkai Liu, MS, of the department of nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, and colleagues.

The findings were published online in JAMA Network Open .

LIMITATIONS:

• Self-reported data.
• Observational study, potential for residual confounding.
• No body composition measurement.
• Study population was mainly White health professionals.

DISCLOSURES:

This study was funded by research grants from the National Institutes of Health, and one coauthor is supported by a postdoctoral fellowship award from the Canadian Institutes of Health Research.

A version of this article appeared on Medscape.com.