Low-Carbohydrate Diet Macronutrient Quality and Weight Change

Higher fiber higher carbohydrate diets better than lower carbohydrate lower fiber diets for diabetes management: Rapid review with meta-analyses

BACKGROUND

Some dietary recommendations continue to recommend carbohydrate restriction as a cornerstone of dietary advice for people with diabetes.

PURPOSE

We compared the cardiometabolic effects of diets higher in both fiber and carbohydrate with lower carbohydrate lower fiber diets in type 1 or type 2 diabetes.

DATA SOURCES

MEDLINE, Embase, and the Cochrane Database of Systematic Reviews up to June 24, 2024, with additional hand searching.

STUDY SELECTION

Randomized controlled trials in which both dietary fiber and carbohydrate amount had been modified were identified from source evidence syntheses on carbohydrate amount in people with diabetes.

DATA EXTRACTION

Two reviewers independently.

DATA SYNTHESIS

Ten eligible trials including 499 participants with diabetes (98% with T2) were identified from the potentially eligible 828 trials included in existing evidence syntheses. Pooled findings indicate that higher fiber higher carbohydrate diets reduced HbA1c (mean difference [MD] -0.50% [95% confidence interval -0.99 to -0.02]), fasting insulin (MD -0.99 μIU/mL [-1.83 to -0.15]), total cholesterol (MD -0.16 mmol/L [-0.27 to -0.05]) and low-density lipoprotein cholesterol (MD -0.16 mmol/L (-0.31 to -0.01) when compared with lower carbohydrate lower fiber diets. Trials with larger differences in fiber and carbohydrate intakes between interventions reported greater reductions. Certainty of evidence for these outcomes was moderate or high, with most outcomes downgraded due to heterogeneity unexplained by any single variable.

LIMITATIONS

Our predefined scope excluded trials with co-interventions such as energy restriction, which may have provided addition information.

CONCLUSIONS

Findings indicate the greater importance of promoting dietary fiber intakes, and the relative unimportance of carbohydrate amount in recommendations for people with diabetes.

Factors Associated with the Practice of Low-Carb and Low-Fat Diets among Participants of the Longitudinal Study of Adult Health (ELSA-Brasil)

In the field of nutrition, both low-carbohydrate (LCD) and low-fat (LFD) diets were initially intended for specific subgroups but are now being embraced by the broader population for various purposes, including aesthetics and overall health. This study aims to assess sociodemographic, health, and lifestyle factors influencing diet choices among public servants in the ELSA-Brasil cohort. Diets were classified as LCD or LFD based on the Brazilian Diabetes Society (<45%) and WHO guidelines (<30%) respectively. A total of 11,294 participants were evaluated (45.3% men; 54.7% women) with a mean age of 52 ± 0.08 years. Having overweight, altered waist circumference, and a history of smoking confers higher chances of adopting an LCD compared to the usual diet, while being over 52 years, non-White race/skin color, in a lower income stratum, and having diagnosis of hypertension and/or diagnosis of diabetes mellitus decrease these chances. Regarding LFDs, belonging to the non-White race/skin color, being over 52 years old, being divorced, and practicing low physical activity decrease the chances of following such a diet compared to the usual diet. In conclusion, factors like age, socioeconomic status, health, and physical activity levels can be the key to understanding why individuals choose restrictive diets beyond clinical advice.

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

To investigate the prospective relationship between macronutrient intake and overweight/obesity, data were collected in the China Health and Nutrition Survey (CHNS) from 1991 to 2018. Adults who participated in at least two waves of the survey and were not obese at baseline were selected as the study subjects. A total of 14,531 subjects were finally included with complete data. Overweight/obesity was defined as a body mass index (BMI) ≥ 24.0 kg/m2. The generalized estimating equation (GEE) was used to analyze the relationship between the percentage of energy intake from macronutrients and BMI and overweight/obesity. The percentages of energy intake from protein and fat showed an increasing trend (p < 0.01), and the percentage of energy intake from carbohydrate showed a decreasing trend (p < 0.01) among Chinese adults between 1991 and 2018. Adjusting for covariates, the energy intake from fat was positively correlated with BMI, while the energy intake from carbohydrates was negatively correlated with BMI. The percentage of energy intake from non-high-quality protein and polyunsaturated fatty acids (PUFA) were positively correlated with overweight/obesity. In contrast, monounsaturated fatty acids (MUFA) and high-quality carbohydrates were negatively correlated with overweight/obesity. In short, fat, non-high-quality protein, saturated fatty acids (SFA), and PUFA were positively correlated with the risk of obesity, whereas higher carbohydrate, MUFA, and high-quality carbohydrate intake were associated with a lower risk of obesity. Obesity can be effectively prevented by appropriately adjusting the proportion of intake from the three major macronutrients.