Blood And Breath Ketones Demonstrate Acute Insensitivity To Daily Nutritional Variation In Keto-adapted Female Bodybuilder

Document Type

Conference Presentation

Department

Health, Exercise, and Sport Sciences Department

Conference Title

American College of Sports Medicine - Medicine & Science in Sports & Exercise conference

Organization

American College of Sports Medicine

Location

San Diego, CA

Date of Presentation

9-1-2022

Journal Publication

Medicine & Science in Sports & Exercise

ISSN

0195-9131

DOI

10.1249/01.mss.0000880176.44230.7c

Volume

54

Issue

9S

First Page

407

Abstract

Ketogenic contest preparation has become more prevalent in the bodybuilding community. However, few studies have explored the effect of minor nutrient fluctuations on daily blood and breath ketone values during prolonged in-season dieting. PURPOSE: To evaluate acute relationships between diet and ketone levels in a competitive bodybuilder. METHODS: We tracked an IFBB professional female bodybuilder for 75 consecutive days of ketogenic contest preparation. Independent variables were daily kcals consumed, proportions of fat, protein, and carbohydrate, amounts of sodium and potassium, total fluid volume, and coffee intake. We also estimated daily caloric expenditure using a FitBit Charge 3 activity tracker. Dependent variables were blood ketones measured with a Keto-Mojo device and breath ketones measured with a Ketonix Professional Breath Ketone Analyzer. We collected a fasted test each morning and repeated testing at night. Linear regressions evaluated relationships between independent and dependent variables. The prior day’s behaviors served as predictors for fasted ketones; the same day’s behaviors were used to predict nighttime values. RESULTS: Daily nutritional intake was 1604.8 ± 498.6 kcal, composed of 123.9 ± 42.4 g fat, 92.9 ± 24.7 g protein, and 28.8 ± 13.9 g net carbohydrate. Fluid intake was 221.3 ± 47.3 oz, sodium was 8.1 ± 1.9 g, potassium was 6.8 ± 1.1 g, energy expenditure was 1841.0 ± 228.6 kcal, fasted blood ketones were 1.0 ± 0.3 mM, and breath values were 148.8 ± 62.6 ppm. Holding energy expenditure constant, linear regression found no effect of kcal, carbohydrate, protein, coffee, or potassium consumption on fasted ketone levels (p > 0.150). Modest associations emerged with fat, fluid, and sodium. Holding energy expenditure constant, increased fat intake predicted elevated blood ketones (p = 0.048; 95% CI of β = 0.000 to 0.005) but not breath values (p = 0.231). Lower breath ketones were predicted with more fluid (p = 0.016; 95% CI of β = -0.845 to -0.088) and sodium (p = 0.042; 95% CI of β = -0.017 to -0.000). Neither fluid (p = 0.893) nor sodium (p = 0.195) predicted blood values. No associations were found between any predictor and nighttime ketones (p > 0.250). CONCLUSIONS: Ketone levels remained relatively stable in the presence of acute fluctuations in nutrition and hydration in a dieting bodybuilder.

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