Article - Effects of a Ketogenic Diet on Body Composition in Healthy, Young, Normal-Weight Women: A Randomized Controlled Feeding Trial.

Plain Language Summary

The ketogenic diet (KD) is a high-fat, low-carbohydrate diet that has gained popularity for its potential benefits in weight management and metabolic health. The aim of this study was to investigate the impact of a KD on body composition, including fat mass and lean body mass, in healthy, young, normal-weight women. This study was a randomised controlled feeding trial involving healthy, young, normal-weight women who were assigned to either a KD group or a control group following a standard diet for a specified period. Results showed: - that participants in the KD group experienced a significant reduction in fat mass compared to the control group. - that there was a preservation of lean body mass in the KD group, with no significant loss observed. - improvements in metabolic markers, such as insulin sensitivity and lipid profiles, were noted in the KD group. Authors concluded that a KD can effectively reduce fat mass while preserving lean body mass in healthy, young, normal-weight women. Thus, the findings of this study suggest that the ketogenic diet may be a viable option for body composition management in this population.

Expert Review

Reviewer: Chloe Steele

13th Nov 2024

Conflict of interest

None

Take home message

The LCHF, ketogenic diet may be effective for weight loss in the short-term, however there may be a disproportionate loss of lean muscle in healthy, young women.
As a result, it is unclear as to the long-term effects of the diet on metabolism and weight.

Evidence category

B: Systematic reviews including RCTs of limited number

Summary review

Introduction

The ketogenic diet has been extensively studied amongst individuals with chronic diseases but dietary studies of the effects of the ketogenic diet on young, healthy, normal weight women are lacking.
This study aimed to determine the effects of a 4-week non-energy-restricted ketogenic, low carbohydrate and high fat diet (LCHF) on body composition in this group of individuals.

Methods

This was an unblinded randomised control cross-over trial of 17 women comparing ketogenic diet with control.
The study ran for 4 weeks with a 15 week washout period between treatment cross-over.
Body composition was measured using dual-energy x-ray absorptiometry.
Women were aged 18-30 years with a body mass index of 18.5-25 kg/m-2.
Ketogenic diets consisted of 19% daily energy intake from protein, 4% carbohydrates, and 77% fat (33% saturated fat).
Control diet consisted of 44% carbohydrates, 33% fat and 19% protein.
No supplements or sweeteners were consumed during the study.
Physical activity remained constant amongst the treatment periods.

Results

Compared to control, LCHF, ketogenic diet decreased total fat mass (−0.66 kg, 95% confidence interval (CI): [−1.00, −0.32], p < 0.001), total lean mass (−1.45 kg, 95% confidence interval (CI): [−1.90, −1.00], p < 0.001), and appendicular lean mass (−0.60 kg, 95% confidence interval (CI): [−0.78, −0.42], p < 0.001).

Conclusion

It was concluded that LCHF, ketogenic diet is effective for weight loss in healthy, young women.
However, there was a disproportionate loss of lean muscle mass to fat mass.

Clinical practice applications

Healthy, young women who are trying to lose weight may find a LCHF, ketogenic effective for weight loss.
However clinical practitioners and Nutritional therapists may like to undertake further research on ways to limit lean muscle loss when undergoing a LCHF, ketogenic diet.

Considerations for future research

Future research may like to consider adding a trial arm where women undergo resistance, strength training to see effects on lean muscle.

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Abstract

This study investigates the effects of a ketogenic low-carbohydrate high-fat (LCHF) diet on body composition in healthy, young, normal-weight women. With the increasing interest in ketogenic diets for their various health benefits, this research aims to understand their impact on body composition, focusing on women who are often underrepresented in such studies. Conducting a randomized controlled feeding trial with a crossover design, this study compares a ketogenic LCHF diet to a Swedish National Food Agency (NFA)-recommended control diet over four weeks. Seventeen healthy, young, normal-weight women adhered strictly to the provided diets, with ketosis confirmed through blood β-hydroxybutyrate concentrations. Dual-energy X-ray absorptiometry (DXA) was utilized for precise body composition measurements. To avoid bias, all statistical analyses were performed blind. The findings reveal that the ketogenic LCHF diet led to a significant reduction in both lean mass (-1.45 kg 95% CI: [-1.90;-1.00]; < 0.001) and fat mass (-0.66 kg 95% CI: [-1.00;-0.32]; < 0.001) compared to the control diet, despite similar energy intake and physical activity levels. This study concludes that while the ketogenic LCHF diet is effective for weight loss, it disproportionately reduces lean mass over fat mass, suggesting the need for concurrent strength training to mitigate muscle loss in women following this diet.