The Data Behind Popular Diets for Weight Loss

Micronutrient Inadequacy Differs by Intake of Fat Amount and Class Among Adults That Consume a Restricted Carbohydrate Diet: National Health and Nutrition Examination Survey, 2007-2018

BACKGROUND

Restricted carbohydrate diets remain among the most popular for weight loss and general health improvement. Recent evidence demonstrates that carbohydrate restricted diets are low in overall diet quality, yet their association with micronutrient inadequacy has not been well characterized at a population-level in adults in the United States.

OBJECTIVE

To evaluate the prevalence of not meeting daily micronutrient recommendations in US adults that met the Acceptable Macronutrient Distribution Ranges and those who restricted carbohydrate intake to <45% energy, and to examine the effect of total fat and fat class on these results for the restricted carbohydrate group.

DESIGN

This study utilized 24-hour recall data on food and nutrient intake from respondents in the National Health and Nutrition Examination Survey 2007-2018.

PARTICIPANTS/SETTING

This study included 15 029 respondents who were aged 20 years and older, had complete and reliable nutrient intake data, and were not pregnant or breastfeeding.

MAIN OUTCOME MEASURES

The main outcome was the prevalence of not meeting daily micronutrient recommendations based on Dietary Reference Intakes.

STATISTICAL ANALYSES PERFORMED

The National Cancer Institute's usual intake methodology was used to estimate usual dietary intake and the prevalence of the US adult population not meeting the Dietary Reference Intakes.

RESULTS

Compared with participants that met the Acceptable Macronutrient Distribution Ranges, those that consumed restricted carbohydrate diets had greater prevalence of inadequacy (%

CONCLUSION

This study shows that there are different types of restricted carbohydrate diets that can be characterized by fat amount and class, each with their own association with micronutrient intake. This information can be used by clinicians to provide more targeted dietary counseling to their patients who restrict carbohydrates, depending on the amount and type of fat they consume.

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Key Words

• Carbohydrate restriction
• Fat composition
• Micronutrient inadequacy
• NHANES
• Popular diet

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MESH Headings

• Humans
• Nutrition Surveys
• Female
• Adult
• Micronutrients/deficiency
• Micronutrients/administration & dosage
• Micronutrients/analysis
• Male
• United States/epidemiology
• Middle Aged
• Dietary Fats/administration & dosage
• Dietary Fats/analysis
• Dietary Fats/classification
• Diet, Carbohydrate-Restricted/statistics & numerical data
• Diet, Carbohydrate-Restricted/adverse effects
• Young Adult
• Aged
• Recommended Dietary Allowances
• Energy Intake
• Prevalence

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Affiliation(s)

Alaa Ilayan Department of Human Sciences, The Ohio State University, Columbus, Ohio. Current Affiliation: Post-Master's Fellow, Oak Ridge Institute for Science and Engineering, 1299 Bethel Valley Rd, Oak Ridge, TN 37830
Dakota Dustin The Ohio State University Nutrition PhD Program, Graduate School, The Ohio State University, Columbus, Ohio
Corina Kowalski College of Arts & Sciences, William & Mary, Williamsburg, Virginia
Martha A Belury Department of Food Science and Technology, The Ohio State University, Columbus, Ohio
LuAnn K Johnson Independent Contractor, Warren, Minnesota
Zach Conrad Department of Kinesiology, William & Mary, Williamsburg, Virginia; Global Research Institute, William & Mary, Williamsburg, Virginia.

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Nutritional status in the era of highly effective CFTR modulators

Advances in cystic fibrosis (CF) diagnostics and therapeutics have led to improved health and longevity, including increased body weight and decreased malnutrition in people with CF. Highly effective CFTR modulator therapies (HEMT) are associated with increased weight through a variety of mechanisms, accelerating trends of overweight and obesity in the CF population. Higher body mass index (BMI) is associated with improved pulmonary function in CF, yet the incremental improvement at overweight and obese BMIs is not clear. Improvements in pulmonary health with increasing BMI are largely driven by increases in fat-free mass (FFM), and impact of HEMT on FFM is uncertain. While trends toward higher weight and BMI are generally seen as favorable in CF, the increased prevalence of overweight and obesity has raised concern for potential risk of traditional age- and obesity-related comorbidities. Such comorbidities, including impaired glucose tolerance, hypertension, cardiac disease, hyperlipidemia, fatty liver, colon cancer, and obstructive sleep apnea, may occur on top of pre-existing CF-related comorbidities. CF nutrition recommendations are evolving in the post-modulator era to more individualized approaches, in contrast to prior blanket high-fat, high-calorie prescriptions for all. Ultimately, it will be essential to redefine goals for optimal weight and nutritional status to allow for holistic health and aging in people with CF.

Should carbohydrate-modified diets be the first option for weight loss in people with impaired glucose metabolism? A scoping review

While the "precision nutrition" movement is at an early stage of development, several investigations have compared low-fat versus carbohydrate (CHO)-modified diets (i.e., low-or-reduced-CHO, low glycemic index/load diets, and high-fiber) in people with normal versus impaired glucose metabolism. The purpose of this scoping review was to summarize evidence in support of the hypothesis that CHO-modified diets are more effective for weight loss among people with impaired glucose metabolism. Fifteen articles were included in this review: seven retrospective analyses of randomized clinical trials and eight prospective randomized clinical trials with prespecified hypotheses related to a diet (low-fat vs. CHO-modified) × phenotype (normal vs. impaired) interaction. Evidence in support of the hypothesis was identified in six of seven retrospective and three of eight prospective studies, which led to a recommendation of CHO-modified diets as a first-line option for people with impaired glucose metabolism. However, the evidence in support of this recommendation is relatively weak, and dietary prescriptions should consider additional contextual information that may influence overall dietary adherence. Additional and rigorous research using innovative randomized experimental approaches is needed for stronger dietary weight loss recommendations based on pretreatment glycemic status.