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Session: Energy and Macronutrient Metabolism (Oral 24)

(OR24-01-23) Diet Order Affects Energy Intake and Weight Change During a Crossover Low-carbohydrate vs. Low-fat Diet Study

Tuesday, July 25, 2023
8:00 AM – 8:12 AM ET
Location:  Commonwealth
PRAC ELPC

    Presenting Author(s)

  • Christina M. Sciarrillo, PhD, RD

    Postdoctoral Fellow
    National Institute of Diabetes and Digestive and Kidney Disease
    Rockville, Maryland, United States

    Disclosure(s): No relevant financial relationship(s) with ineligible companies to disclose.

    • Co-Author(s)

  • JG

    Juen Guo, PhD

    NIH/NIDDK
    Bethesda, Maryland, United States

  • Aaron Hengist, PhD

    Postdoctoral Visiting Fellow
    NIDDK
    Bethesda, Maryland, United States

  • VD

    Valerie L. Darcey

    National Institutes of Health

  • Kevin D. Hall, PhD

    Senior Investigator
    NIDDK, NIH
    Bethesda, Maryland, United States

Disclosure(s):
Christina M. Sciarrillo, PhD, RD: No relevant financial relationship(s) with ineligible companies to disclose.
Objectives: We examined the effect of diet order on ab libitum energy intake and body weight change during a 4-week random order crossover study of a low carbohydrate (LC) versus a low fat (LF) diet.

Methods: Twenty adults aged 29.9 ± 1.4y (mean ± SEM) with BMI of 27.8 ± 1.3 kg/m2 were admitted to the National Institutes of Health Clinical Center as in-patients where they were randomized to consume a plant-based, LF diet (10% fat) or an animal-based, ketogenic, LC diet (10% carbohydrate) for 2 weeks after which they were immediately provided the alternate diet for another 2 weeks. All study meals were provided for the duration of the study. Ad libitum energy intake and body weight were measured daily. Body composition and substrate oxidation were measured each week.

Results: Whereas diet order did not impact within subject differences in ad libitum energy intake between the LC and LF diets (143 ± 140 kcal/d; p = 0.32), there was a significant diet order effect over the 4-week study period, such that subjects randomized to consume the LC diet followed by the LF diet (LC first) consumed 754 ± 247 kcal/d less than subjects randomized to receive the LF diet followed by the LC diet (LF first) (p = 0.0024) after adjusting for baseline resting energy expenditure. Over the entire 4-week study period, consuming the LC diet first produced both greater total weight loss (LC first: 4.2 ± 0.9 kg, LF first: 1.5 ± 0.9 kg; p < 0.001) and greater total fat loss (LC first: 1.6 ± 0.4 kg body fat, LF first: 0.1 ± 0.4 kg body fat; p = 0.015) compared to consuming the LF diet first. The only significant difference noted between participants randomized to the LC first group compared to the LF first group was a lower baseline respiratory quotient in the overnight fasted state (0.80 ± 0.02 vs. 0.86 ± 0.01; p = 0.02).

Conclusions: These data suggest that diet order influences daily ad libitum energy intake and the rates of body weight and fat change within the context of an in-patient crossover study of LC vs. LF diets. Whether such a diet order effect persists over longer periods or in other settings is unknown.

Funding Sources: Intramural Research Program of the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health